Advances in Marine Biology, Volume 10

Advances in

MARINE BIOLOGY VOLUME 10

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Advances in

MARINE BIOLOGY VOLUME 10 Edited by

SIR FREDERICK S. RUSSELL Plymouth, England

and

SIR MAURICE YONGE Edinburgh, Scotland

Academic Press London and New York

1972

ACADEMIC PRESS INC. (LONDON) LTD.

24-28 OVAL ROAD LONDON NW1

U S . Edition published by ACADEMIC PRESS INC.

1 11

FIFTH AVENUE

NEW YORK, NEW YORK

10003

Copyright 0 1972 by Academic Press Inc. (London) Ltd.

All rights reserved

NO PART OF THIS BOOK MAY B E REPRODUCED IN ANY FORM B Y PHOTOSTAT, MICROFILM, OR ANY, OTHER MEANS, WITHOU!I?'WRIl'TENPEEGRIISSION FROM THE PUBLISHERS

I S B N : 012-026110-3 Library of Congress Catalog Card Number: 63-14040

PRINTED I N GREAT BRITAIN B Y THE WHITEFRIARS PRESS LTD. LONDON AND TONBRIDQE

CONTRIBUTORS TO VOLUME 10 J. I. CAMPBELL, Department of Zoology, University of Glasgow, Scotland.

C. B. COWEY, Institute of Marine Biochemistry, St. Fittick’s Road, Aberdeen, Scotland. R. K. DELL,Dominion Museum, Wellington, New Zealand. P. S . MEADOWS, Department of Zoology, University of Glasgow, Xcotland. HILARYB. MOORE,University of Miami, School of Marine and Atmospheric Sciences, Miami, Floridu, U.S.A.

J. R. SARGENT, Institute of Marine Biochemistry, St. Fittick’s Road, Aberdeen, Scotland.

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CONTENTS CONTRIBUTORSTO VOLUME 10

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Antarctic Benthos

R . K . DELL

I . Introduction

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I1. The Antarctic Environment . .. A . The Antarctic Biological Region . . B . Terminology. . .. .. .. C. Subdivisions of the Antarctic Region D . Endemism . . .. . . ..

I11. History of Benthic Investigations

IV. The Fauna of Antarctica .. A . Foraminifera B . Porifera .. C. Coelenterata D . Turbellaria . . E . Nematode . . F. Nemertea . . G. Echinoderida H . Polychaeta . . I. Priapulida, . . J. Sipuncula . . K . Echiura .. L . Brachiopoda .. M. Bryozoa .. N Pycnogonida

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0. Crustacea . . P. Mollusca .. Q . Echinodermata R. Ascidiacea .. S. Fishes ..

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VII. Brooding or Viviparity in Antarctic Animals A. Echinodermata .. .. .. B. Mollusca . . .. .. .. C. Ascidiacea . . .. .. .. D. Polychaeta . . .. .. .. E. Nemertea . . .. .. .. F. Reasons for Incidence of Viviparity VIII. Bipolarity

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IX. Origins of the Antarctic Biota X. Conclusions

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XI. Bibliography and References

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Aspects of Stress in the Tropical Marine Environment

HILARY B. MOORE I. Introduction

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111. Physical Aspects . . A. Temperature B. Salinity .. C. Radiation . . D. Tides ..

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IV. Biological Aspects .. .. A. Temperature Tolerance . . B. Intertidal Zonation *. C. Critical Levels .. .. D. Growth Rates and Temperature E. Seasonal Growth Patterns. . F. Growth After Sexual Maturity G. Longevity . . .. *. H. Extremes of Size . . .. I. Variability . . .. J. Breeding .. .. .. K. Phases of Water . .. .

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VII. Acknowledgments. .

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V. Discussion VI. Summary

VIII. References and Bibliography

Habitat Selection by Aquatic Invertebrates

P. S. MEADOWSAND J. I. CAMPBELL

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11. The Physical and Chemical Environment A. Intertidal Animals . . .. ..

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B. Marine Animals .. C. Freshwater Animals D. Interstitial Animals

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111. Commensal and Parasitic Associations . . IV. The Biological Environment A. Settlement Behaviour B. Gregariousness ..

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C. Spacing Out and Aggression D. Associations with Plants . .

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E. Larval Chemoreception at Settlement F. Habitat Selection and Micro-organisms G. Food Selection .. H.Homing .. I. Oviposition Preferences

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V. Physiology and Viability

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VIII. Individual Variation, the Colonization of New Habitats, and the Origin of New Species .. .. .. 346 IX. Conclusion

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XI, Acknowledgments.. XII.

References

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Fish Nutrition C. B. COWEYAND J. R. SARGENT

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11. Proteins . .. .. .. A. Nitrogen Balance . . .. .. B. The Calorific Value of Protein . . .. .. C. Essential Amino Acid Requirements . . .. D. Dietary Protein Requirement . . .. .. E. Quantitative Amino Acid Requirements .. F. The Use of Nitrogen Supplements .. .. G. The Biological Value of Food Protein . . .. H. The Assimilation of Ingested Protein . . .. I. Food Energy and Protein Requirement . .. J. Growth Promoting Effects of Anabolic Steroids and other Compounds . . .. .. ..

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111. Carbohydrates . . .. .. A. Utilization * . .. B. Energy Yielding Pathways

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IV. Lipids . . .. .. .. A. Lipid Types and their Functions B. Fatty Acids . . .. .. C. Cholesterol . . .. ..

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VII. Peeding Rate and Conversion Rate

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V. Vitamins . . .. .. A. Fat Soluble Vitamins B. Water Soluble Vitamins C. Vitamin Requirements VI. Body Composition

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CUMULATIVEINDEX OF AUTHORS

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CUMULATIVE INDEX OF TITLES . .

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VIII. Least-Cost Formulation IX. Perspectives

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.. AUTHOR INDEX . .

X. References

TAXONOMIC INDEX SUBJECT INDEX ..

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Adv. mar. Bwl., Vol. 10, 1972, pp. 1-216

ANTARCTIC BENTHOS R. K. DELL Dominion Museum, Wellington, New Zealand I.

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Introduction The Antarctic Environment . . .. A. The Antarctic Biological Region B. Terminology . .. .. .. C. Subdivisions of the Antarctic Region .. D. Endemism . . .. .. .. .. .. 111. History of Benthic Investigations .. .. . IV. The Fauna of Antarctica .. .. A. Foraminifera .. .. B. Porifera . C. Coelenterata . . .. .. *. D. Turbellaria, E. Nematoda .. .. .. .. .. F. Nemertea . . .. . . .. .. .. .. C . Echinoderida .. H. Polyohaeta. .. .. .. I. Priapulida J. Sipuncula . . .. .. .. .. .. K. Echiura L. Brachiopoda . .. .. .. M. Bryozoa . .. .. N. Pycnogonida .. .. 0. Crustacea .. P. Mollwca .. .. . . .. .. Q. Echinodermata R. Ascidiacea . . .. .. .. S. Fishes . . .. .. .. .. ,. V. Marine Algae .. A. Algal Ecology and Zonation * . .. B. Origin of Antarctic Algae VI. Benthic Assemblages .. .. .. .. .. A. Bottom Photigraphs VII. Brooding or Viviparity in Antarctic Animals .. .. A. Echinodermata B. Mollusca .. . . .. .. C. Ascidiacea . .. .. .. D. Polychaeta.. .. E. Nemertea .. .. .. F. Reasons for Incidence of Viviparity VIII. Bipolarity . . .. IX. Origins of the Antarctic Biota X. Conclusions XI, Bibliography and References

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R. K. DELL

I. INTRODUCTION The writer has twice previously prepared short reviews of Antarctic marine biology. The first (Dell, 1952) was written during what can now be recognized as an interregnum between two major periods of biological endeavour in the Antarctic. The main line of British oceanographic interest had already turned to other fields and active biological investigation by the Discovery Investigations had in fact ceased. The great international assault on the Antarctic stimulated by the International Geophysical Year (IGY) was about to commence. The second review (Dell, 1965) was written when it was still too soon to assess what biological results had in fact been achieved. For various reasons, there is often a significant time lag between biological field work and the publication of results. I n 1964 many of the biological results that had been achieved had not been published and even some that had been published had not reached the Southern Hemisphere. I n the last few years publication has begun to catch up, and a wealth of material is becoming available. The year 1965 did not seem to be a very propitious period in which to assess progress. The present period may be little better, but at least it is now obvious that no time in the immediate future will provide the kind of hiatus during which reviews seem best attempted. Major papers on Antarctic marine biology will be appearing regularly over the next decade. The writer has kept files on Antarctic biology for many years. A major review of literature in preparation for this contribution was carried out throughout 1970 and the major part was written during the first half of 1971. It has not proved possible to set an absolute deadline beyond which reference to material could not be included. All literature which has been received in New Zealand up to the beginning of May 1971 has been included. Because of postal inconsistencies there will undoubtedly be anomalies in the treatment of literature produced during the last six months. The aim has been to give some account of the work carried out to date on Antarctic benthic plants and animals. The area included in the Antarctic has been very definitely circumscribed to cover the Antarctic region defined herein as the shores of the Antarctic Continent, the South Shetlands, South Orkneys, the South Sandwich Islands and South Georgia together with Bouvet Island. The Subantarctic has been excluded, and such islands as Kerguelen, Heard and Macquarie have been considered basically Subantarctic. Consideration of Subantarctic biology raises many other problems since the biota cannot be so readily circumscribed, and involves much closer relationships with associated

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regions such as South America, New Zealand and Australia. It surely warrants treatment as a unit on its own. At the same time the approach to the Antarctic Region has been essentially faunal and the extensions of the Antarctic fauna have been traced whenever necessary. Some authors have not made a clear distinction between Antarctic and Subantarctic, and in reviewing their results the geographical scope may have been extended. Parasitic forms have not been treated in detail unless the occurrences are of biogeographical interest.

11. THE ANTARCTIC ENVIRONMENT I n complete contrast to Arctic conditions, Antarctica consists of a large land mass invested with ice sheets of varying thickness, and surrounded by a great body of water, the Southern Ocean (Herdman et d , 1966). Extending southwards into the Southern Ocean towards Antarctica are three spearheads of land, each a potential pathway whereby organisms living on the shelves associated with three major landmasses could disperse, or have dispersed, southwards. From South America, the Scotia Arc with its surface features of the Falklands, South Georgia, the South Sandwich and South Orkney Islands and the South Shetlands, curves towards the most northerly extension of the Antarctic Continent, the Antarctic Peninsula. New Zealand and Australia provide a more fragmented pathway from Asia through the Indo-Malayan Archipelago. South Africa stops at a greater distance from the Antarctic Continent but provides shallow water contacts northwards into the Indian Ocean on one coast and into the Atlantic on the other. Deeper water organisms are brought closer into contact with Antarctic waters, the Southern Ocean being but a continuation of the Pacific, Indian and Atlantic Oceans. There is no shortage of potential migration routes through which biogeographers can derive the Antarctio biota, or through which it may be considered to disperse. The biogeographer must try to deduce the routes that have actually been used by the plants and animals concerned. There have been many recent general accounts of the physical oceanography of Antarctic and Subantarctic waters, some with a biological slant, (Deacon, 1937, 1960; Mackintosh, 1946, 1960; Knox, 1960 ; Ostapoff, 1965 ; Brodie, 1965 ; El-Sayed, 1968). The biological significance of the water current patterns in the Antarctic has been discussed by El-Sayed (1968) based on Deacon (1937). The surface manifestations of Antarctic Surface Water near the continent surrounded by a belt of Subantarctic Surface Water separated

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by the Antarctic Convergence result from a pattern of subsurface water movement. Mainly because of the westerly wind, the surface waters of the Southern Ocean move in an easterly direction to form the Antarctic Circumpolar Current. Cold sea water originating along the edge of the Continent is cold and dense and sinks to move towards the north as Antarctic Bottom Water. Some of the Antarctic Surface Water has a northerly component which sinks to an intermediate level at the Antarctic Convergence to form Subantarctic Intermediate Water. Highly saline deep waters from the north, rich in nutrients, move southwards at intermediate levels to replace the northward moving waters mentioned above, to rise close to the surface near the Continent. This injection of nutrient salts in the Antarctic, together with the effect of sunlight for 24 h of the day in southern summer results in an extremely high period of summer productivity. In marked contrast to other areas the supply of nutrient salts from this source is so great that productivity is probably never limited from a lack of nutrients in the Antarctic. There is of course a marked contrast in productivity between summer and winter. The results as recorded by a human diver working throughout the year have been vividly expressed by Peckham (1964). During the winter the absence of phytoplankton meant that the sea water was exceptionally clear. A small lighted torch bulb was still visible to a depth of almost 100 m. The first sunlight in September allowed exceptionally clear observation but by mid-summer the heavy phytoplankton growth often cut visibility to less than 10 ft. The unique contribution of Antarctic waters in this respect can better be appreciated by the objective estimation (El-Sayed, 1968) that the waters south of the Antarctic Convergence (about 5% of the oceans of the world) support a total production equivalent to about 20% of that produced by all the oceans of the world. This abundance of phytoplankton provides an almost unlimited source of food, directly or indirectly, to the benthos. The fact that i t is seasonal imposes physiological rhythms which have as yet been investigated in only a relatively few organisms. The continental shelf around Antarctica is narrow everywhere except in the two embayments of the Ross and Weddell Seas (Brodie, 1965). As Brodie has noted the sudden change in slope which marks the outer limit of the shelf and the beginning of the continental slope is much deeper than the 150 m or so that is commonly found elsewhere. Around the Antarctic Continent the change in slope may occur at depths between 400 and 600 m, and in the Ross Sea it occurs at nearly 800 m. In most areas the continental slope descends without any very complicated bottom features to depths of about 3 000 m. Three areas of

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complex topography mentioned by Brodie occur off the Antarctic Peninsula, forming the southern limb of the Scotia Ridge, off the Balleney Islands-Scott Island area, and in 70°E,in the form of the Kerguelen Ridge. Outside the continental slope the sea floor extends as broad ridges or deep basins. Essentially three main basins are involved, an Atlantic-Indian-Antarctic Basin, an Eastern Indian-Antarctic Basin, and a Pacific-Antarctic Basin. All three basins are cut off to one extent or another to the north by major ridges arranged more or less in a circumpolar fashion, whose crests lie in depths of less than 3 000 m. Andriashev (1965) has described the peculiar nature of the Antarctic continental shelf, commenting on the " sunken " nature with an edge a t 400-500 m or more, and the presence within the shelf limits of " innershelf depressions " and narrow trenches which may reach depths of 1 000 m or more. The bottom sediments in Antarctic seas are influenced primarily by the fact that practically all the effective transport of terrigenous material is by ice, The effect of glacial deposits carried by ice will extend to the northern limit of pack ice, although the intensity of effect must diminish from the continental boundaries outwards. Glacial sediments do dominate almost to the limits of pack ice. This is not a uniform sediment, ranging as it does from fine muds to large boulders. There are areas such as those in which thick belts of sedentary organisms occur where sedimentation for one reason or another must be minimal, and others such as deposits of barnacle plates (Bullivant, 1967) where the fine sediments appear to be swept away by bottom currents. A t its northern boundary the glacial deposit gives way to a zone of diatom ooze, some 1 000-2 000 km wide. Diatoms occur plentifully enough to the south but the amount of terrigenous material available effectively masks the deposit. The northern limits of the zone of diatom ooze extends somewhat north of the Antarctic Convergence where diatom production is replaced by Foraminifera and Globigerina ooze takes over. Within the zone of Diatom ooze there can be extensive areas influenced by local volcanic action.

A . The Antarctic biological region For those who like order in all things, it is unfortunate that the Antarctic Continent cannot be confined within the Antarctic Circle instead of buIging inconsiderately beyond i t in several areas, and extending the Antarctic Peninsula well beyond it to about 63"s. Some of the benthic organisms of the Southern Ocean live in close association

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with this continent, some in the ocean basins around its periphery. It is probable that this latter group is better considered in relation to world abyssal faunas, rather than as part of a specific Antarctic fauna. Such evidence as is available points in this direction. The Antarctic Circle is a geographical abstraction, not a biological boundary, even for terrestrial organisms. The coastal area of the Antarctic Continent itself proves to be an equally unsatisfactory boundary for a specific Antarctic benthic biota. The islands of the South Shetlands are so closely associated with the Antarctic Peninsula geographically and faunally that these must be included. However, a large part of the plants and animals living within this area is not confined to it but extends to varying degrees, particularly through the islands of the Scotia Arc. The one physical boundary which has proved a particularly useful biological boundary especially for the organisms living in the surface waters of the Southern Ocean has been the Antarctic Convergence. The position of the Convergence fluctuates throughout the year, and from year to year, but this creates no major problems in delineating the distribution of planktonic organisms and for those animals dependent upon the plankton. The literature on the relationship of plankton to the waters on both sides of the Antarctic Convergence is considerable and has a vast literature of its own. A recent summary is that of Mackintosh (1960). Many of the attempts to delimit the Antarctic Region seem to be based upon the wrong criteria. I n a biogeographical discussion, the evidence for subdivision should be essentially faunal. The primary task should be to determine what the animals do, and where they occur, rather than how well they conform to some stated scheme, however logical this may be. Kusakin (1968, p. 355) criticizes rather scathingly “ the excessively pedantic utilization of the zonal-geographical method at the expense of the faunistic (or floristic) method ”. In considering the benthos, there seems no reason why the Antarctic Convergence should be a benthic boundary except in a very indirect way. I n group after group the Antarctic fauna, or appreciable elements of it, extends along the island groups of the Scotia Arc as far as South Georgia. But most of the evidence we have is for the narrow continental shelf and the continental slope and the shelves and slopes around the islands. Except in the region of the Scotia Arc, the Antarctic shelf fauna cannot extend as far north as the Antarctic Convergence. The distinction is well shown in Hedgpeth (1969a, p. 6, Fig. 10)where the area within the Antarctic Convergence (i.e. the “Antarctic Region ”) is far greater in extent than the ‘‘ Continental Subregion ”. The abyssal faunas of the

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various deep-water basins which intrude inside the boundary of the Antarctic Convergence will surely extend south of the Convergence. Cailleux (1961) in a discussion of endemism in the Antarctic, and after analysing a long series of systematic works concluded that a majority of authors included the South Shetlands, South Orkneys and South Sandwich Islands in the Antarctic, and that Bouvet Island was usualIy included. For the majority of groups South Georgia and Shag Rocks presented a faunal mixture of Magellanic and Antarctic forms together with a group of endemics. Cailleux pointed out, a fact all too often forgotten, that the degree of endemism of the Antarctic fauna depends very greatly on whether South Georgian species are included in or excluded from, the Antarctic Region. This problem will be discussed more fully in a discussion on endemism later in this contribution. Following what seems to be a consensus of modern opinion the Antarctic benthic region is accepted for purposes of the present work as extending to South Georgia. On the little evidence available Bouvet Island is also included. However, Heard, Macquarie and Kerguelen Islands which fall within or straddle the Convergence, are considered on the faunal evidence to be essentially Subantarctic, although some elements of the Antarctic fauna reach these islands.

B. Terminology It is impossible not to touch on some matters of terminology. The whole question of the nomenclature for basic divisions in the southern regions is gradually becoming more confused. Hydrological usage has been based upon the characteristics of the water masses extending in concentric belts from the Antarctic Continent. The Antarctic water closest to the Continent separated from the next water mass, Subantarctic water, by the Antarctic Convergence, the Subantarctic water separated in turn by a Subtropical Convergence from Subtropical. There may well be anomalies in this usage but it has served southern hydrographers well and several generations of southern biologists have been trained in the basic patterns and used them to interpret plant and animal distribution patterns. Biologists cannot complain if growth in oceanographic knowledge demands a change in these basic concepts, and perhaps we must learn to accept the “Antarctic polar front )’in place of the “Antarctic Convergence )’, and the presence of the Subantarctic Divergence between the Antarctic Convergence and the Subtropical Convergence. It is to be hoped that physical oceanographers will remember that many other scientists wish to use their results and refrain from changes in nomen-

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clature solely for the sake of semantics. Biogeography has already bedevilled itself in the search for better words, rather than better concepts. The term “ Subantarctic ” was apparently introduced by plant geographers around the turn of the century and soon came into common use in a collective geographical use, as in Chilton (1909). It was also taken over by hydrologists. The terms Antarctic and Subantarctic have been in common usage in discussions of southern biogeography for many years. Ekman (1935), in his classic book on marine zoogeography, and perhaps with more effect in the English (1953) translation, advocated a usage corresponding to that in the Northern Hemisphere, and coined the term “Antiboreal ” to replace “ Subantarctic ”. Oceanographers have not used Ekman’s proposed “Antiboreal Convergence ” to replace the “ Subtropical Convergence ”, and the term Antiboreal has gained little acceptance. Several Soviet authors have used the term “ notal ” (Vinogradova, 1962; Andriashev, 1965) instead of “ Subantarctic ” for the area between the Convergences. Hedgpeth (1970) has been rather scathing about the term “ notal ” and such derivatives as “ notalian ”. Knox (1960) influenced no doubt by the general title of the symposium to which he was contributing, used the term “ cold-temperate ” and sometimes “ Subantarctic cold-temperate ” for Subantarctic surface water. There does not really seem to be a case for uniform practice in naming major northern and southern zones, particularly in relation to marine biogeography. Southern Hemisphere conditions are not the same as comparable latitudinal zones in the Northern Hemisphere, and the basic difference between the relationships of water to land masses in the two polar areas precludes any chance of fruitful close comparison. Workers in the Northern Hemisphere, who are the main critics of “ Subantarctic ” and the main protagonists for uniform nomenclature between the hemispheres, might first consider that while the parallel of 55”s cuts through Tierra del Fuego and that there are no permanently inhabited areas south of this (much less cities), the parallel of 55”N leaves the northern tip of Ireland and the cities of Glasgow, Edinburgh, Copenhagen and Moscow somewhat to the north, with Oslo, Stockholm and Helsinki well to the north. Human habitation patterns are very different in the two hemispheres, are not most other factors also different? Hedgpeth (1969) came out very strongly in favour of the terms “Antarctic ” and “ Subantarctic ”, as would many marine biologists, especially in the Southern Hemisphere. The whole matter seems to be causing fresh discussion at present between workers concerned with terrestrial biogeography who find a need to subdivide “ Subantarctic ”

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Islands into two different categories. Whatever decision is reached in this field, marine biologists will probably continue using “ Subantarctic ” as long as hydrographers retain the term. C . Subdivisions of the Antarctic Region Some of the problems encountered in attempting to limit the Antarctic Region, also make subdivisions of the Region difficult. A number of schemes have been proposed. Regan (1914b),discussing the distribution of Antarctic fishes, separated coastal from oceanic fishes. It is in fact difficult to separate benthic fishes sharply from other forms, since many of them have larval stages which are pelagic and many of the adult species which would normally be considered as benthic have been taken quite frequently in mid-water. Considering coastal fishes alone Regan postulated three zones : 1. South Temperate Zone ; 2. Subantarctic Zone ; 3. Antarctic Zone with two districts, Glacial and Kerguelen.

Regan’s Antarctic Zone included, “ t h e coast of the Antarctic continent and the islands that lie south of the isotherm of 6OC, with the probable exception of Macquarie Island ”. The Glacial District comprised the coast of the Antarctic Continent and all the adjacent islands lying within the extreme limit of the pack ice, including South Georgia, the South Sandwich Islands and probably Bouvet Island. He believed that any subdivision of the Glacial District was premature. The Kerguelen District included Kerguelen and Heard Islands, the Crozets, Marion and Prince Edward Islands. Regan (1914) was followed with approval by Norman (1938) when he argued that the fish fauna of Kerguelen-Macquarie was so different from that of the Patagonian Region and “ the Antipodes ” that i t ahould be included in the Antarctic Zone as a separate district. Waite (1916) combined Regan’s classification with a geographical one and divided the whole southern ocean into four quadrants : 1. Australian Zonal Quadrant (Victoria Quadrant) ; 2. Pacific Zonal Quadrant (Ross Quadrant) ; 3. American Zonal Quadrant (Weddell Quadrant) ; 4. African Zonal Quadrant (Enderby Quadrant).

The resultant Quadrant-Zone-District classification, although based upon logical 90’ divisions, had of course no biological significance. The

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R. K. DELL

fact that one boundary cuts the Ross Sea shows the difficulty of using such a scheme. At the same time a number of workers trying to record and analyse the distribution of organisms around the Antarctic Continent have used this scheme or a modification of it to codify their distributional data. Ekman (1935, 1953) largely on the basis of surface water temperatures subdivided the Antarctic Region into " High Antarctic " and " Low Antarctic ". Hedgpeth (1970) has pointed out that Ekman used the terms " region '' and " province " almost interchangeably in the English translation (1953). Norman (1938), again considering fishes utilized Regan's scheme, together with the Quadrants. He did not believe that the evidence allowed any subdivision of the Glacial District. Nybelin (1947) working also with fishes subdivided the Antarctic Zone as follows : 1. High Antarctic Region, the coasts of the Antarctic Continent and associated islands. A. East Antarctic Subregion. B. West Antarctic Subregion. 2. Low Antarctic Region, South Georgia and Shag Rocks. He showed that the South Sandwich Islands and Bouvet were both related to the West Antarctic Subregion and to the Low Antarctic Region, with an additional independent character. The subdivision into East and West Antarctica, commonly used by geologists is an extremely useful subdivision particularly if used in a non-committal sense. The longitude of Greenwich and the equivalent line of 180' divides Antarctica unequally into two sections, the western section largely taken up with the Weddell and Bellingshausen Seas and the Antarctic Peninsula which together with the islands of the Scotia Arc has its own biogeographic features. The boundaries should not be taken too precisely because once again 180' longitude bisects the Ross Sea (which surely belongs faunally to East Antarctica). The fauna off the coast of Marie Byrd Land and the Amundsen Sea is so poorly known that it can serve at present as a no-mans-land type of boundary. Similarly the fauna from the eastern shores of the Weddell Sea and off Crown Princess Martha Land is hardly known. The term West Antarctica is a very useful one in a strictly geographical sense as a kind of shorthand for, " the Weddell and Bellingshausen Seas, together with the Antarctic Peninsula and the associated islands of the Scotia Arc ". It is in this sense, and with the boundaries purposely left indefinite that the term " West Antarctica " is used throughout the present work.

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11

Powell (1951), considering molluscs particularly, discussed some of the history of subdivision into biogeographic zones, and used the term “ province ’) for the units. He considered it undesirable to formulate a comprehensive scheme. He did, however, nominate a Georgian Province for the South Georgia-Shag Rocks area. I n later work (1965) he did not modify this scheme in relation to the Antarctic. Knox (1960) proposed a subdivision of the Antarctic Province into Rossian and Scotian Subprovinces with a distinct South Georgian Province. The Rossian Subprovince comprised Victoria Land and the Ross Sea area of East Antarctica. The evidence for his separate rank for the Rossian Subprovince was the lack of many Magellanic species, the fact that the algae Ascoseira mirabilis and Cytosphaera jaquinotii had not been recorded, and the distinct Australasian affinities shown by the occurrence of algae such as Gigartinu apoda. The Scotian Subprovince comprised Graham Land, the South Shetlands, South Orkney and South Sandwich Islands. The South Georgian Province was based largely on algal evidence, quoted from Skottsberg (1941), which allied South Georgia to the Falklands. The only zoological evidence quoted was Powell’s (1951) statement that the molluscan fauna of South Georgia is distinctive with little in common with that of the Falklands. Knox therefore considered that South Georgia is best considered transitional between the Antarctic and Subantarctic cold temperate. Knox’s treatment shows the difficulties in applying the concept of biological provinces in general, and in reference to the Antarctic, especially widely separated island groups in particular. He, himself, (Knox, 1960, p. 611) was quite clear that he was discussing a subdivision for the littoral zones of the Antarctic and southern temperateregions. Other workers using his scheme subsequently have not always realized this limitation. Kusakin (1967) commented on the difficulties in comparing Subantarctic and Antarctic faunas as follows : “An important failing in ow analysis (of which we are well aware) is that we examine entirely different fauna, namely, littoral, sublittoral, pseudo-abyssal and bathyal. However, this is at present unavoidable . . . although it is certain that the boundaries of the biogeographical zones for all these zones do not and usually should not coincide ”. It is unfortunate that all workers on marine biogeography do not see the issues so clearly. He also comments on the difficulty of comparing the faunas of the Antarctic and of other areas because of the absence of littoral isopods on Antarctio shores, and because the shelf fauna which elsewhere occurs down to depths of 150-200 in, here descends to between 400 and 700 m. Unfortunately Knox does not always seem to realize that the only littoral evidence that would be available for the Antarctic Region would

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R. K. DELL

be confhed to the islands of the Scotia Arc and part of the Antarctic Peninsula, there being no littoral to speak of exposed in the rest of the Antarctic Continent (what little there is will be highly specialized and largely confined to a crevice biota). This is not quite so vital in regard to the algae, but some of the animals cited as characteristic of the Antarctic Province are unfortunately chosen, to say the least. Even Powell’s remarks on the molluscan fauna of South Georgia, and cited by Knox, refer to the fauna as a whole, deep-water forms as well as littoral species. Andriashev (1965) discussed Nybelin’s scheme and although allowing that more recent work has borne out the distinctions between East and West Antarctica, and that these are significant and at present inexplicable, does not believe that the distinction between the High and Low Antarctic Regions can be maintained. South Georgia has some elements of endemism and some negative features and thus merits some degree of biogeographic subdivision, but not at the level of a separate Region or Subregion. Andriashev attempted a synthesis of previous work in the light of the additional distributional evidence available. The following were included in Andriashev’s Glacial Subregion of the Antarctic Region. 1. Continental Province (= High Antarctic Region of Nybelin). Includes the South Shetland and South Orkney Islands. A. East Antarctic District. B. West Antarctic District. 2. South Georgia Province

The Kerguelen Subregion included Marion, the Crozets, Kerguelen, Heard and Macquarie Islands. Andriashev’s description, “ They have an impoverished, mosaic fauna of an insular type with a considerable percentage of local endemism ”, seems to sum up the situation of this area very aptly. Kusakin (1967) working with isopods proposed divisions essentially similar to those of Andriashev except for different usages of category names, i.e. ‘‘ subregions ” and “ provinces ”. The evidence available to him forced a subdivision of the Antarctic Continent into Pacific Ocean (or Ross) and Indian (or Davis) districts. Kusakin also restricted West Antarctica to Graham Land together with the South Shetland and South Orkney Islands. In his figure showing his proposed Antarctic biogeographical divisions Kusakin includes sections of the Weddell and Bellingshausen Seas so that his view of East Antarctica is essentially identical with that used by the writer in the present work. Kott (1969a, p. 194) adopts a classification based upon a study of

ANTARCTIC BENTHOS

13

ascidian distribution which is essentially the same as that put forward by Knox (1960). 1. Antarctic Subregion

A. Continental Province (Antarctic Peninsula to Weddell Sea). B. South Georgian Province (Bellingshausen Sea, Antarctic Peninsula to South Georgia). 2. Subantarctic Subregion

A. Magellanic Province (South Georgia to Patagonian Shelf). B. Kerguelen Province. C Antipodean Province. This scheme is a little uncertain in its application since the Antarctic Peninsula occurs in two provinces, as does South Georgia. Kott is obviously uncertain of the correct location for South Georgia. To name a province " South Georgia " and then t o exclude South Georgia from it perhaps indicates that the provincial concept can cause difficulties in itself. Hedgpeth (1969) proposed a broad scheme as a synthesis of divergent views. This accepted a Subantarctic and an Antarctic Region. The Antarctic Region essentially fitted within the Antarctic Convergence except where the Kerguelen Subregion of the Subantarctic cuts across its northern boundary. The Subantarctic Region covers the southern portion of the area covered by Subantarctic Surface Water. The Antarctic Subregion was divided into a Continental (or High Antarctic) Subregion (or Province) with two extensions, and a Scotia Subregion with South Georgia separated as a distinct District (Fig. 1). The writer has discussed the validity of the concept of marine provinces (Dell, 1962), has argued against fine distinctions in the Antarctic Region at our present stage of knowledge (Dell, 1965) and has shown the Wculties of fitting isolated islands such as Macquarie into a provincial pattern. He has also (Dell, 1956) shown that in New Zealand the distribution of the archibenthal molluscan fauna (200-600 m) bears little relationship to the distribution patterns developed on the shelf. I n spite of the number of workers who have discussed marine provinces, there are remarkably few definitions of a province, and most definitions that have been put forward are expressed in very general terms. A major factor in limiting a province must be a barrier which will act on all organisms in a similar way causing a large number of geographic ranges to cease at about the same point. With marine organisms such a barrier will need to be a wide deep-water gap, sudden marked changes in temperature or an extensive land mass.

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FIQ.1. Biogeographio divisions as used in the present work (adapted from Hedgpeth, l909),showing essentially the three oonoentrio zones of the High Antarotio Region, the Antarotio Region (essentially referring to plankton) and the Subantarotio Region. 1. Megellado; 2. Tristen de Cunha; 3. Kerguelenian; 4. Continental Antarotio; 5. South Ueorgien Distriot.

It is difficult enough to define provinces for one group of plants or animals. To find common provincial boundaries for many different groups of animals has not proved an easy task. Since littoral distribution patterns may not correspond with those on the shelf or in deeper

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16

water, the term " province " will probably always require qualification in some way. The terms " littoral algal province ", or " shelf molluscan province " may have some relevance, but a " Rossian marine province " can only be the result of the sum of many compromises, and thus have little real meaning. The compilation of detailed geographical and bathymetrical ranges is of far more value for studies on distribution, than discussions about systems of provinces. There is evidence that discussing distribution in terms of provinces leads biologists into fundamental errors of outlook. There is always a tendency to consider that the fauna of a province is uniformly distributed throughout an area, or that the province has some objective validity of its own. It is often claimed that additional records for the distribution of a species shows that it has extended its range to an additional province. Isolated areas such as South Georgia, or Kerguelen or Macquarie Island are always difficult to fit into a provincial concept. For example the statement that a species occurs in the Kerguelenian Province does not tell the reader very much. It may occur on Kerguelen, or on Macquarie or on both. It may also occur in the Ross Sea or on South Georgia. A more useful piece of knowledge would be that the species has been recorded from off Kerguelen in depths from 10 to 76 m and in the Ross Sea in 300 m. The kind of information we do require for biogeographical discussions is the type of detailed distribution records presented for the marine algae by Papenfuss (1964) and for ascidians by Kott (1969). Even in groups such as these the distributional evidence available to us still indicates the areas in which the major expeditions have worked rather than the actual distribution of the organisms concerned. The study of actual distribution patterns seems a far more useful biological exercise than division of an area into provinces, districts, regions or zones, and into subdivisions of these with groupings into hierarchies of relationship. This method of approach seems doubly necessary in areas where there is obviously a dynamic ebb and flow of species in several directions as there undoubtedly is through the islands of the Scotia Arc. The major part of the shelf fauna of the Antarctic seems effectively cut off from the rest of the world by the major barrier of the Southern Ocean. The one area where the barrier starts to break down is the Antarctic Peninsula and the associated sections of the Continent. The stepping stones of the islands and island shelves of the Scotia Arc here supply a pathway between the Antarctic and South America which different organisms have used to varying degrees. It is precisely in this area that most discussion about faunal subdivisions occurs, where the boundaries proposed by previous workers are shifted and where

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problems of definition are more difficult. Here especially a study of the dynamics of biological migration will surely prove more fruitful than the static studies which working within a provincial concept often engender.

D. Endemism Most systematists dealing with Antarctic organisms are interested in the degree of endemism. Some few have been strong minded enough not t o calculate the percentage, or at least not to publish the results. Most of us, while admitting the incomplete data with which we work, persuade ourselves to carry out the exercise and publish the results. The degree of endemism is of course of special interest for the Antarctic since it is one of the few " objective " measures we have for the degree to which the Antarctic fauna and flora has been isolated, and thus a measure of the age of the biota. As such these calculations are beloved by biogeographers. One biogeographer has recently assembled a long list of the endemism percentages (Cailleux, 1961) given by authors for Antarctic plants and animals, recent and fossil, marine, freshwater and terrestrial. A somewhat modified extract from this list as it relates to Antarctic benthic organisms is given in Table I. There are now more up to date figures for some of these groups, but Cailleux had demonstrated that taking the figures given by subsequent workers for any one group may have changed the actual figures but the general order of magnitude remains roughly the same. Some successive percentages for a few groups illustrate this point (Cailleux, 1961). Sponges Pycnogonids Ascidians Marine isopods

42 84 57 45

44 80

67 80

67% 91%

a4y0 78%

The general high percentages listed by Cailleux ranging from 31 to 96% for a large number of animal groups bears striking testimony to the independent character of the Antarctic fauna. Cailleux even gave mean values for marine organisms (67%), terrestrial organisms (57y0), marine fossils (60%) and terrestrial fossils (62%). Whatever precise value such calculations may have, the figures are remarkably consistent and they are remarkably high. It is hard to escape the belief, when considering degrees of endemism of this magnitude, that the biota of the Antarctic has been isolated for a long time. Whatever the history of the presence of a modern migration route in the form of the Scotia Arc, two conclusions seem inevitable:

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ANTARCTIO BENTHOS

TABLEI Group Littoral fishes Ascidians Holothurians (littoral) Holothurians (abyssal) Echinoidea Echinoidea, Ophiuroidea, Asteroidea (littoral) Echinoidea, Ophiuroidea, Asteroidea (abyssal) Ophiuroidea Asteroidea Crinoidea Pycnogonida Isopoda Mollusca Gastropoda Bryozoa Bryozoa, Stenolemata Nemertea Polychaetes Actiniaxia and Zoantharia Actiniaria Scleractinian Corals Octocorals Hydroids Hexactinellid sponges Sponges (Calcarea) Sponges Phaeophyceae Rhodophyta

Author Regan Norman Hartmeyer Vaney Vaney Mortenseri Koehler Koehler Hertz Fisher John Hodgson Richardson Lamy Strebel Rogick Hastings Borg Joubin Ehlers Carlgren Pax wells Molander Billard Schulze Bronsted Burton Skottsberg Kylin

(yo) Number of species listed Endemic 49 54 44 39 18 27

96 90 84 85 67 82

106

77

52 89 52 16 77 49 30

75 76 69 76 91 78 64 73 89 84 42 84 31 87 86 60 66 55 77 73 67 46 30

26

36 37 24 19 36 16 22 10 16 37 26 52 200 13 20

(1) plants and animals of the southern hemisphere have their dispersal effectively stopped by water temperatures below O'C, and (2) plants and animals adapted t o Antarctic water temperatures, on the whole, cannot efficiently migrate into warmer water.

Cailleux raised one extremely important point in relation t o the degree of endemism especially when considering the odd situation demonstrated by the biota of South Georgia. It is obvious, when one has had the point demonstrated, that if one includes the total fauna of

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R. K. DELG

South Georgia in the Antarctic region, one must include a large number of Magellanic and Subantarctic species which k d their southern limit in South Georgia. If one uses such a list to calculate the percentage of endemism, the total number of Antarctic species becomes unbalanced. On the other hand if South Georgia is rigorously excluded from the Antarctic, then many species cannot be claimed to be Antarctic endemics. Cailleux solves his immediate problem for his analysis by excluding the northern species which also occur in South Georgia from his calculations, and by classing as endemic to the Antarctic those species which also occur in South Georgia. South Georgia is perhaps the most difficult problem in analysing the relationships of Antarctic fauna, but it really only points the self evident fact that the percentage of endemic forms will alter with the boundary accepted for any particular region. The percentage of endemism found in any particular square kilometre will be O%, the percentage for the whole world must be 100% (Cailleux, 1961). 111. HISTORY OF BENTHIU INVESTIGATIONS An extremely large number of expeditions of one sort or another have visited Antarctica. Roberts (1958) has provided a magnificent source of information in listing them up to the beginning of the International Geophysical Year in July 1957. The earliest beginnings of human intrusion into Antarctic waters are poorly documented and will probably never be better known. Proper documentation really begins in the 1770s when the fringes of Antarctica began to be explored as part of the general exploration of the Southern Hemisphere and the southern Indo-Pacific in particular. Two French expeditions skirted the Subantarctic with Kerguelen-Tremarec (1 77 1-72) discovering Kerguelen Island, and Marion-Dufresne (1771-72) Prince Edward Islands and Iles Crozets. The Antarctic Circle was f2st crossed by literate man on 17 January 1773 in about longitude 39"E by the two vessels, Adventure and Resolution on the second voyage of Captain James Cook. The circle was crossed several more times on this expedition which reached 7lo10'S, charting South Georgia and discovering the South Sandwich Group. The results of Cook's voyage were largely geographical in relation to the Antarctic, although observations were carried out on birds. Certainly no benthic Antarctic animals were recorded. Following accounts of Cook's discoveries British sealers began to exploit seals at South Georgia in 1778, to be followed rapidly by American interests. As seals of one species or another were decimated in one area, operations were extended from the Falklands to South Georgia,

ANTILBUTIU BENTHOS

19

the South Orkneys and the South Shetlands. The position of all the major Subantarctic and Antarctic island groups were largely determined or confkmed during this period of intensive sealing activity around the close of the eighteenth and the beginning of the nineteenth centuries. I n 1821 Palmer sighted the Antarctic Peninsula (Graham Land, or the Palmer Archipelago). British sealers, particularly James Weddell and the vessels of the Enderby company carried out much useful geographical work on the American sector and later in the New Zealand and Australian Subantarctic islands. Many of the geographical results of these excursions were at first kept as tight commercial secrets but eventually appeared on charts, available to all. But very little biological knowledge resulted from all these traffickings, except as they related to the body of lore on seals, whales and penguins which were utilized commercially, or to the other obvious birds of the area. The first government sponsored United StatesAntarctic exploring expedition was under the command of Benjamin Pendleton, but with other ships commanded by Nathaniel B. Palmer and Alexander S. Palmer, one or other vessel of which visited the South Shetlands in JanuaryFebruary 1830. The expedition was accompanied by several independent investigators, one of whom was Dr James G. Eights, who collected shells andcrustacea. One of the shells was described by J a y (1839), from a Couthouy manuscript, as Nucula eightsi (now Aequiyoldia eightsi). Eights himself published several papers describing other animals from the South Shetlands, most of which have proved to be important Antarctic species. The first in 1833 described Brongiartia trilobitoides (now Serolis trilobitoides according t o Sheppard, 1933). I n another paper Eights (1852) described the giant isopod, Glyptonotus antarcticus, whose important ecological position around Antarctic coasts is only slowly being realized. Perhaps the most interesting of these finds was the ten-legged pycnogonid, Decobpoda australis (Eights, 1835). At the time the very idea of a ten-legged pycnogonid seemed a contradiction in terms, and Eights’ description was largely ignored, when it was not tacitly considered to be an error of observation. Hodgson, on Scott’s first expedition was to collect a very different pycnogonid with five pairs of legs from the Ross Sea, and the following year (1905) recognized Dewbpoda austraZis among material collected by the Scottish National Antarctic Expedition. Eights remarkable pycnogonid thus had to wait for 70 years before it was recognized again and made respectable. Calman (1937) gave an interesting account of Eights’ career as far as known and reproduced the original figures of Decolopoda, Glyptonotus and Serolis. Eights died in obscurity. It is perhaps fitting that this first naturalist to describe some of the charac-

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teristic Antarctic benthic animals should now have a United States base in Ellsworth Land bearing his name. Bellingshausen's fine Russian expedition ( 1819-21) circumnavigated the Antarctic Continent, but again the major discoveries were geographical and because the account of the expedition appeared in Russian the results were slow in percolating through to the rest of the world. During the years 1839 and 1840 three different national expeditions were in the Antarctic, and although they all had great potential for collecting biological material, and although they all produced reports on biological material, collected mostly outside the Antarctic, none of them seems to have contributed significantly to our knowledge of the Antarctic benthos. Dumont D'Urville (1837-40) with the two corvettes Astrolabe and La Z&e operated south of Cape Horn in 1838, and surveyed the South Orkneys, the South Shetland5 and parts of the Antarctic Peninsula. Bate (1862) described three species of amphipods collected at the South Orkneys by La ZdZde. In 1840 D'Urville discovered Adelie Land and was off the Wilkes Coast just a few hours after Charles Wilkes of the United States Exploring Expedition. The United States Exploring Expedition under Charles Wilkes ( 1838-42) with five ships again carried out geographical investigations over a wide area of the Antarctic. Extensive biological results were produced based on the collections made in the tropical Pacific and in the Subantarctic but again no marine benthic animals appear to have been recorded from the Antarctic. Sir James Clark Ross (1839-41) with the Erebus and Terror especially equipped for magnetic observations, circumnavigated the Antarctic Continent. His ships broke through the pack ice of the Ross Sea, thus opening a gate through which many subsequent expeditions were to work their way south to the Ross Sea and the Continent. Ross made many geographical discoveries and confirmed the positions of many other features. Thanks t o the presence on board of the botanist, J. D. Hooker, this expedition laid the major framework for all subsequent work on southern floras, particularly of the Subantarctic Islands. Contributions to knowledge of Antarctic benthos appear to have been rather minimal. Had the animals collected been recorded in a single publication, the results of the Antarctic work might have had more impact. It is, however, extremely difficult to track down papers based on collections from the Erebus and Terror. Ross (1847, vol. 1, p. 199) recorded that near 72'87'5, 176'6% on 18 January 1841 from 230 fm, " Small stones and shells, with some pieces of coral and a crustaceous animal (Nymphn gracile), common in

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ANTARCTIC BENTHOS

the Arctic Seas, came up with the lead ”. Later (1847, vol. 1, p. 201) Ross recorded the result of a dredge haul in 270 fm at 72”31’S, 173”39’E. Besides a large block of granite and many stones, beautiful specimens of living coral and other animals were obtained. “ Corallines, Flustrae, and a variety of marine invertebrate animals, also came up in the net, showing an abundance and great variety of animal life. Among them I detected two species of Pycnogonum ; Idotea Baffini, hitherto considered peculiar to the Arctic Seas ; a chiton, seven or eight bivalves and univalves, an unknown species of Gammarus, and two kinds of Serpula, adhering to the pebbles and shells ”. In an appendix to Ross’s work Charles Stokes (1847) described and indicated several new species of “ corals )’, Hornera lateralis (Bryozoa), Retepora cellulosa (Bryozoa), Primnoa Rossii (Alcyonaria),Melitoea australis and MadreporaJissurata. It was stated that drawings of these new forms would appear in the Zoology of the voyage but only descriptions of vertebrate animals appear to have been published in the official results of the Expedition, and Stoke’s names seem to have been largely ignored. Ross’s account seems to be the first account of a collection with a dredge in Antarctic waters. Hooker (1845) contributed a slightly different account of the same collecting episode, but was mainly concerned to show that life existed at depths greater than 300 fm. Baird (1865, 1870) described some polychaetes from this material, e.g. Terebella Jlabetlum, T. bilineata, Eunice narconi and 8erpula narconensis. Carter (1872) described two new species of sponges from material in the British Museum collected from 300 to 206 fm respectively. Ehrenberg (1844) recorded some foraminiferans from the Ross Sea material. Bate (1862) described two amphipods from expedition material collected from Hermite Island, off Tierra del Fuego. Other forms have probably been described by various workers. The ones outlined above are the only papers to come to the writer’s attention. There was then a long hiatus period in biological activity in the Antarctic, to be broken by the H.M.S. Challenger (1872-76). The magnificent set of volumes recording the biological results of this expedition described many southern high latitude animals from the plankton and from the benthos especially in the vicinity of Kerguelen, Prince Edward Islands, the Crozets and Heard Island. The Challenger penetrated to 66’40’5 in latitude 7S022’E, the first steam vessel to cross the Antarctic Circle. The appearance of the biological results of the Challenger Expedition mark the end of a period of biological exploration that can rate as little more than preliminary skirmishing with the problem. Many Antarctic benthic animals were described as a result of the Challenger’s investigations but these were mostly species which also occurred in the

. .-

A. M B I0

a

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k. K. DELL

Subantarctic. Up to this period there were extremely few records of Antarctic benthic animals as such. The Challenger collected benthic animals at three stations south of SO'S, i.e. at Station 152 at 60'52's in 1 260 fm (2 304 m), obtaining an ophiuroid, holothurians, an isopod, a macruran, a gastropod and one fish ;Station 153 a t 65'42'5 in 1 675 fm ( 3 063 m) and Station 156 at 62'26's in 1 975 fm (3 611 m). At both these latter stations a range of benthic animals was collected. These stations are all, however, at abyssal depths and hardly warrant consideration as Antarctic animals. Apart from the German International Polar Year Expedition (1882-83) which wintered at South Georgia, it was not until the closing years of the nineteenth century that the first real collections of Antarctic bottom animals were made. The first two decades of the twentieth century were to see a great flood of expeditions, many of them with biological programmes. One problem in writing a consecutive account of investigations into the Antarctic fauna arises from the fact that dates of publication of scientific results may bear little relation to the date of the expedition. The earlier expeditions did not amass very large collections and their biological reports running to a single volume or at most a very few volumes could be brought out quickly after the close of the expedition. Those expeditions which concentrated upon biological work and which obtained large collections could no longer hope for such rapid publication. Thus the biological results of the British-Australian-New Zealand Expedition (B.A.N.Z.A.R.E.), which was in the field from 1929 to 1931, are still appearing moderately regularly. The Belgian Antarctic Expedition under Adrien de Gerlache de Gomery in the Belgica (1897-99) appears to be the first expedition to sample the Antarctic benthos proper, working around the South Shetlands, the Antarctic Peninsula and the Bellingshausen Sea. And now the flood gate was open. The 1898-1900 British expedition under Borchgrevink in the Xouthern Cross besides being the f i s t scientific expedition purposely to winter on the Antarctic continent, collected marine animals from the Ross Sea, publishing the results in a single volume. The German Antarctic Expedition (1901-03) under Drygalski in the Gauss made large collections especially from the Gauss Winter Station in the Davis Sea. The Swedish South Polar Expedition (190104) under Nordenskjold maintained a comprehensive biological programme at South Georgia and off the Antarctic Peninsula. Some collections were lost when the Antarctic was crushed in the pack. The British National Antarctic Expedition (1901-04) under Captain Scott in the Discovery collected extensively in the Ross Sea. The

ANTARUTIU BENTHOS

23

reports laid the basis for an understanding of the marine animals of the Ross Sea. The Scottish National Antarctic Expedition under W.S. Bruce in the Scotia carried out the first oceanographic exploration of the Weddell Sea, and also collected benthic animals from the South Orkneys and the Palklands. Bibliographically the reports can cause confusion since most were published first in Scottish scientific journals, before being republished later as expedition reports with changed pagination. The French Antarctic Expedition under Charcot in the B a n p i s carried out an extensive biological programme off the western coast of the Antarctic Peninsula, working its way to within sight of Alexander Island. The British Antarctic Expedition under Shackleton in the Nimrod wintered at Cape Royds in the Ross Sea. An attempt was made to publish a series of scientific results but government support was lacking and publication lapsed. Papers by Hedley (1911) on molluscs, Waite (1911) on fishes and by Koehler (1911) on echinoderms were the major ones to appear on benthic animals. A useful list of scientific results from this and subsequent Shackleton expeditions was published by J. M. W(ordie) and B. B. R(oberts) (1943). The Second French Antarctic Expedition again under Charcot was carried out in what was surely the most suitably named vessel for any expedition, the Pourquoi Pas? The biological programme was again concentrated along the west coast of the Antarctic Peninsula and through the Bellingshausen Sea to within sight of Peter I Island. The British Antarctic Expedition (1910-13) under Scott in the Terra Nova was to end in heroic tragedy. Biologically it proved very productive and the series of reports added significantly to knowledge of the benthos of the Ross Sea. The Australasian Antarctic Expedition (1911-14) under Mawson in the Aurora was to be the last in this spate of Antarctic endeavour. The biological results have been amongst the most fruitful of any of the early expeditions although some were not published until much later. The onset of World War I and its depressing aftermath drew a blackout curtain across the Antarctic, at least in respect of the major expeditions required to obtain marine biological results. When the curtain lifted it was to usher on to the Antarctic scene a completely new era of biological investigation. From 1925 until at least 1939 biological work in the Antarctic was dominated by the activities of the Discovery Investigations. Hardy (1967) in his book Great Waters, possibly the best semi-popular account of a large scale expedition and the work of marine biologists, traces the

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history of the Discovery Investigations and supplies a most useful contents list to the 34 volumes of Discovery Reports (some 13 000 pages of scientific reports). Previous biological efforts in the Antarctic had all been based upon short term expeditions. The Discovery Committee planned its work as a continuing investigation. Early work was concentrated on major whaling areas such as South Georgia but the work was slowly extended to embrace the whole of the Antarctic ocean. The old R.R.S. Discovery, and R.R.S. Discovery 11 and R.R.S. William Scoresby achieved an enviable record of scientific work between 1925 and 1937. I n 1949 The Discovery Investigations were taken over by the National Institute of Oceanography. Discovery 11 made one more extensive Antarctic cruise in 1950-51 to give a tally of a quarter of a century of active investigation into Antarctic marine biology. However, the collections are by no means fully described and new Discovery Reports appear year by year. The Discovery Investigations were initiated in order to understand the biology of the commercial whales in the Southern Ocean. It is understandable, therefore, that physical oceanography and the world of plankton should be the fields to attract most attention. In fact in spite of the great extent of the Discovery Reports, a relatively small amount has so far been published on the benthos as such. In the meantime several other expeditions had entered the field. The Norwegian Antarctic Expedition (1927-28) under Haakon Mosby on the Norvegia visited Bouvet Island, South Georgia, the South Shetland5 and the Antarctic Peninsula, and in 1928-29 landed on Peter I Island. Three volumes of scientific results have been published, interesting because a number of authors considered biogeographical problems in detail and attempted to review the state of knowledge in their groups. Holtedahl (1935) gave a brief account of these rather complicated expeditions, of which results were still appearing in 1961. A small German expedition under L. Kohl-Larsen collected in South Georgia in 1928-29. Between 1929 and 1931, the British Australian, New Zealand Antarctic Research Expedition (B.A.N.Z.A.R.E.) under Mawson in the Discovery carried out a most productive biological programme which has added appreciably to our knowledge of the benthos in Antarctic waters between about 45°C and 130"E. This ship Discovery was a veteran of Antarctic exploration, having been built especially for Scott's 1901-03 expedition, and later, having initiated the work of the Discovery Committee, became the base for the B.A.N.Z.A.R. Expedition. This is the vessel which, moored on the River Thames in London, now serves as a memorial to Captain Scott. Ten volumes of

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biological results have so far appeared from this expedition. A very useful summary by Johnston (1937) gives an account of the biological organisation of this expedition together with a station list. The British Graham Land Expedition (1934-37) carried out an extensive biological programme, though little relating to marine biology has yet been published. The onset of World War I1 did not effectively close down all Antarctic activity. The United States Antarctic Service Expedition (1939-41) established two bases, one at Marguerite Bay, Antarctic Peninsula and the other in the Ross Sea. Biological results were not extensive. The period 1940-45 saw the development of almost comic opera moves and countermoves as British and Argentinean parties sought to establish their own claims to the islands of the Scotia Arc and to the Antarctic Peninsula. Science often suffers from political comic opera but in this case science gained through the establishment of occupied bases and the maintenance of scientific programmes. The British endeavour was mounted under the code name of " Operation Tabarin ". Most of the biology was terrestrially oriented and few of the marine collections obtained have been written up separately. From 1947 onwards Argentinean and Chilean claims were consolidated by annual expeditions matched by similar activities on the part of the Falkland Islands Dependencies Survey by the United Kingdom. The United States Navy mounted operation " Highjump " in 1946-47 and this was followed by the Ronne Antarctic Research Expedition (1947-48). I n 1947-48 the Australian National Antarctic Research Expedition was inaugurated. Little marine biology was achieved by any of these endeavours. The next major phase in Antarctic scientific exploration was the International Geophysical Year (1.G.Y.) organised by the International Council of Scientific Unions (I.C.S.U.). The year was planned for 1957-68 but planning began in 1952, and special attention was directed towards Antarctic research. The scheme for the I.G.Y. with manned stations around the Antarctic Continent was taken up enthusiastically by many nations. Several countries were involved in preliminary reconnaisance expeditions often primarily planned to choose suitable sites for I.G.Y. bases. Thus the United States series of " Deep Freeze " operations commenced in 1955-56, and a Soviet I.G.Y. expedition was mounted in 1955-56. I.G.Y. bases up to 1958 had been established by the United States, United Kingdom, the U.S.S.R., Australia, New Zealand, France, Belgium, Norway and Japan. Twelve nations signed the

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Antarctic Treaty in 1959. A committee of the International Council of Scientific Unions (I.C.S.U.), the Special Committee on Antarctic Research (S.C.A.R.) formed in 1958, has held conferences, organized subcommittees to stimulate further work, and acts as a scientific advisor to the Treaty nations. Some nations continued to maintain bases in Antarctica after the close of the I.G.Y. These have included Argentina, Australia, Chile, France, Japan, New Zealand, South Africa, United Kingdom, U.S.S.R. and the United States. Marine research programmes have been instituted at many of these bases, especially McMurdo Sound (U.S.A. and N.Z.), Adelie Land (France), Mirnyy (U.S.S.R.), Signy Island, South Orkneys (U.K.). With a few exceptions the most productive programmes have resulted from the use of expedition vessels to work in associated areas. The United States efforts have been organized by the U.S. Antarctic Research Program (U.S.A.R.P.) appointed under the auspices of the National Science Foundation. Since 1962 the U.S.N.S. Eltanin operated by the United States National Science Foundation has been operating an almost continuous collecting programme through the Southern Oceans. The results of many of these more recent endeavours insofar as they relate to the benthos are only slowly appearing. The New Zealand Oceanographic Institute is publishing a series of bulletins based on material collected in the Ross Sea during the early New Zealand work there, and especially from extensive dredging and trawling programmes carried out from H.M.N.Z.S. Endeavour in 1958-59 and 1959-60, under the general heading " The Fauna of the Ross Sea ". The results of biological work stemming from U.S.A.R.P. activities are now appearing in an Antarctic Research Series. Two bulletins on Polychaeta (Hartman, 1964, 1966), and others on Cirripedia (Newman and Ross, 1971), Ascidiacea (Kott, 1969) and Antarctica-Subantarctic Marine Algae (Papenfuss, 1964b) have been published. Soviet work on the benthos carried out from the Ob and other vessels has been published in a series of " Biological Reports of the Soviet Antarctic Expedition (1955-1958)"', four volumes of which have fortunately been translated into English. Shorter preliminary reports of Soviet work have appeared in " Soviet Antarctic Expedition Information Bulletins ", many of which have also appeared in English translation. Many of the papers relating to French Antarctic work have appeared (or have been reprinted) in a series of publications of " Expeditions Polaires Frangaises ". Japanese marine material was mostly collected from R.V. Umitaka Maru, and some of the reports are published in JARE Scientific Reports. British biological work is being published in a series under the title of " Scientific Reports of the British Antarctic

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Survey ”. Many results are, however, being published in the normal scientific literature, so that keeping in touch with the literature of the last few decades is a difficult task. The United States produces an “Antarctic Bibliography ”, issued first as index cards and later consolidated into bound volumes. One of the most useful general bibliographies of Antarctic and Subantarctic biology is that produced as a subject bibliography by Amaud, Arnaud and Hureau (1967) arranged in broad systematic sections. An invaluable bibliography of papers by Soviet workers has been published by Petrovskaya (1968).

IV. THEFAUNAOF ANTARCTICA Every major group of marine benthic animals seems to have been recorded from Antarctic waters, although the representation within these major groups may be uneven. The occurrence of higher Crustacea may be used to illustrate this point although i t will be demonstrated in considering many of the animal groups that follow. Benthic decapods are rare, brachyuran crabs not having been recorded, apart from a doubtful reference of Halicarcinw to the South Orkneys. Anomurans are represented by rare lithodid crabs at Scott Island and at South Georgia. Stomatopods are lacking completely. On the whole it is at about the level of Orders that occasional gaps appear in Antarctic checklists, although most of the noteworthy gaps are at the family level or slightly higher. Groups of animals which are well represented are those adapted to make use of the great summer bloom of phytoplankton. Many of these animals have thrived under Antarctic conditions, e.g. sponges, bryozoa, ascidians, gorgonian corals, hydroids, bivalves, cirripedes, sedentate polychaetes, ophiuroids and crinoids. Many of these are sedentary, anchored to the substrate, some are colonial. Especially in shallow water a surprising number, often the most common animals, practice either facultative or obligatory necrophagy (Arnaud, 1970). Some groups seem particularly well represented in Antarctic waters. Outstanding examples are siliceous sponges, pycnogonids and isopods. Some individual species occur in very high numbers, e.g. the nemertean Lineus corrugatus, the amphipods of the genus Orchomenella, small gastropods of the genera Subonoba and Ovirissoa, and the ophiuroid, Ophiacantha antarcticu. The collections of echinoderms from off Adelie Land from 0 to 60 m contained 1 100 specimens of Sterechinus neumayeri (85% of all the echinoids collected) and 736 specimens of Odontaster validus (87% of all the asteroids collected) (Amaud, 1964).

R. K. DELL

FIQ. 2. Typical distribution patterns of some wide-ranging invertebrates essentially confined to the Antarctic Region (data from Pawson, 1969b, Fell, Holtzinger and Sherraden, 1969, Squires, 1969, Kott, 1969b, Dell, 1969, Hedgpeth, 196913 and Dearborn and Rommel, 1969). 0 Sterechinw, neumayeri; OphiaCantha antarctics; A ffardineria anlarctica; A Pyura diawveryi; V Laternula elliptica; 0 Megalonyx mbusta; Promachacrinus lcerguelensw.

Of the 800 specimens of asteroids collected on the BANZAR Expedition, 412 belonged to Odontaster validus (Clark, 1962). Another obvious characteristicis the high percentage of forms which exhibit viviparity or brood protection in one form or another.

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FIG.3. Typical distribution patterns of some wide-ranging invertebrates which extend their ranges outside the Antarctia Region (data from Fell, Holtzinger and Sherraden, 1969, Squires, 1969, Edmonds, 1969, Dawson, 1969 and Dell, 1969). Ophiaoantha vivipara; 0 Fhbellum impeneum; Cfoljhgia margaritaceu capeiform&; 0 Lineua corrugatua; A Limop8k mam'onenaia.

Some groups appear to show the effects of radiative evolution with a large number of related forms adapted to different ecological niches. Good examples are the nototheniiform fishes and the littorinid, trichotropid and buccinid gastropods.

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Many Antarctic benthic animals have been recorded from a single station, or from a relatively restricted geographical area. It is impossible to decide if these species have a restricted distribution in fact, or if the species has not as yet been collected adequately. Some of the wide ranging species which may be considered as typical Antarctic forms are confined strictly to the Antarctic Region (Fig. 2). Other wide ranging species equally typical of the Antarctic biota extend their ranges into the Subantarctic or into southern South America. The ranges of some of those species taken from varied systematic groups are shown in Fig. 3. Detailed accounts of the main groups of animals follows. A. .Foraminifera The benthic Foraminifera of the Antarctic have been described and discussed by a long series of authors, almost in direct inverse proportion to their size. This is not surprising since the benthic forms are easily collected in bulk and can often be obtained from material which has not been primarily obtained for biological purposes, let alone for foraminiferal workers. Chapman’s paper (1916) on Foraminifera and Ostracoda obtained from the material obtained on sounding leads on the British Antarctic Expedition, 1907-09, is a good example. Work on the Foraminifera in general has also been well financed because of the obvious economic value in stratigraphy, and hence the prime importance of the group to such economic ventures as oil prospecting. Because they are usually the dominant organism present in sea bottom cores their systematics and distribution have been carefully studied. These factors have not yet affected the study of the Antarctic forms markedly but it has meant that the literature on the group is well organized and many of the basic systematic problems have already been thoroughly dealt with. Early work on the group in the Antarctic was mainly concerned with systematics and distribution, and indeed a good deal probably remains to be done along these lines of investigation. New species are still being described even from such relatively well worked areas as the Ross Sea (Kennett, 1967). The fist Antarctic species were recorded by Ehrenberg (1844) from material collected on the voyage of the Erebw and Terror. A summary of this rather sketchily identified material is given by Heron-Allen and Earland (1922, p. 28). Major reports from Antarctic expeditions have been contributed by Brady (1884), two of the Challenger deep-water stations being south of the Antarctic Circle; Faure-Premiet (1911, 1913, 1914) from the two French Expeditions ;Heron-Allen and Earland (1922) from Terra Nova

LNTAlZUTIU BENTHOS

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material; Pearcey (1914)from the Scottish National Antarctic Expedition; Chapman (1916a, b) from the British Antarctic Expedition 190709 ; Wiesner (1931) from the German South Polar Expedition ; HeronAllen and Earland (1932) and Earland (1936) from the material collected by the Discovery Investigations ;Chapman and Parr (1937) from the Australasian Antarctic Expedition ; Cushman (1945) from the U.S. Antarctic Service Expedition and Parr (1950) from the B.A.N.Z.A.R. Expedition. Warthin (1934) recorded some material from 1 600 ft in the Bay of Whales, Ross Sea, and Crespin (1960) studied Foraminifera from terraces in the Vestfold Hills and reviewed some previous work. Some of these earlier reports went beyond questions of identification, classification and distribution. A much stronger ecological basis and a rather different outlook has been apparent in more recent work, obviously influenced by the trends of research in other areas. The workers responsible have been able to escape very largely from the qualitative approach of the earlier works (essential though this W ~ Ba t the time) and develop a much more quantitative approach. Uchio (1960) studied the benthonic Foraminifera from ten samples from Lutzow-Holm Bay (38'E). He recognized three assemblages based on depth 1. From 350 to 850 m with the characteristic species, Angulogerina angulosa Cushman, Epistominelh exigua (Brady) and Ehrenbergina glubra Heron-Allen and Earland. 2. Prom 850 to 2000m. An assemblage of Bulimina aculeata Orbigny with a dominance of Eponides weddellemis Earland. 3. Deeper than 2 000 m. Assemblages of Eponides weddellensis and Epistominellu exigua. The two species Haplophragmoides bradyi (Robertson) and Bulimina rostrata Brady appeared to be restricted to this zone. Saidova (1961) demonstrated an increase in Foraminifera down to about 400m. Abundant calcareous species occurred down to about 4 000 m. Species groups occurred at 150 to 500, 1 200 to 2 800, and at 3 500 to 5 000 m respectively. A major contribution came from McKnight (1962) who reviewed previous work on Foraminifera in the Antarctic and presented very full quantitative data based on 28 surface core samples. From an analysis of his results he could find no correlation between distribution and depth, temperature, salinity, or mean grain size. Organic carbon seemed a possible controlling mechanism especially for arenaceous species. I n some instances the spread of grain size in the sediments also appeared to have some effect. McKnight postulated a bottom current carrying a

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high arenaceous and a low calcareous foraminifera1content passing over the stations in which he had found high arenaceous contents, in order to explain the distribution of foraminifera he had observed in the Ross Sea. At the same time this current would have swept most planktonic species out of the area. Pflum (1963) studied 10 surface core samples from the Ross Sea. His results largely agreed with those of McKnight. Blanc-Vernet ( 1965) described the distribution of Foraminifera from nine samples from off Adelie Land, in depths from 10 to 270 m. These samples fell into two groups, a shallow water fauna from 10 to 40 m and a deeper fauna from 180 to 270 m. A larger number of families was represented in the deeper series. The family Trochamminidae was much commoner in the shallower series, the genus Trocbmmina (except for F. globigeriniformis) being largely confined to depths less than 100 m. The families Textulariidae, Cassidulinidae and Buliminidae seemed present in both series roughly in the same percentage. The families Lagenidae, Polymorphinidae, Miliolidae and Silicinidae, well represented in the deeper series were absent from the shallower group. Bandy and Echols (1964) analysed all the data previously collected on the Antarctic forms, including that presented by Uchio (1960) and McKnight (1962). A careful examination of these existing records gave the following zones for zonation of Antarctic benthic Foraminifera. 1. 200 (&150) m. aculeata group. 2. 500 (f 160) m. pusilla Brady group. 3. 1 000 (f200) m. 4. 2 000 (+200) m. 5. 2 400 (f600) m.

Adercotryma glomerata (Brady)-Bulimina Cibicides wuellerstorfi (Schwagar)-Cyclammina Cyclammina orbicularis Brady group. Astrorhixa crassatina Brady group. Bulimina rostrata group.

Bandy and Echols present several useful tables giving bathymetric ranges for selected index species. They also showed that some Antarctic species occur in different depths from those known for the same species in other areas (heterobathyl species). For example Laticarinina pauperata (Parker and Jones) occurs in the deep cold waters of the Antarctic and in shallower warm waters in the Gulf of Mexico. A major contribution to our knowledge of the ecology and distribution of Antarctic Foraminifera is Kennett’s (1968) study of Ross Sea species. Based on 48 newly collected bottom stations and 60 earlier samples spread more or less over the whole extent of the Ross Sea it gave a wider geographical and bathymetric coverage of a restricted area than had been available in Antarctic waters before. A total of 102 genera and 210 species were identified, and bathymetric distribu-

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tion and abundance for each species was recorded. Kennett found that his faunas fell into two separate and completely contrasting groups. 1. A calcareous fauna, with abundant calcareous Foraminifera, moderately abundant Ostracoda, Bryozoa, small Mollusca, etc. but with relatively few arenaceous Foraminifera, generally a high number of foraminiferal species present. 2. A dominantly non-calcareous fauna, with arenaceous Foraminifera, diatoms and siliceous sponge spicules. This group of faunas with more than 85% of the benthic faunal constituents consisting of arenaceous Foraminifera was defined by Kennett as arenaceous faunas. Arenaceous Foraminifera build their tests by cementing various materials such as sand grains or sponge spicules with a predominantly ferruginous secretion. Only a relatively small number of species is usually present. Most of the calcareous faunas occurred in depths shallower than 550 m, while all the arenaceous faunas were found deeper than 430 m. Kennett stresses that approximately the same number of arenaceous species occur in both calcareous and arenaceous faunas, and with some exceptions they are essentially the same species. The arenaceous faunas have much greater numbers of individuals. Arenaceous species characteristic of the calcareous fauna are Brachysiphon sp., and Ammodiscus cf. anguillae Hoglund. The more characteristic species in the arenaceous fauna include : Rhizammina indivisa Brady, Bathysiphon Jiliformis Sars, Pelosina bicaudata (Parr), CJlomospira charoides (Jones & Parker), R e o p h x distans Brady, R. spiculifer Brady, Adercotryma glomerata (Brady), Verneuilina minuta Wiesner and Karreriella pusilla Parr. There have been many attempts to determine the reasons for the level a t which arenaceous species become dominant, at whatever depth the phenomenon takes place. The general theory has been that there is a solution boundary beyond which at least thin-shelled calcareous foraminiferal tests are dissolved. General studies on this problem have indicated that the solubility of calcium carbonate increases with increasing salinity and with pressure. However it also appears that different species differ in the ease with which the test dissolves. It has been shown that in Antarctic waters generally quite abundant calcareous foraminiferal faunas do exist down to at least 4 000 m. (Saidova, 1961 ; Bandy and Echols, 1964). Kennett (1968, p. 34) believes that solution of calcium carbonate occurs at shallower depths in the Ross Sea because the water below about 550 m is highly unsaturated for a number of reasons. The water is at very low temperature even for Antarctic sea water ( O O C to -2°C) at a very high salinity (34.75 to 35.00%). Such cold water would allow

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an increase in the amount of dissolved carbon dioxide, which is readily available in the Ross Sea since sunlight is lacking for about half the year, and since many animals live permanently away from light under the Ross Sea shelf. These are of course factors which can be checked, and the work planned for examining the water beneath the Ross Ice Shelf will add some firm knowledge in this respect. On the face of it, however, it seems difficult to see that such a great difference in depth should exist between the “ calcium solution ” layer at about 530 m in the Ross Sea, and at 4 000 m in the Antarctic waters just outside the Ross Sea area. If this factor is to work on the tests of Foraminifera, it should also work to obliterate the shells of Mollusca. It may very well do this in the course of time but dead shells occur below 500 m in the Ross Sea in numbers. The shells of live Mollusca from deeper water contain little calcium carbonate, but that is rather a different matter. The cores studied by McKnight (1962) from the Ross Sea showed an increase in the percentage of calcareous benthic specimens present from top to bottom in his cores. He postulated two possible reasons for this. The first supposed that arenaceous forms had not yet entered the Ross Sea in strength and had gradually done so over the time the sediments in the cores were being deposited. The second required a change in water masses because of climatic change. Kennett (1968) believed that the second explanation fitted the facts of the situation better. An increase in the percentage of calcareous forms would represent a warmer period with the calcium-solution boundary lowered correspondingly. As Kennett (1968, p. 35) suggested, “A study of the distribution of calcareous and arenaceous foraminifera1 assemblages in long cores from the Ross Sea may provide evidence of the climatic history of the area ”. From his analysis of bathymetric ranges for Foraminifera from his own samples, and from those recorded by McKnight (1962) and Pflum (1963) in the Ross Sea, ranging in depth from 90 to 3 570 m Kennett (1968) noted several abrupt changes with increasing depth. These main changes occurred a t about 270, 450 to 550 m, and at 1 300 and 2 200 m. The boundary a t 270 m was the upper depth limit for some 19 species. The relatively broad boundary between 450 and 550m seems to represent the calcium solution boundary and was the lower limit for practically every calcareous species. Ten arenaceous species reach their shallow depth boundary in this zone. Two species Hyperammina novaexealandiae Heron-Allen and Earland, and a species of Rhabdammina do extend into shallower depths but only occur in quantity from this zone down to about 2 200 m. At 1 300 m, the upper

ANTAEUYTIC BENTHOS

35

limits of the depth range of Cyclammina orbicularis and Cribrostomoides subglobosum (Sam), and the upper limit of abundance of Glomospira icharoides is reached, and Karreriella puailla, Reophax spiculifer and Hemisphaerammina depressa (Heron-Allen and Earland) reach their lower limits. At 2 200 m the upper depth limit of Ammomarginula ensis Wiesner, and the upper limits of abundance of Haplophragmoides rotulatum (Brady) are reached, while Hyperammina novaezealandia, a species of Rhabdammina, Reophax SUbfUSifOrmiS Earland, Bathysiphon discreta (Brady), Miliammina arenacea (Chapman) and Reophax subdentaliniformis Parr reach their lower limit. Boundaries were postulated at 475 m (McKnight)andat 515 and 1 134 m (Pflum), so that there appears to be a degree of agreement between these different workers. The number of species of Foraminifera recorded from different collections have been: 40 species from one Challenger Station a t 65'42'5 in 3 063 m (Brady, 1884) ; 216 species from the shelf and slope and 52 others in adjacent deep water basins from material collected by the German South Polar Expedition (analysis by Earland, 1935 based upon the report by Wiesner, 1931); 83 species from the Antarctic area especially the Weddell Sea (Pearcey, 1914) ; 342 species from the Australasian Antarctic Expedition (Chapman and Parr, 1937) ; 196 species and varieties from the B.A.N.Z.A.R. expedition (Parr, 1950). McKnight (1962) identified 133 species classified in 67 genera from 28 Antarctic cores, while Kennett (1968) identified 102 genera and 210 species from the Ross Sea. McKnight (1962) recorded that many of the 67 genera he recorded were believed to be confined to the Antarctic but no recent biogeographical account has come to notice. McKnight has recorded benthonic assemblages from the Ross Sea, the Weddell Sea, Queen Maud Land with a few records from the Palmer Peninsula. Other records are available for other areas, but some critical systematics w i l l surely be needed before comparisons can reasonably be made.

B. Porifera It has been claimed that the abundance of sponges in the Antarctic makes the present as much the Age of Sponges as was the Cretaceous (Burton, 1932). Practically every biologist who has worked in the Antarctic has commented on the number of sponges, their size and the part played in the fauna by the glassy sponges. The Erst scientific records were published by Carter (1872, 1875, 1877) who in 1872 described Tethya antarctica and Rossella antarctica from material collected in the Ross Sea by the Erebus and Terror, the

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genus Rossella being proposed for the second species. I n 1875 he discussed the genus Rossella, provided more information on R.antarctica and described further deep sea species from outside the Antarctic. I n spite of the difficulties inherent in work on the systematics of the group, reports on sponges have been produced by almost every Antarctic expedition, and the list of contributions is long indeed, the main authors being: Topsent (1901a, b, 1905, 1907a, b, 1908, 1910, 1912, 1913, 1915, 1916, 1917), Kirkpatrick (1902, 1907a, b, 1908), Jenkin (1908), Lendenfeld (1908), Schulze and Kirkpatrick (1910), Hentschel (1914), Dendy (1918, 1924), Brondsted (1928, 1931), and Tanita (1959). But two names are prominent amongst the students of the Antarctic sponges, the British zoologist Burton (1929, 1930, 1932, 1934, 1938) and the Soviet investigator Koltun (1964, 1969, 1970). Koltun (1964) recorded the sponges collected during the Soviet Antarctic expeditions mostly between 1955 and 1958, belonging to the Tetraxonida and Cornacuspongia. The sponges concerned come also from the South Orkneys, South Sandwich and Bouvet Islands, and South Georgia as well as from the Subantarctic islands of Marion, Crozet, Prince Edward, Kerguelen, Heard and Macquarie. In this paper Koltun diagnosed 230 species belonging to 98 genera, the two genera, CEudothenea and Bipcillopsis and 23 species being described as new. Koltun (1970) has recorded some 300 species of sponges from the Antarctic, the islands of the Scotia Arc, Bouvet, Marion, Crozet, Prince Edward, Kerguelen, Heard and Macquarie Islands. These are divided amongst the classes as follows : Calcispongiae Hyalospongiae Demospongiae

8 species ; - 26 species ; - 260 species.

Like the Arctic, the Antarctic sponge fauna shows a dearth of horny sponges. The families Geodiidae, Theneidae, Stellettidae and Tethyidae are either very poorly represented or are completely absent (Burton, 1932). The large glass sponges are, however, abundant, especially representatives of the family Rossellidae, species of which may grow to gigantic size, e.g. Scolymastra joubini Topsent, which may attain a height of 100 cm (Koltun, 1970). Antarctic sponges occur over wider bathymetric ranges than they do in other parts of the world. Koltun believes that this is related to the mixed bottom sediments which provide uniform bottom conditions over much of the shelf and continental slope. Because there is no

ANTARCTIC BENTHOS

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continental run-off oceanic waters extend right to the edge of the continent, allowing sponges from deeper water to occur in shallow water close inshore. The glass sponges are typically oceanic forms found only at depths greater than 100 m, but in the Antarctic they may be abundant near the coast even in water as shallow as 10m. The presence of bottom currents flowing from the continent outwards and downwards also tends to produce a uniform sponge fauna with no zonal distribution developed between 100 and 900 m. More than half the species recorded from the Antarctic (in the wide sense used by Koltun including also most of the Subantarctic) are endemic. Generic endemism is much less marked. Some 116 genera are known in the Antarctic. Of these only nine (Koltun, 1970) can be considered to be endemic, Scolymastra, Acanthorhabdus, Hoplakithara, Cercidochela, Meliidermu, Crellina, Bipocillopsis, Acanthoxa, and Cladothenea. Most of the Antarctic species of sponges belong to genera which are well represented in the seas of the world, e.g. Mycale, Asbestopluma, Myxilla, Tedania, Iophon, Hymedesmia, Isodictya, Anchinoe, Haliclona, Adocia, and Hymeniacidon. As in many other groups many sponges have a circum-Antarctic distribution. The commonest species in this group are : Rossella antarctica Carter, R . racovitzae Topsent, Scolymastra joubini, Cinachyra antarctica Carter, Tetilla leptodermu Sollas, Mycule tridens Hentschel, M . acerata Kirkpatrick, Asbestopluma belgicae Topsent, Iophon radiatus Topsent, I . spatulatus Kirkpatrick, Acanthorhabdus fragilis Burton, Cercidochela lankesteri Kirkpatrick, Tedania masaa Ridley and Dendy, T . oxeata Topsent, Axociella nidijcuta Kirkpatrick, Isodictya erinacea Topsent, Ectyodoryx ramilobosa (Topsent), Eurypon miniaceum Thiele and Microxina benedeni (Topsent), (Koltun, 1964). Koltun has shown that there are, however, marked differences between the faunas of East and West Antarctica. McMurdo Sound in the Ross Sea is the only area in Antarctica from which representatives of Stelletta, Geodinella, Jmpis, Penares, Hemiasterella, Rhabderemia, Chondropsis, and Dysidea have been collected (Burton, 1929). Other species, e.g. Hoplakithara dendyi Kirkpatrick, Plocumia gaussiana Hentschel, Clathria pauper Brondsted, Sphaerotylus schoenus Sollas, Dolichancanthu macrodon Hentschel, Desmucella vestibularis Wilson and Monoggringa longispinu von Lendenfeld have a wider distribution but are still confined to Emt Antarctica. Many fewer species are endemic to West Antarctica, e.g. Mycale macrochela Burton, M . tylotornota Koltun, Isodactyla toxiphila Burton, Myxilla australis Topsent, M . piatillaris Topsent, and Hymeniacidon

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torquata Topsent. Koltun (1970) does not believe that these differences between East and West Antarctica can be accounted for solely by our admittedly incomplete knowledge of the fauna. The closest relationships of the Antarctic sponges appear to be with the Falklands and southern South America. More than 50 species are found in both areas, whereas only 30 species are common to the Antarctic and Australasia. Abyssal sponges of the southern oceans are as yet hardly known. About 30 species have been recorded belonging t o such genera as Caulophacus, Malacosaccus, Holascus, Aubcalyx, Hyalonema, Asbestopluma and Cladorhim. One of the characteristic Antarctic sponge families is the Rossellidae. It is a family of glass sponges, some members of which grow to great size. Normally found below 100 m, members of this family are found commonly on the shelf. It is the abundance of these forms in comparatively shallow water that gives a unique character to the benthos of the Antarctic. Anyone who has sorted collections of Antarctic benthic animals either straight from the trawls, or from bulk preserved material in museum or laboratory on the other side of the world, will know the long, unbelievably sharp, glassy spicules which almost in themselves certify the collection as Antarctic. Koltun (1969) has presented eight distribution maps showing patterns for selected Antarctic and Subantarctic sponges (Fig. 4). I n the family Rossellidae, the genus Rossella is almost completely confined to Antarctic and Subantarctic waters (the one exception being R. nodastrella Topsent, from off the Azores). Burton (1929) had reduced the Antarctic species of Rossella to four, R. antarcticu, R. racovitzae, R. nuda Topsent, and R. villosa Burton (a course with which Koltun concurs). All four of these species are circumpolar, along with the two other characteristic members of the subfamily Rossellinae, Scolymastra joubini and Anoxyculyx i j i m e Kirkpatrick. Scolymastra joubini reaches a height of 100 cm or more. The group of the Tetractinellida has 19 species in the Antarctic. The most widely distributed and most characteristic of these are: Monosyringa longispina (Lendenfeld), Tetilla leptoderma SoUas, Cinachyra antarcticu Carter, C . barbata Sollas, and Plakina trilopha Schulze. About 25 species of the Clavaxinellida occur in the Antarctic, mostly belonging to the genera ~atrunculia,St~lacordyla,Xuberites, Polymastia, Sphaerotylus, Axinetla and Rhizaxinella. This group includes the main group of bipolar sponges and the level of endemics is comparatively low (35%). About 50 species of the wide ranging group of Haplosclerida occur,

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mostly on the shelf. The two genera Haliclona (with 20 species) and Adocia (with seven species) are the best represented genera. The Poecillosclerida as might be expected, is as well represented in the Antarctic as it is elsewhere, with 124 Antarctic species grouped in 47 genera. Most of these are widely distributed genera, with strong Antarctic representation. Many are circumpolar in distribution and seem to be related to the faunas of the Falkland Islands and southern South America. Burton (1932, p. 369) brought together the available information on the breeding seasons of Antarctic sponges. Information was available for 46 species, and although the records were too incomplete to enable definite conclusions to be reached, the indications given lead to some tentative deductions. There does not seem to be any major common breeding season. Some species seem to be breeding in any particular month. It also appears that most species of Calcarea breed throughout the year. Burton believed that the Antarctic sponges showed to a marked degree a free-living habit, extremely rare amongst adult sponges elsewhere. Most of the evidence seems circumstantial but the arguments seem strong that some of the species considered by Burton are not normally attached to a substrate. Koltun (1968) has shown the degree to which the free siliceous spicules of sponges occur in bottom sediments. From a study of the upper horizons of sediment cores in the Indian Ocean sector of the Southern Ocean he was able to demonstrate that siliceous spicules were extremely common. On the continental shelf and slope of Antarctica and in the adjacent ocean bottoms Koltun found areas containing from 100 to 300 spicules/cm2. On the shelf itself some areas produced more than 300 spicules/cm2. I n these areas silica was found to make up from 50 to 70% of the actual sediment and in places the surface " looks like spicular felt 65 cm thick ". Koltun records such sediments off the Banzare Coast, in the Davis Sea, off Lars Christensen Coast, MacRobertson Land and Kronprins Olav Kyst. The main contributing sponge genera are Rosella, Tetilla and Cinachyra. A very similar type of formation occurs in parts of McMurdo Sound (Bullivant, 1967). Farther north from the Antarctic Continent Koltun found a steady fall off in the number of spicules, ranging between 10 to 100 spicules/cm2. I n the southern part of the Indian Ocean the general figure is less than 10/cm2,although this figure rises considerably around the Subantarctic Islands and around shallow water banks. Sponges are only extremely abundant in the Antarctic down to between 600 and 600 m, the limit being usually fairly abrupt. Around

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FIG.4. Distribution of speoies of sponges of the subfamily Rossellinae (data from Roeeella rawvitzae; Koltun, 1969). A Roeeek a&r&ca; 1 Roes& nuda; 0 Roeeella villoea; 0 Scolymastra joubini; A Anoxyculyx ijimae.

1 500 to 2 000 m on the continental slope they are very rare. Spicules however occur abundantly beyond this depth, and in places may be commoner than they are on the shelf. Bottom currents are undoubtedly responsible for the transfer and Koltun shows that suspended midwater spicules were collected at various levels. Thia study ahould make

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palaeontologists rather wary of using fossil spicules alone as palaeoecological evidence. Koltun (1968) was able to identify down to species many of the sponges contributing to the sediments in various areas of the Southern Ocean.

Bipolarity The sponges are one of the few groups in which bipolar species are still recognized. Koltun (1969) considered that ten species could be considered bipolar. Sphaerotylus schoenus Sollas, S. borealis Svareczevsky ( = S. antarcticw Kirkpatrick), Suberites montiniger Carter, Artemisina apollinis (Ridley and Dendy), Hymedesmia simillima Lundbeck and H . longurius Lundbeck are all species which occur in both the Arctic and Antarctic and do not extend far into adjacent waters. Plakina monolopha Schulze, P . triZopha, Esperiopsis villosa (Carter) and Desmacidon fruticosa (Montagu) occur in both hemispheres but rather in temperate or subtropical waters. Other species which could be considered bipolar are Stylocordyla borealis Loven, Amphilectus fucorum (Esper), Adocia flagellifer (Ridley and Dendy), Aplysilla sulphurea Schulze and Halisarca dujardini Johnston. There no longer seems any doubt that these Southern Hemisphere species are identical with the Northern Hemisphere species. Koltun (1969) however pointed out that zoogeographical conclusions should not be taken too far as yet, since the sponge fauna of tropical waters has still not been studied.

C. Coelenterata 1. Scleractinian corals

Antarctic and Subantarctic corals have usually been considered to belong to the group of " simple " or " deep sea " corals. The term " ahermatypic " (literally non-reef building) is much more accurate and has been used much more frequently over the last decade in contrast to " hermatypic " (the corals of the reef building type). Considering the few species involved, knowledge of the Antarctic Scleractinian corals has only slowly accumulated and as Squires (1969, p. 16) has indicated they " are as yet inadequately known ". However, the systematic problems which Squires mentions are problems concerning all living ahermatypic corals and are not confined to the Antarctic. Workers who have contributed especially to our knowledge of the

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Antarctic corals of this group have been Gardiner (1913, 1929, 1939), Wells (1958) and Squires (1961, 1962, 1969). Seven species are now recognized from the Antarctic (Squires, 1969), Fungiacyathus symmetricus (Pourtales), Gardineria lilliei Gardiner, G. antarctica Gardiner, Flabellum antarcticum (Gravier), F. impensum Squires, Balanophyllia chnous Squires, and Caryophyllia antarctica von Marenzeller. Of these Fungiacyathus symmetricus is a cosmopolitan deep-water species recorded from a few scattered localities within the limit of the Antarctic Convergence, and Balanophyllia chnous is known only from the Ross Sea. Two species, Flabellurn impensum and Caryophyllia antarctica extend north to southern South America, while the remaining four species are endemic. Five species, Gardineria lilliei, G. antarctica, Flabellurn antarctica, P. impensum and Caryophyllia antarctica appear to be circumpolar in distribution, although the records for some species are sparse. Squires (1969, p. 17) believes that the Antarctic fauna is rather clearly demarcated from neighbouring faunas. The evidence points to a migration route from South America to the Antarctic Peninsula which is obviously still available, and a possible more ancient route through the Macquarie Rise. Squires also pointed out that the indications of uneven distribution patterns for southern corals from " blind " dredging and trawling have been confirmed by underwater photography. When corals do occur, they may be present in great numbers, but such concentrations may be separated from one another by areas of very low coral density. As with members of other groups of animals, the depth ranges for Antarctic corals are wider than they are for similar species elsewhere. Squires (1962, p. 12) gave a table showing the ranges for the species known from the Ross Sea.

Caryophyllia antarctica Flabellurn impensum F . antarcticum Gardineria antarctica G. lilliei Balanophyllia chnous

46-600 m 46-2 260 m 53-591 m 46-603 m 95-360 m 355-457 m

2. Actiniaria This is a group upon which little recently published material is

available. Contributions based upon expedition material have come from Clubb (1902, 1908), Roule (1911) and Pax (1922a, 1926). The major worker in the Antarctic, as elsewhere, has been Carlgren

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(1903, 1914, 1927, 1928, 1930 and 1939). The last publication to discuss the composition and distribution of the Antarctic fauna as such seems to be Carlgren (1928). I n this paper he lists 31 species from the Antarctic. One of these, Halcampoides purpurea (Studer) is cosmopolitan. Five other species are found elsewhere, e.g. Edwardsia intermedia McMurrich, Choriactis laevis (Carlgren), Glyphoperidium bursa Roule, Hormosomu scotti Stephenson and Artemidactis victrix Stephenson. Edwardsia intermedia occurs on the Antarctic Peninsula and at South Georgia, Tierra del Fuego and off Southern Chile, while Choriactis Zaevis occurs on the South Shetlands and South Orkneys, the Burdwood Bank and Tierra del Fuego. These two species with restricted distribution in the Antarctic could perhaps be more properly considered Subantarctic species which have extended into the Antarctic through the Scotia Arc. The other three species mentioned had a wider distribution in the Antarctic but extended north to South Georgia. Carlgren was here not considering South Georgia as falling within the Antarctic region. Distributions of this type are well exemplified in other groups of animals. The following species appear to have a circumpolar distribution : Dactylanthus antarcticus (Clubb), Glyphoperidium bursa Roule, Hormosoma scotti, Stomphia selaginella (Stephenson), Artemidactis victrix and Tealianthus incertw Carlgren (Carlgren, 1928). Some 19 species appear to be confined to East Antarctica, and two to West Antarctica, apart from nine which are confined as far as is known to South Georgia. Two species seem so far to be known only from off Bouvet Island. Judging by the records available the fauna of East Antarctica would seem to have been rather more thoroughly collected than that from West Antarctica. Of the 31 species recorded by Carlgren (1928) from the Antarctic seven were known from depths from 0 to 200 m, seven spanned part of the range from 0 to 700 m, 12 occurred between 200 and 700 m and five were only known from depths greater than 1 0 0 0 m. However, many of the species concerned had only been recorded from one station and the bathymetric data generally seem rather sparse. Dayton et al. (1970) have published a series of delightful underwater photographs of Urticinopsis antarctica (Verrill) in McMurdo Sound, and described its feeding habits, especially its preying on the echinoid Sterechinus neumayri (Meissner)as well as its habit of capturing medusae. The above authors recorded Artemidactis victrix, Isotealia antarctica Carlgren (believed to be a synonym of Tealianthus incertus by Carlgren), Urticinopsis antarctica and Hormathia lacunifera (Stephenson) as very conspicuous in a zone between 15 and 33 m in McMurdo Sound.

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3. Antipatharia The Hexacoral group of Antipatharia has received but slight attention in Antarctic waters. The chief contributors have been Thomson (1908), Thomson and Rennet (1931), and Pasternak (1961). Thomson (1908) described a new species Bathypathes bijda from 71'22'5, 16'34'W. Thomson and Rennet (1931) recorded one species Euuntipathes plana (Cooper) from off Macquarie Island and Bathyplanes patula Brook from 64"34'S, in 3 109 m. Pasternak (1959) recorded the discovery of further specimens of the cosmopolitan antipatharian Bathypathes patula off the Antarctic continent in depths of 4 636 and 4 200 m. 4. Octocorallia

The subclass Octocorallia is divided into the three orders, Alcyonaria, Gorgonaria and Pennatularia. Molander (1929) contributed a major report on the whole subclass in his report on the collections of the Swedish Antarctic Expedition. Most other authors have been concerned with one or other of the orders. The Alcyonaria have been dealt with by Roule (1902, 1907, 1908), Hickson (1907), Kuekenthal (1906, 1912), Gravier (1913a, b, c, d), Thomson and Rennet (1931) and Deichmann (1945). Some of these authors mentioned above have also dealt with the Pennatularia but the following workers have been concerned primarily with this latter order : Jungersen (1907), Broch (1959) and Pasternak (1962, 1961). The Alcyonaria are not well represented in Antarctica, the only species recorded apparently being Alcyonium antarcticum Wright and Studer from East Antarctica (Molander, 1929), A . paessleri May from the Antarctic Peninsula, A. clavatum (Pfeffer) from South Georgia and the Falklands, and Conulariella antarctica Gravier from the Antarctic continent and from South Georgia. Alcyonium antarcticum is also widely distributed in the Subantarctic and A . paessleri has also been recorded from Tierra del Fuego and from off South Africa. Eunephthya armata is known only from East Antarctica. The Gorgonaria are quite strongly represented but the recorded distribution patterns seem so patchy that little in the nature of zoogeographical conclusions can be drawn from the group. A few species are known from both East and West Antarctica, e.g. Primnoella antarctica Kukenthal and Thouarella variabilis Wright and Studer, a few are confined to West Antarctica and the Antarctic Peninsula, perhaps also extending to South Georgia and the Magellan region. The general

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composition of the fauna is as follows (number of species in parenthesis) : Pachyclavularia (2), Caligorgia (3), Primnoella (6), Lycurus (2), Thouarella (5), Ceratoisis ( l ) ,Primnoisis (6), Mopsea (2), Echinisis ( l ) , Callozostron ( l ) , Ascolepsis (2) and Leptogorgia (1) (Molander, 1929 ; Thomson and Rennet, 1931). The difficult genus of pennatularians, Umbellula, has recently been revised by Broch (1959). Species of Urnbellula occur in the ocean basins of the world. Apart from a single record of U . durissima K6Mcker from 3 185 m in the Antarctic, Broch believed that the sole Antarctic species is U . lindahli Kallicker. This latter form known from the Atlantic, Indian and Pacific Oceans in depths from 310 to 5 300 m, has been recorded from Antarctic waters in depths from 77 to 3 560 m. It is almost certainly circum-Antarctic in distribution. Pasternak (1 962) basing his conclusions largely on the material collected by the Soviet Antarctic expeditions disagreed with Broch’s conclusions, and demonstrated that Umbellula magniJEora can be satisfactorily separated from U.lindahli. Both species are widely distributed in other areas as is a third species recorded from the Antarctic by Pasternak, Umbellula thomsoni . The only other known pennatularim seems to be Kophobelemnon paucifirum described by Molander from off the Antarctic Peninsula. 6. Hydroidea

Naumov and Stepaniants (1962) have given a short general account of the Antarctic hydroid fauna and its affinities as an introduction to the systematic study of the material collected by Soviet Antarctic Expeditions. This is in fact one of the few general accounts of the Antarctic members of the group although systematic accounts have been contributed by Browne (1902), Hartlaub (1904), Jaderholm (1904, 1905, 1926), Billard (1906, 1914), Hickson and Gravely (1907), Ritchie (1907, 1909, 1913), Vanhoffen (1911), Totton (1930), Briggs (1939), Broch (1948), Manton (1940) and Naumov and Stepaniants (1958, 1962). The last named authors (1962) estimate that about 178 species of Thecaphora have been recorded from Antarctic waters, although critical work may reduce this number. Although a large number of species have been recorded, hydroids do not make up a great quantity of bottom material. There are a high percentage of endemic forms, the genera Abietinella, Billardia, Oswaldella and Stegella being confined to the Antarctic and Subantarctic zones. Naumov and Stepaniants (1962) cannot make a clear distinction between the hydroid fauna of the Subantarctic and the

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Antarctic zones and, in considering endemism, they referred to both as the one zoogeographical area. The genera Plumularia (with 18 species), Campanularia (with 15 species) and Sertularella (with 40 species) are extremely well represented although the genera Sertubria and Thuiaria which are the predominant genera in the corresponding zones of the Northern Hemisphere are poorly represented in the Antarctic. Some species appear to be circumpolar in distribution and confined to the Antarctic in the restricted sense, e.g. Opercularella belgicae (Hartlaub), Stegella grandis (Hickson and Gravely),Sertularella glacialis Jiiderholm, Oswaldella bifurm (Hartlaub), and 0. billardi Briggs. Hydroids often have a wide distribution pattern and some cosmopolitan species extend into Antarctic waters, e.g. Sertularella polyzonias (Linnaeus), S. tricuspidata (Alder), Pilellum serpens (Hassal), and Lafoea fruticosa (Sars). I n parts of the Ross Sea hydroids appear to be well developed and large clumps of various species are encountered. These species forming large clumps include Halecium arboreum Allman, Sertularella spiralis Hickson and Gravely, 8.plectilis Hickson and Gravely, Dictyocludium ficscum Hickson and Gravely and Plumularia glacialis Hickson and Gravely (Hickson and Gravely, 1907). A small mud-dwelling, solitary hydroid Boreohydra simplex Westblad was described from off the Scandinavian Atlantic coasts and subsequently recorded from off Iceland and the English coast. It then turned up from mud samples collected off South Georgia (Westblad, 1952). This distribution pattern cannot be given too much weight until it has been searched for more carefully in intervening localities. 6. Stylasterina

The Stylasterina, one of the two orders of hydrozoan corals, form a rather obvious component of Antarctic benthos. They have been studied by Marenzeller (1903), Broch (1951), Boschma (1966), and Eguchi (1964). A recent summary on the distribution and relationships of the Antarctic fauna has been given by Boschma and Lowe (1969). These two authors find that a distinctive fauna inhabits the AntarcticSubantarctic area. Unfortunately they take the northern limits of the Subantarctic considerably farther to the north than would most biogeographers, including the coastal waters of New Zealand, and even considering the Kermadec Islands, " in the border region of the Subantarctic". The Kermadec Group is essentially an outlier of the tropical Indo-Pacific fauna, with outliers of the tropical reef corals. When therefore they speak of 15 of the 19 Antarctic-Subantarctic

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species of Stylasterina as being strictly endemic, they are including Challenger Station 320 at 37’17’5 as being in the area. This makes comparative analysis difficult. Based upon Boschma and Lowe’s distribution maps and text, 12 species of Stylasterina have been recorded from the Antarctic in the sense used throughout this present work. These are : Errina antarctica (Gray), E . gracilis von Marenzeller, E . laterorifa Eguchi, E . aspera Gray, E . Jissurata Gray, E . labiata Moseley, and an undescribed species, Allopora eguchii Boschma, and an undescribed species, Compora paucisepta Broch, Sporadopora dichotoma Mosely, and S. mortenseni Broch. Of these, five appear to be endemic to the Antarctic (Errinu laterorifa, E . fissurata, and an undeacribed species, Allopora eguchii, and an undescribed species). Two other species are known only elsewhere from southern South America, one only from off Tristan da Cunha, one only from New Zealand, one ranges also from South America to the Indian Ocean, one extends to the subtropics, and one has a wide distribution even reaching the Mediterranean. Within the Antarctic, six species are known from both East and West Antarctica (although with some the stations from which they have been recorded are sparse), four are known from the Scotia Arc and the Antarctic Peninsula alone, two are as yet recorded only from East Antarctica. These corals have very considerable bathymetric ranges, but most occur between 200 and 1 300 m, although Errina antarctica has been collected from only 3&m.

D. Turbellaria Westblad (1952) gave a useful summary of the history of work on Turbellaria in the Antarctic. Material was collected by the Belgica, the two French Antarctic Expeditions, the Scottish National Antarctic and the German South Polar Expeditions. Contributions on the Turbellaria from these expeditions have come from Boehmig (1908, 1914), Hallez (1905, 1906, 1911, 1913), Gemmill and Leiper (1907), Bock (1931) and Reisinger (1926). Westblad (1952) described the collections obtained by the Swedish Antarctic Expedition except for the Kalyptorhynchia, which were worked on by Karling (1952). Taking all the Turbellaria together, 21 species have been recorded from South Georgia, seven of which appear to be endemic, 11 are found also in the Magellanic Region (and in some cases have a wider distribution) and three also reach West Antarctica. This is probably not really indicative that South Georgia has a much more numerous Turbellarian fauna than other parts of the Antarctic, but just that the collecting effort in South Georgia has been greater. Two other species have been

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recorded from the Antarctic Peninsula and one from the South Orkneys. About 11 species seem to have been recorded from East Antarctica. Only a few species have had ranges recorded embracing both East and West Antarctica, e.g. Rimicola glacialis Bahmig, although a number have extensive distributions from the Magellan Region and to varying degrees down the Scotia Arc and also from Kerguelen, e.g. Stylochoides albus Hallez, Procerodm ohlini (Bergendel) and P. wandeli Hallez. Westblad (1952) believes that the scattered occurrences of turbellarians on Kerguelen Island and the islands of the Scotia Arc seem to demonstrate that the Antarctic Continent was formerly much wider in extent. Since these littoral species have no pelagic larvae, their dispersal by sea currents is inconceivable, “ so that the scattered occurrence of a Turbellarian species must be interpreted as a remainder of an ancient continuous distribution ”. Perhaps this is a rather broad conclusion to be based upon such evidence, especially in face of much contrary geological evidence.

E. Nematodu The first study on Antarctic free living nematodes seems to be that of von Linstow (1892) who recorded a few species from South Georgia. Cobb (1914) described two new genera and 25 new species from the Ross Sea from material collected on the Shackleton Expedition. A further collection from the Ross Sea was described by Allgen (1929). The large fauna obtained at Gauss Station by the German South Polar expedition was described by Steiner (1931). Mawson (1956, 1958) described material from East Antarctica collected by the B.A.N.Z.A.R. Expedition. A major advance in our knowledge of Antarctic nematodes has come with the publication of Allgen’s (1959) massive work dealing with the material sorted out from preserved bottom samples obtained mainly by the Swedish Antarctic Expedition. Based on some 6 000 specimens mostly from the Magellan Region, the Falkland Islands, South Georgia and the Antarctic Peninsula, Allgen recorded 343 species classified in 92 genera (13 of the genera and 200 of the species being described as new). Many of these were from the Magellan Region and from the Falklands. The fauna recorded from South Georgia comprised 143 species, of which 20% were common to southern South America, 49% were common to the Falklands and 17% common t o the Antarctic Peninsula. Nematodes are, however, wide ranging animals and 56 of the species now known from South Georgia also occur on the Atlantic European coasts. Some 21 species also occurred in Australia and 20 have been recorded also from Campbell Island. No records were known to Allgen from Kerguelen.

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No nematodes had previously been recorded from the Antarctic Peninsula. Allgen recorded 45 species, 24 of them also known from South Georgia and 25 from the Falklands, 10 from other localities in the Southern Hemisphere and 11 from the Atlantic coasts of Europe. No detailed comparisons have as yet been made between the nematodes of East and West Antarctica. Mawson (1956) recorded 36 species from East Antarctica, of which 27 species and one genus were described as new. I n a further paper Mawson (1958) recorded another 24 species including some from Australasian Antarctic Expedition material, 10 of the species being described as new.

F . Nemertea Nemerteans (or ribbon worms) are not well documented for the Antarctic. For proper systematic work well relaxed specimens, specially collected and carefully preserved are required. Even in trawls and dredges specimens often fragment before they reach the biologist. In the " heroic " age of biological collecting it was often impossible to give this group the patience and special attention they require (even if some biologists still doubt if they deserve it). One species above all others has been brought to the attention of practically every expedition that has worked in Antarctic waters, Lineus corrugatus McIntosh. Because it is abundant and widely distributed with a marked necrophagous habit, it has been commonly caught in baited traps and on fishing lines. Joubin (1905) redescribed this species under the name Cerebratulus charcoti Joubin, and described and figured a large hook baited with seal meat found in the interior of one preserved specimen. Arnaud (1970, p. 260) recorded that 130 individuals were taken by traps in Adelie Land, 39 individuals in one single trap at once and 27 new individuals in the same trap 24 h later. Arnaud also records one individual whose body had split in three places through ingesting a piece of meat weighing 56 g and another distended by a piece of meat weighing 61 g and measuring 9 x 3 x 1.5 cm, this in a species normally about 120 cm long but only 2 cm in diameter. An underwater photograph taken off Ross Island and published by Peckham (1964) gives some idea of the abundance of this species. Dawson (1969, p. 20) lists 29 benthic species from the Antarctic (in the sense it is used in the present publication). This includes seven species found in South Georgia (six of them endemic to South Georgia, one found also in the Falklands). Several species are known to have a circumpolar distribution around the Continent, e.g. Linew corrugatus, L. longijissus (Hubrecht),Antarctonemertes validum Burger, Baseodiscus

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antarcticus Baylis, Amphiporus spinosus Burger, and A . marioni Hubrecht . At our present stage of knowledge it may well be premature to discuss the relationships of the Antarctic fauna, since ranges in the Southern Ocean are obviously poorly known. There is obviously a strong tendency for the common Antarctic species to have wide geographical ranges, extending to the Falklands, Kerguelen and often to other Subantarctic Islands such as Macquarie Island. One species which could well be the basis for an individual study is Lineus corrugatus. Two cases of brooding in Antarctic nemerteans described by Joubin (1914) are noted in more detail in the section on egg brooding. G. Echinoderida Species of the rather poorly known group Echinoderida have been described from the Antarctic. Zelinka (1913) described Echinoderes ehlersi and Campyloderes vanhoeffeni from material collected by the German South Polar expedition. Lang (1949) described three new species, Echinoderes pilosa, Pycnophyes odhneri, and P . sculptus from South Georgia from material collected by the Swedish Antarctic Expedition.

H. Polycheta Hartman (1964, 1967) presented very useful summaries of the history of investigations into Antarctic polychaetes. The first benthic Antarctic species were collected by the British expedition under Sir James Clark Ross in the Erebus and Terror in 1841, and described by Baird (1865, 1870). McIntosh (1885) described some 62 species taken by the Challenger off the Queen Mary Coast of Antarctica. The report on the polychaetes collected by the Belgica in 1897-99 was not written up till much later by Fauvel (1936). Practically every expedition to visit Antarctica collected quantities of polychaete worms and most of the expedition reports have contained contributions on the group. Ehlers (1913) wrote up the polychaetes from the German deep sea expedition in the Valdivia, Willey (1902) the results from the Southern Cross and Ehlers (1913) again the material collected on the German South Polar expedition in the Gauss. The results of the Swedish Antarctic Expedition appeared in a series of papers by various authors from 1911 to 1953. Ehlers (1912) again was responsible for the results of the British National Expedition in the Discovery.

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Ramsay (1914) wrote up the Nereidae and Pixell (1913) the serpuliform annelids of the Scottish National expedition. Gravier (1906a, b, c, 1907a, b, 1911a, b) wrote up the polychaetes from the f i s t and second Antarctic expeditions. Benham (1927) dealt with the polychaetes of the B.A.N.Z.A.R. expedition and (1921) those from the Australian National expedition. The results of the Norwegian Antarctic expedition were written by Augener (1932a, b). The benthic material collected by the vessels of the Discovery Investigation was described by Monro (1930, 1936), the species of Spirorbis much more recently by Harris (1969). Results of the more recent collections have been contributed by Fauvel (1951), Hartman (1952), Ushakov (1957), Levenstein (1964), Knox (1962). Hartman (1964, 1966) has published two volumes which aim at bringing together all the previous published records, giving brief diagnoses of each species, and figures of many. They will serve as a magnificent base from which the collections amassed in the last 20 years may be attacked. Hartman (1967b) produced a volume based on material collected by the Eltanin and the Staten Island, mainly from the Antarctic. The families best represented in the Antarctic fauna are: Polynoidae, Syllidae, Terebellidae, Maldanidae, Sabellidae, Serpulidae, Spionidae, Flabelligeridae, Ampharetidae and Opheliidae (Hartman, 1966). Several families which are well represented in warmer seas have a poor representation in Antarctic waters. These include the Eunicidae, Amphinomidae, Sabellariidae and Pectinariidae (Hartman, 1966). The 457 species of polychaetes reported by Hartman (1966, p. 140) from south of 50"s include five parasitic, 212 errantiate and at least 240 sedentary species. Of these the five parasitic species, 46 species of the Errantia and 59 species of Sedentaria, a total of 110 species, are known from only a single record. A group including the following species is known only from depths of 1 000 m or more : Paronuphis abyssorum (Chamberlin),P . benthaliana (McIntosh), Nothria armandi McIntosh, Onuphis paucibranchis (Ehlers), Myzostomum compressum von Graff, M . coronatum von Graff, Brada gravieri McIntosh, Fauveliopsis challengeriae McIntosh, Ilyphugus coronatus Monro, I . wyvillei (McIntosh), !Pherusa sarsi (McIntosh), Ammotrypane nematoides Ehlers, Kesum abyssorum Monro, Grubianella antarctica McIntosh, Melinna buski McIntosh, Ampharetides vanhoefleni Ehlers, Potamethus scotiae (Pixell) and Apomatus brownii Pixell. Of the Antarctic and Subantarctic polychaetes listed by Hartman (1966) less than 10% are cosmopolitan species, or those known from

52

R. K. DELL

widely scattered localities. This figure includes the pelagic forms, which are largely cosmopolitan. As with many other Antarctic groups of animals some species of polychaetes prove to have very wide depth ranges. Examples of some of the most marked are : Barrukia cristata (Willey) 3.5-800 m Eucranta mollis (McIntosh) 40-900 m Harmothiie crosetensis (McIntosh) 187-2 926 m Notomustus latericeus Sars 0-1 777 m Isocirrus yungi Gravier 93-1 080 m Amage sculpta Ehlers 244-1 080 m Anobothrus patagonicus (Kinberg) 8-3 397 m Neosabellides elongatus (Ehlers) 97-1 000 m Eunoe abyssorum McIntosh 83-4 755 m Leaena antarctica McIntosh 13-3 612 m. Some Antarctic polychaetes grow to a very large size for the group. Hartman (1966, p. 154) listed 14 species which reach between 150 and 300 mm, and one, Ophioglycera ezimia (Ehlers) reaches a length of 760 mm. Knox (1962) listed 15 species of polychaetes collected at the Australian Antarctic base at Mawson, MacRobertson Land. The Antarctic and Subantarctic species of the families Phyllodocidae and Aphroditidae collected by the Soviet Antarctic expeditions were described by Ushakov (1962). This collection included 33 new species. The family Aphroditidae is better represented in the Antarctic than other polychaet families, many species occur massed in large numbers. Ushakov considered that about 50 species occurred in Antarctic (including Subantarctic) waters, with four endemic genera, Uorekia, Barrukia, Polyeunoa and Macelloides. The family includes such characteristically Antarctic species as : Laetmtonice producta Grube, Harmothiie spinosa Kinberg (possibly the most ubiquitous Antarctic polychaete), H . crosetensis (McIntosh),Hermadion magalhaensis Kinberg, and BarrzLkia cristata (Willey) . Members of the Phyllodocidae are much less important, but are represented by about 20 species. Almost all the species of these two families occurring south of 450-50°S are endemic to this area. As for so many other groups, the Magellan region appears to act as an area of faunal exchange between the temperate regions of the southern hemisphere and Antarctica. Ushakov provides descriptions of all the specimens collected by the Soviet expedition, and lists known ranges. Levenstein (1964) dealt with the families Terebellidae and Tricho-

53

ANTARCTIC BENTHOS

branchidae from the same collections, recording 18 species including two new species, Laena pseudobranchia and Thelepides venustus, and recorded Eupistella grubei (McIntosh) from the Antarctic for the first time. Most of the species recorded belonged to endemic antarcticsubantarctic forms, with three species showing subtropical affinities, while two were cosmopolitan. All the species collected were briefly diagnosed, and figured where necessary. Full distributional data were presented. The distributional data presented by Hartman (1964, 1966) in her two volumes on polychaetes have been analysed with an Antarctic basis. The following conclusions are based upon a certain amount of simplification but will serve to point some general conclusions. The limits of the Antarctic region are those defined in the present work including South Georgia. The total polychaete fauna for the area, excluding pelagic forms and those occurring only over 1 000 m, is in the neighbourhood of 228 species and subspecies. Of these 119 (52%) are endemic to the area. The finer distribution of these 228 forms within the Antarctic and the spread of some of them outside the Antarctic is rather complicated. Some 60 species are found in the Antarctic only in East Antarctica, 37 of these being endemic to the area, three are also rather widely distributed outside the Antarctic, two are found also in Kerguelen, one each also in Australia and New Zealand, while eight are shared only with the Magellan region, two are found also in the Magellan area and have a more or less cosmopolitan distribution outside the Antarctic-Subantarctic area, four are shared with the Magellan region and varied Subantarctic areas while two more are shared with the Magellan area and other parts of South America. These are probably only paper complications and additional collections will certainly fill some of the outstanding gaps. Six species are found around the shores of the Antarctic Continent (five endemic and one cosmopolitan species) while another four species extend to the Antarctic Peninsula. Another 11 are circumpolar but extend to South Georgia. Some 58 species occur around the continent and extend to varying degrees t o the north in the area of the Scotia Ridge. Six species are confined to the continent, another four reach the Antarctic Peninsula, 12 more reach South Georgia, 22 extend into the Magellan region, and another 18 extend beyond the Magellan region to the Subantarctic Islands. Within the area from the Bellingshausen Sea to the Magellan region a number of distributional patterns can be discerned. Some 25 species are found in the Antarctic only along the Antarctic Peninsula, although five of these also occur outside the Antarctic, four species seem to be A.X.B.-lO

8

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R. I(. DELL

endemic t o the South Sandwich Islands and one endemic to the South Orkneys. Two species occur in both the Antarctic Peninsula and the South Orkneys. Seventeen species extend from the Antarctic Peninsula as far as South Georgia of which eight are distributed also outside the Magellan area. A further nine species extend from the Antarctic Peninsula as far as the Magellan area (eight of them extending also elsewhere). South Georgia appears to have 16 endemic species with an additional 15 shared with the Magellan region, and a further seven species occurring also outside the Magellan area. This summary of the recorded distribution (simplified as i t is) is given to show that the distribution of benthic Antarctic animals does not by any means fit a neat pattern. Additional collections will undoubtedly eradicate some of the apparent anomalies but may well introduce others. The spread of collections through the Scotia Ridge are obviously too scattered as yet for detailed analysis. The collections made by the Eltanin (judging by the published results for the ascidians) will go far to fill the gaps. I n a general paper on the Antarctic polychaetes (1967) Hartman indicated that while 457 species had been recorded before 1965, nearly as many again had been obtained in subsequent collections. Deep water faunas have been taken in depths down to 3 714 m off South Georgia, the Drake Passage, the Scotia Sea, and off the South Sandwich Islands. The Bransfield Strait between the South Shetlands and the Antarctic Peninsula yielded more than 100 species,includingpopulations of the large Laetmonice producta (around 770 m) and the southernmost recorded Chaetopterus (73 m). Other species which were well represented were : Neosabellides elongatus (Ehlers), Pista spinifera (Ehlers), Polyeunoa laevis McIntosh (commensal on a hydrocoral), Phyllocomus crocea Grube (in 265 m), the viviparous Paronuphis antarctica (Monro) and Rhamphobrachium ehlersi Monro (between 220 and 240 m), Steblosoma antarctica Monro, Pista mirabilis McIntosh, P . corrientis McIntosh, P . spinifera (Ehlers) and Serpula narconensis Baird (reaching its southern limit here in 884 m). Collections from the South Shetland Islands, the South Orkneys, off the Antarctic Peninsula, the South Sandwich Islands and the Weddell Sea are apparently similarly rich. The new bathymetric data available, with obvious peaked distribution at certain depths will supply the basis for a much fuller analysis. I n Hartman’s ( 1 9 6 7 ~ )study of the polychaetes collected by the Eltanin (1962-66) and the Staten Island (1963), she identified 367 species from Chile, southern South America, the islands of the Scotia Arc, the Antarctic Peninsula and the Weddell and Bellingshausen Seas,

ANTARCTIC BENTHOS

56

a sign of the productivity and diversity of the area. I n the general section of this report Hartman presents a useful summary famiIy by family of the polychaetes from the area studied. The four pages of summary are so compactly presented that further compression would destroy any value. Hartman also gives station lists and a short general account of the polychaetes from each of 19 general areas. Harris (1969) has worked on the systematics of the serpulid genus Spirorbis in the South American sector of Antarctica and has discussed the biogeography of the group. Six species are now known from this sector of the Antarctic. Spirorbis digitus Harris and S. pixelli Harris occur off South Georgia, S . pixelli and S. indicus Sterzinger off the South Orkneys, 8. moerchi Levinsen off the Antarctic Peninsula and S. aggregatus Caullery and Mesnil and S. nordenskjoldi Ehlers from Petermann Island. Of these 8. nordemkjoldi is known also from East Antarctica and from Bouvet Island, as well as from the Magellan region. S. digitus and S. pixelli appear to be endemic to this area, and S. aggregatus occurs also at the Falklands and on the Patagonian shelf. But 8. indicus is known elsewhere from Suez while S. rnoerchi is recorded from the Gulf of Mexico and from the Bay of Naples. One would expect species of Spirorbis to have a wide distribution since they are easily carried by drifting algae and many forms live attached to algal fronds. However, one would expect such wide-ranging forms in the Southern Hemisphere to have a circum-Antarctic distribution. Evidently the distribution of Spirorbis is too sporadically known at present for useful biogeographical discussion. Two general points concerning the Antarctic polychaete fauna were raised by Gravier (1911~). Brooding of the eggs takes place in several different genera which do not show the habit in warmer seas. Examples are Eteone gainii Gravier and Flabelligera rnundata Gravier. Eteone gainii may be the same as Mystides notialis Ehlers (Hartman,

1964).

Gigantism amongst the polychaetes also crops up in different families, e.g. Trypanosyllis gigantea (McIntosh), Laetmtonice producta Grube and Flabelligera mundata.

I. Priapulida The priapulids have aroused great interest in the Antarctic because of the supposed evidence which they supply for the theory of bipolarity (ThBel, 1911). Expedition results on the group have been written by Shipley (1902), Thee1 (1911), Fischer (1921), Benham (1922), and Stephen (1941). Revisions of the group by Lang (1961) and more recently by Murina and Starobogatov (1961) and van der Land (1970)

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R . I(. DELL

have clarified the systematics and relationships of the Antarctic forms. There is apparently only one Antarctic species, P r i q u l u s tuberculatospinosw Baird which has been recorded from East Antarctica, the Antarctic Peninsula, the South Orkneys and South Georgia, as well as from New Zealand, Macquarie Island and southern South America. It is also known from scattered deep-water stations. Shipley (1902) recorded Priapulus caudatus Lamarck from two specimens washed ashore at Cape Adare at the entrance to the Ross Sea. One of these specimens has been examined by van der Land (1970) who found that rather surprisingly it agreed better with the northern P. caudatus than with P . tuberculatospinosus but preferred to base no conclusion upon this rather anomalous record. The example of bipolarity which the group has been supposed to show rather dissolves as a result of the recognition of P . caudatus as an essentially northern form and P. tuberculatospinosus as essentially southern (Lang, 1951) and the recognition of Priapulus as a widespread deep-water genus (Murina and Starobogatov, 1961; van der Land, 1970).

J . Sipuncub The main contributions to our knowledge of Antarctic sipunculid worms have been: ThBel (1911), Stephen (1941, 1948), Murina (1964) and Edmonds (1965, 1969). This is one of the difficult groups to classify, and also m e of the groups from which evidence of bipolarity has been taken. Only the two genera GolJingia and Phascolion have so far been recorded from the Antarctic, the commonest Antarctic species being : GolJingia margaritacea capsiformis (Baird), G. anderssoni (ThBel), G. mawsoni (Benham), G. ohlini (ThBel) G. nordenskjokli (ThBel), Phascolion strombi (Montagn). Probably all the species of Goljingia listed above are circumAntarctic in distribution. There is some indication (Murina, 1964) that some of the species thought to be strictly bipolar are in fact widely distributed.

K. Echiura Three species have been recorded from the Antarctic (Edmonds, 1969) ; Maxmulleria faex Selenka, Echiurus antarcticus Spengel and

ANTARUTIU BENTHOS

67

Haminqia arctica Koren and Danielssen. The latter two are northern species identified from the Antarctic (Stephen, 1941). The Antarctic records of Maxmulleria faex are based on one fragmentary and two complete specimens from the South Shetlands, that of Hamingia on a slightly damaged specimen from the same locality.

L. Brachiopoda The major contributions to the literature of Antarctic brachiopods have been Joubin (1901, 1914), Blochman (1906, 1912), Jackson (1912, 1918) and Thomson (1918). Foster (1969) has summarized our present knowledge of the composition of the Antarctic fauna, and the distribution of the species. Foster stressed that the Antarctic fauna is still incompletely sampled, and this is amply borne out by the sporadic distribution of many species shown on distribution maps. Sixteen species have been recorded from the Antarctic, which compares favourably with the numbers from other Southern Hemisphere land masses, e.g. southern Australia (17), New Zealand (lo), South Africa (16) and South America (11). Of the 16 Antarctic species, 11 appear to be endemic. One genus Compsothyris is endemic to the Antarctic. Foster considers that Aerothyris joubini (Blochman) and Compsothyris racovitzae (Joubin) are circumpolar in distribution. From his distribution maps it would appear likely that more extensive sampling will show that at least Crania lecointei Joubin, Amphithyris sp., and Aerothyrisfragilis (Smith) are also circumpolar, as well as the widespread deep-water species Pelagodiscus atlanticus (King). Some Antarctic brachiopods have wide bathymetric ranges, e.g. : Pelagodiscus atlanticus (366-5 530 m) Compsothyris racovitxae (329-2 580 m) Liothyrella antarctica (Blockman) (75-2 273 m) Liothyrella uva (Davidson) (0-2 150 m) Macandrevia diaminta Dall (2 580-4 066 m) Most of the similarities between the Antarctic and the recent faunas of New Zealand and Australia, and to some extent between South America and Antarctica, are probably due to a common pre-Tertiary fauna,. Present evidence suggests that deep-water forms such as Macandrevia and Liothyrella have migrated to Antarctica from South America, and the process may still be continuing. The genus Macandrevia (family Dallinidae) is found in the Southern Hemisphere only off South America and in the Antarctic. New Zealand has two genera, of the Antarctic fauna (Amphithyris and Liothyrella) amongst its fauna, and the Australian genus Magellania is quite close to the Antarctic

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R. K. DELL

Aerothyris. Otherwise there seems to be no obvious relationship with Australia, and none with South Africa. Allan’s more recent studies of the distribution of austral brachiopods (Allan, 1963) has borne out Thomson’s (1918) major conclusions. Genera which are common to New Zealand, Australia, South America and Antarctica belong to wide-ranging forms such as Lingula, Crania, Terebratulina and Liothyrella, which have little biogeographical significance. I n general therefore the brachiopods at present living in southern Australia, New Zealand and southern South America are largely characteristic of these areas, and represent the descendants of Tertiary species.

M. Bryozoa As with so many other groups the first truly Antarctic Bryozoa were obtained by the BeZgica (Waters, 1904), Southern Cross (Kirkpatrick, 1902), and the F r a n p i s (Calvet, 1909). Reports on subsequent expeditions added to our knowledge of Antarctic Bryozoa, the major accounts being Kluge (1914), Livingstone (1928) and Johnston and Angel (1940). A major contribution was the publication of Hasting’s work (1943) on the Discovery Collections followed by Borg (1944) on the material collected by the Swedish Antarctic Expedition. Vigeland (1952) reported on material collected by the Norwegian Antarctic Expedition. Dr Mary Rogick published a series of papers (1955-62) culminating in a review of the fauna (1965). Apart from a paper by Redier (1965) on material collected by the Belgian Antarctic Expedition, and a paper by Androsova (1968) on some of the Soviet collections, the enormous collections amassed in the last decade do not appear to have been worked on, and the review by Bullivant (1969) was based on the older published results. Bullivant’s (1969, p. 22) remark, “The Bryozoa are less well known than most other groups of the Antarctic benthos ” seems amply borne out by comments by both Hastings and Rogick. A point that is easily forgotten is that Hastings’ 200odd pages deal only with a small part of the fauna and that Borg (1944) dealt only with the Stenolaemata (= Cyclostomata) in his 276 pages. At the same time the group forms a not inconsiderable part of the Antarctic benthos in many areas (Bullivant, 1969), a point forcibly brought home to all biologists who have sorted bulk dredge hauls. Borg (1944, p. 14) has pointed out some of the difficulties in assessing earlier work on the Bryozoa and shown that many of the earlier identifications must be regarded as suspect (a stricture by no means confined to this group of animals). They are certainly a difficult group for a non-specialist to review, partly because they are numerous, partly

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59

because no specialist seems to have been able to discuss them in a way which makes them intelligible to a general biologist. Perhaps they are indeed a difficult group to present in an understandable fashion. Taking the Antarctic to cover the area so defined in the present work, Rogick (1965) gave a total of about 321 species (Bullivant gives a total of 310 species and subspecies.) Of these 179 are known exclusively from the Antarctic, giving about 58% as endemic. Rogick (1966, p. 403) lists the 179 endemic Antarctic species grouped as follows: Entoprocta ( l ) , Ctenostomata (2), Cyclostomata or Stenolaemata (18), Cheilostomata Anasca (fig), and Cheilostomata Ascophora (69). She divided the Antarctic into nine sections, each of approximately 40°, and analysed the 179 endemic species according to their distribution. The major conclusions were that the area around the Antarctic Peninsula yielded the greatest number of species with Kaiser Wilhelm, Victoria and Adelie Land sectors also showing good counts. As would be true of many other groups analysed in this fashion, what is really demonstrated is the degree of collecting effort that has been put into specific areas. This plus the fact that some 89 species proved to be known only from one sector seems further evidence that the Antarctio bryozoan fauna has not yet been well collected, Of the remaining 142 species found in the Antarctic but not confined to this area, Rogick states that they have been reported from warmer, more northerly waters about Australia, New Zealand, South Africa, South America and elsewhere. Bullivant (1969, p. 23) reported that a greater number of these (about 44 species) had also been recorded from the southern South AmericGFalkland Islands area than from the Australian-New Zealand region (about 8 species). Bullivant (1969) has raised the point that the cosmopolitan shallowwater species Bugula neritina (Linnaeus) apparently first recorded from the Antarctic by Redier (1965) may well have been accidentally introduced into Antarctic waters on the bottoms of ships, and has suggested that to follow its future possible spread would be a useful study. Hastings (1943) found the position of the Antarctic Convergence an important boundary in the distribution of the Antarctic group of Bryozoa. The great majority of the species she dealt with fell either into the Antarctic or the Subantarctic as split by the Antarctic Convergence with very few species occurring in both. On the basis of the Bryozoa, Hastings would unhesitatingly include Bouvet Island in the Antarctic, but would exclude Marion and Prince Edward Islands, the Crozets and Heard Island as Subantarctic. Thus Hastings’ Antarctic region is essentially the same as that accepted as such in the introduction to this work.

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R. K. DELL

Androsova (1968) listed all the Cyclostomata and Ctenostomata known from the Antarctic and Subantarctic and showed the distribution for each species. Of the total of 59 species recorded from the Antarctic, 22 were believed to be confined to the Antarctic, 20 were known from the Antarctic and Subantarctic regions, while 17 had a wider distribution.

N. Pycnogonida Although already known from elsewhere, the pycnogonids were amongst the very first Antarctic animals to be collected. James Eights (1836) described one from the South Shetlands and started a controversy that is perhaps not even yet settled. Sir James Clark Ross (1847, pp. 199, 201) described the finding of several specimens in 230 and 270 fm in the Ross Sea. Our knowledge of Antarctic pycnogonids has been slowly gained, the main contributions more or less in chronological order being: Hodgson (1902, 1907, 1908, 1927), Bouvier (l905,1906a,b, 1913), Calman (1915), Loman (1923), Gordon (1932, 1938, 1944), Stephensen (1947), Hedgpeth (1950), Utinomi (1959) and Fry and Hedgpeth (1969). Two recent reviews,Fry (1964)and Hedgpeth (1969a), give very useful summaries. Unfortunately for the present review the most recent systematic work (Fry and Hedgpeth, 1969) does not deal with the whole fauna. I n spite of the general title, ‘‘ The E’auna of the Ross Sea ”, this work is a complete review of the Antarctic pycnogonids. Only four families are treated in this first part, the Colossendeidae, Pycnogonidae, Endeidae and Ammotheidae. This first report therefore deals with 17 out of a total of 26 Antarctic genera. It is only these groups that are covered in the distribution maps presented by Hedgpeth (1969).

Fry (1964) gave a brief biogeographical summary for the pycnogonids known from the Antarctic. At that date 14 genera and approximately 100 species were known from the Antarctic. Of these 14 genera, two, Azcstropallene and Ammothea are found only on the shelf of the continent, while Pentanymphon, Decolopoda and Dodecolopoda are only found south of the Antarctic Convergence. This adds up to five endemic genera out of 14. Fry pointed out that this is a relatively high degree of generic endemism when other faunal areas are considered. There are only 36 genera of pycnogonids known and 75% of these occur together in the major ocean basins. More than 90% of the Antarctic pycnogonid species are endemic. Fry (1964) was a little doubtful if there was sufficient evidence to make the claim that pycnogonids were particularly common in the

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61

Antarctic. Hedgpeth (1969a), however, believed that in general there were somewhat higher proportions in the Antarctic. Gigantism amongst species and even some genera is a marked character of the Antarctic species. However, as Hedgpeth (1969)points out there are also many very small forms, some of the smallest pycnogonids known being endemic to the Antarctic. I n spite of the large number of species of pycnogonids recorded from the Antarctic most collections have had a preponderance of only a few species. Thus, in the Discovery collections examined by Gordon (1932), out of 1 800 specimens at least 1 200 belonged to the genus Nymphon and of these over three-quarters belonged to the two most common species, N . australis Hodgson and N . charcoti Bouvier. Calman (1915) reporting on the collections made by the Terra Nova had 240 specimens of Nymphon australis out of a total of about 600 specimens.

FIG.5. Two Antarctic pycnogonids. A. Ecleipaotkemmo apinom (Hodgson,) Ross See (redrawn after Hodgson). B. Auatrodecue glaciale Hodgson, McMurdo Sound (redrawn after Hodgson).

One of the burning questions that has plagued Antarctic pycnogonid systematics is the occurrence of three ten-legged and two twelvelegged species. Elsewhere the only divergence from the normal eightlegged condition is in two species in the American-AtIantic tropics. The first ten-legged pycnogonid was the one collected by Eights in the South Shetlands in 1830 (Eights, 1835),and thus the first truly Antarctic species known. Later naturalists considered this to be an error of observation. Antarctic expeditions after the turn of the century recollected Eights’ species and other ten-legged forms. The B.A.N.Z.A.R. Expedition obtained a giant twelve-legged form described by Calman and Gordon (1933) as Dodecolopoda mawsoni. A second specimen was figured by Fry and Hedgpeth (1969 Frontispiece). One major problem with these polymerous forms is that several of them are otherwise very

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R. I(. DELL

close to eight-legged species. It is possible that the extra segments, and extra pairs of legs may be caused by a doubling of chromosomes or by unstable development. It is obvious that in spite of all the work that has been done on Antarctic pycnogonids, collections are not yet good enough for the majority of species to give clear cut distribution patterns except for some few common species. A number of the better documented species such as Colossendeis robusta Hoek, C. lilliei Calman, C. scotti Calman, C. australis Hodgson, Pycnogonum gaini Bouvier, Austrodecus glaciale Hodgson, Dodecolopoda australis Eights, Ammothea carolinensis Leach, A . glacialis (Hodgson) and A . minor (Hodgson) appear to be circumpolar in distribution. Other species such as Ecleipsothremma spinosa (Hodgson) are known from scattered regions in East and West Antarctica, and will probably also prove to be circumpolar.

Radiative Evolution in the Pycnogonida Some genera appear to have a disproportionate number of species in the Antarctic compared with the total number of species known for the world. TABLE11. NUMBER01

ANTARCTI0 S P E C I E S COMPARED WITH

TOTAL KNOWN

(after Fry, 1964)

Nymphon Achelia Tanyatylum Colossendeis Pycnogonum Ammothm

Total known apeCi&9

Species present in Antarctica

110 32 20 25

30 (27%)

21 14

5 (15%) 4 (20%) 13 (62%) 3 (14%) 14 (100%)

Fry (1964) did not feel that he could postulate any reason for the successful radiative evolution of colossendeids, and possibly other Pycnogonida in the Antarctic. He did point out that the known preferred foods for Arctic colossendeids were sponges, sea anemones, alcyonarians, gorgonians and hydroids. Fry did not feel that sufficient evidence was available on relative biomass of these organisms in enough areas of the world to allow an objective assessment. There is enough

ANTARUTIC BENTHOS

63

direct evidence available now for the Antarctic benthos to be able to state that it is exactly the groups listed above which are so highly characteristic of many shelf areas. The main Antarctic families not dealt with by Fry and Hedgpeth (1969) are the families Nymphonidae and Pallenidae. The main Antarctic genus of the family Nymphonidae is the genus Nymphon and Gordon (1932) who attempted a revision has indicated some of the difEoulties encountered in dealing with this group systematically. Dr Gordon, herself, has indicated that her conclusions are tentative. She keys some 31 Antarctic and Subantarctic species of the genus, which would appear to be another good example of radiative evolution amongst Antarctic animals. Fry (1965) was able to study two live Antarctic species at McMurdo Sound, Austrodecus glaciale and Rhynchothorax australis Hodgson. He was particularly concerned with the food preferences of these two species, which occurred in comparable numbers in approximately 280 m. Specimens of Rhynchothorax were observed to ingest polyps of the hydroid Eudendrium tottoni Stechow and in experimental work associated itself with this hydroid in preference to all other potential foods offered. Austrodecus showed a marked preference for association with the polyzoan Cellarinella foveolata Waters. Fry was able to show that the h e pointed proboscis of Austrodecus glaciale would allow it to probe through the frontal wall pores of the zooecium and so gain access to the coelom of the polypides of Cellarinella. Austrodecus also requires a leg span of about 10 mm or more to provide a 6rm platform for feeding. Only Cellarinella of the available polyzoans had frontal wall pores large enough to allow the proboscis of A. glaciale to penetrate, in addition to supplying a broad, firm colony. The Discovery collections included males of 16 species carrying eggs or larvae. The dates of collection were from October to April (more concentrated from December to March). In the Magellan area all such males were collected in July (Gordon, 1932). Many Antarctic pycnogonids have been collected encrusted with other organisms. Gordon (1932) records mainly Polyzoa, Foraminifera and hydroids, and occasionally brachiopods, sponges, tunicates and serpulids. Occasional isopods have also been recorded clinging to pycnogonids. Decolopoda antarctica is usually much more heavily encrusted than D. australis, evidence presumably that D. antarctica is a fairly sluggish animal. Hedgpeth (1964, p. 45) has recorded the eggs of a prosobranch attached to the legs of Antarctic pycnogonids from Eltanin Stations 410 (61"18'5, 56"08'3O''W, 120-131 fm) and 437 (62'49'36"S, 60"40'W,

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R. K. DELL

146-170 fm). Hedgpeth supposes that the dispersal of pycnogonids is probably easier than that of the shelled gastropod concerned.

0.Crustacea 1. Cirripedia

The continent of Antarctica would hardly seem an ideal, or even a possible habitat for barnacles. It does in fact support a varied fauna of benthic forms, some of the genera presenting a wealth of varied aspects.

n

-

E

G FIQ.6. Some Antarctic cirripedes. A. B. Litoscalpellurn convexum (Nilsson-Cantell), A , young specimen, 4.35 mm long, B. full grown specimen, 15 mm total length, off South Georgia (redrawn after Nilsson-Cantell) ; C. Arcoscalpellum magnaecarinae (Nilsson-Cantell), off Antarctic Peninsula (redrawn after Nilsson-Cantell) ; D. Arcoscalpellurn compacturn (Borradaile),McMurdo Sound (redrawn after Borradaile) ; E. Litoacalpellurn discoveryi (Gruvel), McMurdo Sound (redrawn after Borradaile) ; F. G. Balhylama corolliforme (Hoek), F. (redrawn after Nilsson-Cantell), G. (redrawn after Borradaile).

The outstanding feature of the fauna taken as a whole is the extremely high percentage of lepadiform to balaniform barnacles, approximately 32 to 1 (Newman and Ross, 1971). This is correlated with the lack of a littoral fauna (amongst which balaniform barnacles are usually extremely well represented) and possibly with the geological history of Antarctica. During periods of heavy glaciation, it would be the balaniform species living in shallow water which would suffer disproportionately. The full extent of the cirripede fauna has only been slowly realized. The Challenger only just crossed the Antarctic circle but Hoek’s report (1883) on the collections supplied much information on species

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which were collected in the Subantarctic and have since been found to inhabit Antarctic seas also. Hoek also (1907) described the barnacles coIIected by the Belgica. Gruvel (1906a) published a preliminary paper on the barnacles collected by the Discovery and followed this (1907) with a complete account. He also wrote up the German South Polar collections (1909), and listed the cirripedes collected by the second French Antarctic expedition (1911). The collections made by the Terra Nova were written up by Borradaile (1916). Nilsson-Cantell contributed four papers on Antarctic cirripedes, the first (1926) b a e d on material from the Ross Sea, followed (1930%)by a paper on some South Georgian species, and two (1930b, 1939) on the barnacles collected during the Discovery Investigations. Bage (1938) wrote the account of the Australasian Antarctic collections. Heegaard (1951) described an ascothoracican, parasitic on ophiuroids at South Georgia. Boschma (1962),dealing with the Rhizocephala from the Discovery collections, showed that Briarosaccus callosua Boschma, known already as a parasite of lithodid crabs, also occurred at South Georgia. Material collected on Soviet expeditions has been written up by Zevina (1964, 1968). Utinomi (1965) recorded specimens of Hexelasma collected by Japanese Antarctic endeavours. Weisbord (1965, 1967) recorded new localities for Hexelasma, and discussed its distribution and geological significance. Ross and Newman (1969) contributed a general account of the composition of the Antarctic cirripede fauna, its distribution and relationships, and promptly made this contribution largely obsolete by a monograph (Newman and Ross, 1971) on the Antarctic forms. The two parasitic forms recorded from South Georgia are interesting but probably at the southern limit of such forms. The rhizocephalan Briarosaccus callosus has been treated in considerable detail by Boschma (1962). The species is known from off the coast of Florida and from the Bering Sea and Magellan Strait extending to the Falklands and South Georgia. All the records have been as parasites on a variety of lithodid anomuran crabs. Farther south in the Scotia Arc lithodids are not known. It will be of great interest to check if the lithodid recorded as Paralomis spectabilis Hansen by Birstein and Vinogradov (1967) from off Scott Island, also acts as a host to this rhizocephalan. This cirripede must really be considered a parasite of lithodida which has extended its range to South Georgia along with a suitable host in the shape of Paralomis granulosa (Hombron and Jacquinot). Another parasitic form, the ascothoracican Ascothorax bulbosus was described by Heegard (1961) as parasitic on the two ophiuroids, Amphiura belgicae Koehler and A . microplax Mortensen. The parasite

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occurs in the bursa of the ophiuroid, apparently with a dwarf male always in association with the full sized female. On the evidence available at present, the genus appears to be bipolar, with no occurrences between the Arctic and Antarctic species. The monograph by Newman and Ross provides a first-class illustration of the way in which the collections made since the I.G.Y. will revolutionize our concepts of the Antarctic fauna, especially the deeper water component. The area treated by Newman and Ross can hardly be covered by any single faunal designation. It is naturally enough based upon the area covered by the rich collections obtained by the Eltanin and thus covers what can only be called the Antarctic, Subantarctic and contiguous areas. The monograph deals with 85 species, 29 genera and 9 families, of which 20 species, 9 genera and one family are described as new. Not all of these new forms come from the Antarctic, nor even the Subantarctic. One of the most interesting discoveries made by Newman and Ross was the presence of the acrothoracican boring genus " Cryptophialus '' in the Antarctic. The new species tomlinsoni occurred off the Antarctic Peninsula and in the Ross Sea. The southern group of Cryptophialus was separated as a full genus, Australophialus, by Tomlinson (1969). Australophialus tomlinsoni lives in burrows in dead stylasterine corals, bryozoans and the shells of other barnacles, in depths from 300 to 641 m, unusually deep for this whole order. It is the family Scalpellidae which provides the bulk of the Antarctic benthic barnacle species, in particular the genus Arcoscalpellum. The Antarctic genera included in this family are Arcoscalpellum, Scalpellum (s. str.), Neoscalpellum, Litoscalpellum, Australscalpellum and Gymnoscalpellurn (the last three genera erected by Newman and Ross, 1971). Superficially this diversification of genera and species looks like another example of explosive speciation in Antarctic waters. However, only one of the genera listed above is endemic to the Antarctic, and a wide range of species, especially in Arcoscalpellum and Scalpellum are found in deep water in other parts of the world. The predominance of this family in the Antarctic is probably better interpreted as being simply an extension of the deep water fauna into Antarctic waters. Newman and Ross record 20 species of Arcoscalpellum from south of the Antarctic Convergence, of which no less than 14 seem to be endemic. A surprising number of these species are known so far from only one station, or from one restricted area. Eight species have been recorded only from depths greater than 1000 m, three only from depths

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greater than 4 000 m. Only two species, A . weltneri (Gruvel) and A . compactum (Borradaile) appear to have been recorded from both East and West Antarctica, perhaps a further indication of our patchy knowledge of benthic distributions rather than a biological fact which requires explanation. It may well be that our knowledge of the species of Antarctic Arcoscalpellum is much less exact than a formal listing of the species so far recorded and their known distributions would indicate. Ross and Newman (1969) pointed out that the young stages of different species are very similar although juveniles are very different from adults. From the evidence so far available only one species appears to span a very wide bathymetric range, A . brevecarinatum having been recorded from 515 to 4540m. Obviously much more material is needed before the Antarctic species can be expected to provide useful evidence for biogeography. The single Antarctic representative of the genus Scalpellum is S. vanhoffeni Gruvel. Originally described from off the Gauss Winter Station in depths from 350 to 385 m, it has now been recorded by Newman and Ross from off the South Orkneys in 298 to 403 m. The genus Litosculpellum includes seven endemic Antarctic species, L. fissicarinata Newman and Ross, L. aurorae (Bage), L. convexurn (Nilsson-Cantell), L. simplex Newman and Ross, L.walleni Newman and Ross, L. discoveryi (Gruvel) and L. korotkevitchae. Apart from L. walleni described from off Peter I Island in 4 502 m, the only species with a wide distribution pattern is L.discoveryi, recorded from the Ross Sea, off the Antarctic Peninsula and off South Georgia, its distribution perhaps governed by the distribution of large pycnogonids, to which this species normally attaches itself (Newman and Ross, 1971). The newly erected genus C7ymrwscalpellum includes the two Antarotio species, G. tarmovi Newman and Ross described from several stations off the South Shetlands, and G . leoni (Zevina) described from 69'21'5, 14'06'E (Zevina, 1968). Both are endemic to the Antarctic. Newman and Ross (1971) erected the genus Australscalpellum for the single species, A . schizmatoplacinum Newman and Ross collected by the Eltanin from off the South Shetlands and the Antarctic Peninsula. A single species of Neoscalpellum, N . schizoplacinum comes from the Southeast Pacific Basin in 4 758 to 4 804 m (Newman and Ross, 1971). The only member of the suborder Verrucomorpha represented in Antarctic waters is T'erruca (Altiverrzlca)gibbosa Hoek recorded from the Bellingshausen Sea and South Georgia, but known elsewhere from a wide area embracing the southern portions of the Indian, Pacific and Atlantic Oceans. The only other barnacle which remains to be discussed has un-

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doubtedly attracted more comment than any other Antarctic species. It is the species which has been known as Hexalasma antarcticum, which Newman and Ross (1971)have shown to be based on the adult form of an earlier described species, now B. corolliforme (Hoek). These authors have also shown that this group of corolliforme, the New Zealand Miocene B. aucklandicum (Hector) and the North Atlantic B . hirsutum (Hoek), are so different from Hexelasma that they warrant a, new genus, Bathylasma. The suborder Balanomorpha is usually divided into two families, the Chthamalidae and the Balmidae. There has always been uncertainty about in which family Hexelasma and its allies should be accommodated. Newman and Ross (1971) believe that these genera are distinct enough to require a new family, the Bathylasmatidae. Growth of knowledge of what we must now learn to call Bathylasma corolliforme has been slow, contributors following the tradition of scientific interdisciplinary effort in the Antarctic. Borradaile (1916b) described it from disarticulated valves collected as subfossils in a glacier deposit about 9 m above aea level in the Ross Sea. It has been one of the central points in the discussions concerning the methods by which organisms of many groups have been exposed on the surface of ice, which has ranged from Debenham (1919) to Debenham (1961) and thence into the discussions on anchor ice formation. Dead valves have been dredged in quantity on occasions and Utinomi (1965) and the geologist Weisbord (1967) have given recent accounts. Bage (1938) had a live specimen but most other accounts of this barnacle had been based upon dead valves. Some of Weisbord’s specimens from the Scotia Ridge gave an age of 17 000 f 360 years and would therefore be Pleistocene. Bullivant (1967, p. 66, pl. 14, p. 50) described a “ Barnacle-plate Bottom ” in the Ross Sea with many live specimens. Here on the northern edge of the deep shelf in the Ross Sea, “ Hexelasma antarcticum covers exposed erratics thickly and the dead plates have built up a deposit comprised of very little else, with almost no fine sediment ”. This station was New Zealand Oceanographic Institute Sta. A463, 7Z020’S, 174O50‘E, in 468 to 465 m. A similar bottom was recorded from the nearby Station A465 in 399 m. The U.S.S. Glacier sampled a similar assemblage about 18 miles west of Station A463, in 521 m. It is evident that a fairly extensive bed of Bathylasma occurs along the edge of the deep shelf, in an area where the lack of h e sediment indicates strong bottom currents in depths from about 400 to 550 m. Now that it has been shown that corolliforme and antarcticum are synonymous, as Weisbord (1965) had indicated might well be true, it is possible to assess its distribution. It would appear to be circumpolar in high

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latitudes, extending along the Antarctic Peninsula to the South Shetlands, South Sandwich Islands and South Georgia as well as off Kerguelen, in depths from 210 to 1 464 m. The specimens recorded by Weisbord (1965) from the Sars Bank belong to another species (Newman and Ross). A range of Quaternary deposits containing Bathylasma (= Hexelasma) fossils in McMurdo Sound has been listed by Speden (1962). I n summary therefore the Antarctic cirripede fauna contains the following elements : Briarosaccus callosus Boschma-South Georgia ; Ascothorax bulbosus Heegaard-South Georgia, endemic ; Australophialus tomlinsoni Newman and Ross-circum-Antarctic, endemic; Arcoscalpellurn.-(2O species of which 14 are endemic) ; Scalpellum vanhoffeni-circum-Antarctic ; LitoscaZpeZlum-(7 endemic species) ; Gymnoscalpellum--(2 endemic species) ; Neoscalpellum schizoplacinum Newman and Ross-Southeast Pacific Basin, endemic ; Australscalpellumschizmatoplacinuwz-East Antarctica,endemic ; Verruca (Altiverruca) gibbosu-Almost cosmopolitan, East Antarctica ; Bathylasm corolliforme-circum-Antarctic, known also from Kerguelen. The known Antarctic cirripede fauna therefore totals 37 species, of which 28 are endemic. 2. cumaceu

Antarctic Cumacea have been collected by most of the expeditions. Reports on the group have been prepared by Hansen (1908), Zimmer (1907a, 1907b, 1908, 1909, 1913), Calman (1907, 1917a, 1917b, 1918), Hale (1937) and Gamo (1969). Lomakina (1968) summarized previous collections and published maps showing the distribution for species collected by Soviet expeditions. Jones (1971) described collections from the Ross Sea, and recorded the species present in a collection from the South Shetlands . Jones (1971) considered that 28 species had been recorded from the Antarctic with 12 other species from the Subantarctic. Combining the data from Lomakina (1968) and Jones (1971) gives a total of 41 species from the Antarctic and Subantarctic of which 93% are endemic to the

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R . K. DELL

area. No genera are endemic. Of the 38 endemic species 17 are confined south of 60%. Existing records are too sparse to draw any proper conclusions. Some shallow water species such as Cyclmpis gigas Zimmer, Leucon antarctica Zimmer, Eudorella gracilior Zimmer, Diastylis helleri Zimmer and Leptostylis crassicuuda Zimmer appear to be circumpolar in distribution, E . gracilior and D . helleri extending as far north as South Georgia. Lomakina (1968) stressed that, although not many Antarctic species had been recorded, the fauna was systematically varied. A large number of the species (1 8) belong to genera which mainly live in cold water in the Northern Hemisphere, e.g. Diastylis, Leptostylis, Leucon, Eudoretla, Lamprops and Hemilamprops. The Pacific genus Diastylopsis which does not occur in the Arctic is represented by two Antarctic species. The genera Curnella and Campylaspis which are mainly warm water genera have eight Antarctic species between them. The presence of the two genera, Vawnthompsonia (with two species) and Cyclaspis (also two species) of the warm water family Bodotriidae makes up an unexpected element. The high Antarctic (Antarctic Continent) species form a compact isolated group with 14 endemic species, while the low Antarctic group (South Georgia and Kerguelen) has 11 species found nowhere else. Only seven species are found in both major areas. Both Lomakina (1968) and Jones (1971) presented keys to the Antarctic and Subantarctic cumaceans, and Lomakina gave distribution maps showing the known patterns for most species. 3. Ostracodu

On the whole the Ostracoda appear to be one of the neglected Antarctic groups. No reports on the group have eventuated from many of the Antarctic expeditions. Thus apart from a relatively minor paper on forms from South Georgia, only two papers have appeared on the benthic forms since 1919. Brady (1907) recorded the results of the National Antarctic Expedition, 1901-04, Daday de Dees (1908, 1913) those of the two French Antarctic expeditions, Mueller (1 908) those of the German South Polar Expedition and Scott (1912) described the collections of the Scottish National Antarctic Expedition. Chapman (1916a, b, c) recorded species from two sets of raised deposits in the Ross Sea, and from the sounding deposits obtained by the British Antarctic Expedition, 1907-09 and (1919) the ostracods from the Australasian Antarctic Expedition. There was then a long gap in interest in the group until Benson (1964) contributed a paper on Ross

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Sea forms. Skogsberg (1928, 1939) has written two papers on species from South Georgia. Neale’s (1967) contribution based upon 1 020 specimens belonging to 26 species from Halley Bay, Coats Land is important in that it is based upon a reasonably sized sample. This is brought properly in perspective when it is realized that in terms of the

FIG.7. Some typical Antarctic amphipods; A. Epimeria maorodonta Walker, McMurdo Sound (redrawn after Walker) ; B. Acanthonotozoma australke Chilton, 7I022’S, 16’34‘W (redrawn after Chilton); C. Orchomenella franklini Walker, Ross Sea, (redrawn after Walker) ;D, Shackletonia robusta Barnard, South Shetlands (redrawn after Barnard) ; E. Dodecasella elegana Barnard, South Georgia (redrawn after Barnard).

podocopid ostracod fauna, Mueller recorded 34 species, Brady two, Daday three and Benson seven identified forms. Neale’s conclusions therefore allow some discussion of circumpolar distribution of the group almost for the f i s t time. There is obviously much difficulty in comparing faunas from East and West Antarctica at our present stage of knowledge and Neale’s (1967) attempts to evaluate the nomenclature

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R. IS. DELL

used by the earlier workers, particularly shows the need for modern systematic treatment of the Antarctic collections which must exist either as collections or incorporated in sediment samples. Neale was reduced effectively to comparisons with the species listed by Mueller (1908) and Benson (1964) from East Antarctica. Of the Halley Bay fauna 16 species (62%) are the same as ones recorded by Mueller from his fauna a t Gauss Station (42% of this fauna). Similarly eight of the Halley Bay species (31%) are listed by Benson from the Ross Sea (62% of his fauna). It is extremely likely that the species occurring in common in these three collections represent a strong circumpolar element, e.g. Bairdia labiata (Miiller), Paradoxostoma antarcticum Miiller, P. hypselum Miiller, Sclerochilas antarcticus Miiller, S. meridionalis Miiller, S. reniformis Miiller, Antarcticythere laevior (Miiller), Bythoceratina dubia (Miiller), Xestoleberis rigusa Miiller, Myrena meridionalis (Miiller), Loxoreticulatum fallax (Miiller), Hemicytherura anomala (Miiller), H . irregularis Miiller, Cytheropteron gaussi Miiller, Copytus elongatus Benson, Cativella bensoni Neale, Australicythere polylyca (Miiller), and Patagonacythere devexa (Miiller). Three species were very well represented in both general areas. Australicythere polylyca and Loxoreticulatum fallax were common at Halley Bay, Gauss and the Ross Sea while only one species, Patagomythere devexa is common to Halley Bay (and Gauss) and to South Georgia. This species also extends to the Magellan area. There appear to be some few a m t i e s with forms from off Kerguelen and Heard Islands but Subantarctic faunas in general seem so poorly known that comparisons become rather forced.

Amphipoda (Fig. 7) For all the number of pages that have been published on Antarctic amphipods we still do not have much more than a collection of catalogues (some of them admittedly very extensive) of the collections made by various individual expeditions. To gain any general impresaion of the Antarctic fauna itself or its biogeography requires a synthesis of a great many papers, and certainly some critical systematic revisions will also be required. The amphipods are still obviously a group for the specialist, any attempt by the general biologist to draw general conclusions being largely thwarted by the sheer mass of data available. The 11 main expedition reports on the group total about 1 317 pages for example. The last attempt to discuss the Antarctic fauna in a general way seems to be that of Schellenberg (1926a,b). Bate (1862) described Cyllolpus &we,C. lzccasi and Vibilia edwardsi from material collected by La ZeWe (1837-40) off the South Orkneys. 4.

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The f i s t work on East Antarctic species seems to be Walker’s (1903) account of the collections made by the Southern Cross. Walker also reported on the collections made by the Discovery (1906) and the National Antarctic Expedition (1907). Chevreux (1906, 1911b, 1912, 1913) published preliminary accounts and the definitive reports on the two French Antarctic expeditions. In 1911(a) he published a separate paper on the amphipods of the South Sandwich Islands. Chilton (1912) contributed the section on amphipods to the reports of the Scottish National Antarctic Expedition, and (1925) wrote on the fauna of the South Orkneys. Monod (1925a, 1925b, 1926) reported on the collections made by the Belgica. Schellenberg (1926) wrote up the amphipods of the German South Polar Expedition. Barnard contributed a lengthy account of the Terra Nova (1930) collection and a short account (1931) followed by a massive volume on the collections of the Discovery Investigations (1932). The material collected by the Australasian Antarctic Expedition was written up by Nicholls (1938), that by the U.S. Antarctic Service Expedition by Shoemaker (1945). The collections of the Norwegian Antarctic Expedition were described by Stephensen (1947). Ruffo (1949)contributed the second part of the report on the amphipods of the Belgica. Oldevig (1961) described a new species from the South Sandwich Islands. Hurley (1965a, 1965b) distinguished between the common species of Orchomenella in the Ross Sea and described one of them as new, and re-described some of Walker’s early types. The amphipod fauna of South Georgia was treated in many of these publications, a few have been concerned with South Georgia alone, e.g. Pfeffer (1888), Chilton (1913) and Shoemaker (1914). Schellenberg (1926)was concerned solely with Gammaridea. Of the Antarctic shelf forms, his records at that date showed that threequarters were confined to one area of the Continent. He could list only seven species with a circumpolar distribution, i.e. Waldeckia obesa Chevreux, Tryphosa murrayi Walker, Orchomenella pinguides Walker, Orchomenopsis chilensis f. rossi Walker, Thaumatelson herdmani Walker, Epimeria macrodonta Walker and Eusirus microps Walker. Chevreux (1913) on the evidence available to him noted that 11 families of the Gammaridea and the family Caprellidae were absent from Antarctic waters. The German South Polar Expedition collected four of these families of the Gammaridea and the Caprellidae, while another family, the Lafistidae, was collected by the Terra Nova. Barnard (1932) could therefore report that only a few of the smaller families like the Stenothoidae, Cressidae, Anamixidae, Ingolfiellidae and Argissidae were still not known from the Antarctic.

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Barnard (1932) in his report on the Discovery collections covered the area from southern South America, the islands of the Scotia Arc, particularly South Georgia, and the Antarctic Peninsula. He added the family Atylidae to this fauna and described a new family, the Pagetinidae, from the material collected. He noted that there was a strong resemblance between the amphipod faunas of the Antarctic Peninsula and the Ross Sea, particularly evidenced by the Acanthonotozomatidae and the Epimeridae. Schellenberg (1931) was concerned with the suborders Gammaridea and Caprellidea from a variety of Swedish and German expeditions to the Magellan Region, the islands of the Scotia Arc and to the Antarctic Peninsula. This report therefore covers much the same ground as does that of Barnard (1932) which appeared a year later. Barnard did not have access to Schellenberg’s paper until after his own had gone to press, and as Barnard noted only some of the major changes necessitated by Schellenberg’s work could be made in his own paper. Schellenberg listed some 290 species and varieties from the area he dealt with and tabulated their distribution patterns from Chile to West Antarctica. He recorded 91 species of benthic amphipods from South Georgia. Of these 29 species were considered endemic. Of the other species recorded from South Georgia, 14 ranged from the Magellan Region to the South Orkneys or to the Antarctic Continent, 18 were known also from the Magellan Region and a further 26 species were also recorded from the islands to the south and from the Antarctic Continent. Two lyssianassid amphipods are particularly common in McMurdo Sound and since they are readily attracted to bait have been frequently caught by most observers who have used traps of one sort or another. Until quite recently only one species was considered to be represented, Orchornenella rossi Walker, but Hurley (1965) showed that there were two species, the commoner one being undescribed. This second species was named Orchomenella plebs by Hurley. Presumably all previous references to 0. rossi really refer to both species. Walker (190.7) quoted T. V. Hodgson, the indefatigable naturalist on the National Antarctic Expedition 1901-04. Hodgson recorded lifting a trap from 56 fm on 17 May 1902, ‘‘ The trap contained about 10 000 of these amphipods.. . .Four fish were in the trap, one of them had been reduced to an absolute skeleton; on another the amphipods hung by their ‘ teeth ’ in a compact mass, completely concealing their victim. Its skin had disappeared, and I judged also about a millimetre of flesh, but the animal was still alive; the other two fish were presumably waiting their turn.”

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“From that date until 25th October 1902, this species was taken in numbers varying between 10 000 and 30 000 at a haul, and this at all depths to 125 fm.” Hodgson was of the opinion that these great masses normally fed on the carcases of seals which had died when unable to find a breathing hole in the ice. The amphipod Bovallia gigantea (Pfeffer): The life history of this large (up to 60 mm) reddish amphipod has been studied in the South Orkneys by Thurston (1968). Bovulliu gigantea has been recorded from the Antarctic Peninsula, the South Shetlands, and South Sandwich Islands, and South Georgia, as well as from the South Orkneys, from low water mark down to about 40m. It has been commonly found associated with the large algae Desmarestiu anceps Montagne and Phyllogigus grundifolius (A. and E. S. Gepp) Skottsberg. I n the South Orkneys it appears to be rather sedentary throughout the year. Eggs are deposited in the brood pouch in late February and March, but early development is slow and hatching does not take place until September and October. As in many other malacostracans, the number of eggs produced is in direct proportion to the size of the female, ranging from 80 in a specimen 41 mm in length to 139 in a female 49 mm long. Breeding appears to be seasonal and regular. Females reach breeding maturity at an age of about 40 months, males at about 28 or 29 months. The evidence available indicates that females die after the brood is released, though some males may achieve two breeding seasons, dying off after breeding for the second time at about 40 months age. The general associations of Antarctic amphipods have hardly begun to be recorded. The necrophagous habits of Orchomenella have been mentioned. Nine species of amphipods commensal in sponges, and two species commensal in the branchid chamber of ascidians were listed by Barnard (1932). 6 . Isopoda and Tanaidacea (Fig. 8 )

The first isopod of Antarctic facies to be described was the Magellanic Xerolis paradoxa, described by Fabricius (1776) as Onisczcs paradoxa. The first Antarctic forms proper were described by Eights (1833, 1852, 1866) from the South Shetlands. The Challenger did not obtain any restricted Antarctic isopods although the reports by Beddard (1884a, 1884b, 1886) supplied a basic knowledge of Southern Hemisphere members, and Subantarctic species in particular. Pfeffer (1887) described the collections from South Georgia made by the German expedition of 1882-83.

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As with so many other groups the high latitude isopods were not known until the beginning of the twentieth century. Hodgson (1902) wrote up the isopods collected by the Southern Cross, and by the National Antarctic Expedition (1910). Richardson described the material collected from the f i s t and second French Antarctic expeditions (1906a, 1906b, 1908, 1913) and a collection from the South Sandwich Islands (1911). Stebbing (1914) reported on the collections of the

Fro.8. Three typical Antarctio isopods. A. &TOl68 glacialia Tattersall, Ross Sea (redrawn after Tattersall);B. alyplonotzrsantarcticua Eights (aczltuaform),Ross Sea (redrawn after Hodgson); C. Amtarcturw, polaria (Hodgson),Ross Sea (redrawn after Tattersall).

Scottish National Antarctic Expedition. Reports on subsequent expeditions have appeared as follows : German South Polar (VanhlSeffen, 1914), Terra Nova (Tattersall, 1921) the Belgica, well out of chronological order (Monod, 1926), Swedish Antarctic (Nordenstam, 1933), B.A.N.Z.A.R.E. (Hale, 1946, 1952) and Norwegian Antarctic (Stephenson, 1947). Two long reports by Sheppard described some of the collections made b y the Discovery Investigations, the Serolidae (Sheppard,

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1933) and the Valvifera (Sheppard, 1957). The group in the Antarctic has received little attention in the last few decades, however, even the Discovery collections not having been written up completely. Nor was there any general account of the Antarctic fauna nor any attempt to analyse its relationships or biogeography. The large paper by Kusakin (1967) describing the results of recent Soviet expeditions and containing a very full discussion of distribution and faunal relationships is particularly welcome. Kusakin also presents a short historical summary of all work on the group in the Subantarctic and contiguous areas and indicates areas for which information is lacking. He stresses that a group such as the isopods, since most are bottom dwelling animals, do not migrate extensively, carry their young with them and occur in numbers in most seas, are a particularly useful group to consider for biogeographical evidence. Kusakin (1 967) considered that 180 species of Isopoda and Tanaidacea were to be found in the Antarctic. Of these 66% were endemic to the Antarctic. Of the 69 genera represented only six are endemic, i.e. Zenobianopsis, Clyptonotus, Dolichiscus, Ectias, Notoxenus and

Echinomunna. The Antarctic isopods represent no less than 26 of the 30 families known from the Southern Hemisphere outside the tropics and subtropics. The ones missing are three widely dispersed families (Jaeropsidae, Corallinidae and Cymothoidae), and one endemic to the Patagonia region (Xenarcturidae). Far more than for most other groups investigated the Antarctic isopod fauna is much less restricted. One of the characteristics of the Antarctic fauna is the abundance of species down to 400 or 700 m, instead of a falling off in numbers in depths of 200 m or more as in other parts of the world. The genera best represented are Serolis with 23 species and Antarcturus with 20. Although not confined to the Antarctic these two genera are undoubtedly best represented here. The number of species steadily decreases to the north. The family Munnidae with nine genera and 30 species, is also well represented. The family Idoteidae, which is usually well represented with genera and species, has only three genera in the Antarctic, two of which, Glyptonotus and Zenobianopsis are endemic. Kusakin (1967) divides the Antarctic for purposes of analysis into four zones. 1. From Eights Coast to Adelie Land (lOOoW to 140"E)-" Pacific Ocean Sector ". 2. From Wilkes Land to Princess Ragnhild Coast (140"E to 15"E)" Indian Sector ". 3. Princess Martha Coast to the Bellingshausen Sea (16"E to l00"W)

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including Graham Land and the South Shetland Islands-" Graham Land ". 4. South Georgia, Shag Rocks and the South Sandwich Islands, including Bouvet Island. The number of species of isopods and tanaids occurring in each zone together with their occurrence elsewhere in Antarctica can be seen in Table 111. TABLEI11 Number of apeciea of iaopoda Common to

Pacific Ocean Sector Indian Sector Grahham Land

Total

Endemic

46 103 69

6 47

17

Pacific

Common

Common

Ocean Sector

to Indian

to Grahrn

Sector

Land

32

26 31

32 26

31

-

Kusakin stressed that the areas have been unevenly and inadequately studied. The large number of species recorded from the Indian Sector is due to the fact that intensive collecting by the Gauss and the Soviet investigators in one area has brought to light a whole range especially of small species. The degree of endemism within this zone may therefore only be apparent, not real. Kusakin concluded that the species of the fauna from the Antarctic Continent and the associated islands including South Georgia are much more similar amongst themselves than they are to those of any other area. He therefore believes that this fauna makes up a single Antarctic fauna, but is prepared to consider South Georgia as " a kind of province of the Antarctic region ". On the evidence available he also divides the Antarctic continent into Ross and Davis districts with the boundaries left uncertain. He also treats Graham Land, the South Shetlands and South Orkneys as " a specific west Antarctic transitional province ". The Antarctic fauna of 120 species is divided into seven elements, divided on the basis of their distribution patterns. 1. An East Antarctic group, includes 62 species confined to the shelf and the continental slope of the Antarctic continent, excluding Graham Land. This is essentially a high Antarctic stenothermal group. Highly characteristic are two species of Zenobianopsis and the monotypic genera Echinomunna and Notoxenus. Eleven species of the family

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Munnidae, seven of Antarcturus, and four of Serolis are commonly found. 2. A West Antarctic group (narrow sense) characterized by the 16 species endemic to Graham Land and the associated islands (South Shetlands and South Orkneys). Four of these are species ofserolis,three of Antarcturus, and two belong t o the family Munnidae. The genus Dolichus (represented in East Antarctica by D. meridionalis Hodgson) has a related West Antarctic species, D. pfefleri Richardson. 3. A circum-Antarctic group is represented by 14 species which extend around the continent. These include species of Cirolanu, Aega, Serolis, Leptanthura, Antias, Edotia, Microarcturus and Stenetrium. 4. A Low Antarctic group, with 15 species endemic to South Georgia, Shag Rocks, the South Sandwich and Bouvet Islands. These include four species of Serolis, three of Desmosomu, two of Antarcturus and two of Munna. 5. A West Antarctic group (wide sense) contains three species ranging from South Georgia to western Antarctica, one species from each of the genera, Plalcarthrium, Antarcturus and Microarcturus. 6. Three species recorded only from East Antarctica and South Georgia, Eurycope frigida Vanh6ffen, Austrosignum glaciale Hodgson and Ianthopsis nasicornis VanhBffen. 7. A pan-Antarctic group, occurring on the coasts of Antarctica and extending to the marginal zones of the Antarctic. This group includes the two monotypic genera Ectias and Glyptonotus. South Georgia: Some 58 species of isopods and tanaids have been recorded from South Georgia (Kusakin, 1967). Of these 14 species are endemic to South Georgia, 25 are common to the Antarctic Peninsula, and 14 are known also from East Antarctica. However, these are not exclusive relationships since many of these species are also found in the Subantarctic. Thus of the 58 species known from South Georgia, 21 species also occur on Kerguelen, 15 on the Falklands and 12 off Tierra del Fuego (Kusakin, 1967). Relationships of the fauna a t the generic level are stronger with the Antarctic than with the Subantarctic. Glyptonotus antarcticus Eights is a large idoteid isopod which is widely distributed throughout the Antarctic having been recorded from the Ross Sea, the Antarctic Peninsula, the South Shetlands, the South Orkneys and South Georgia in depths from 1 to 585 m. Although described by Eights from the South Shetlands in 1852 and discussed by practically every worker on the systematics of southern isopods it is only recently that much has been recorded of its biology. Dearborn (1967) wrote on its food and reproduction, based on studies carried out at McMurdo Sound, and White (1970) has recorded some aspects of its

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breeding biology at the South Orkneys. The species has also been mentioned in describing associations of animals from relatively shallow water, e.g. Price and Redfearn (1968) at the South Orkneys, McCain and Stout (1969) on the Antarctic Peninsula and Gruzov and Pushkin (1970) in the South Shetlmds. I n McMurdo Sound, Glyptonotus lives on wide range of substrates in depths down to at least 585 m. Specimens collected by Dearborn ranged from 51 to 111 mm in total length, a giant amongst isopods. The gut contents, examined in 118 adults, revealed a wide range of food. The commonest occurring foods were ophiuroids (52.3%), gastropods (19.3%), isopods (17.4%) and echinoids (14.7%). Of the prey identified to species the following are noteworthy : Ophiacanthu antarctica Koehler and Ophiurolepis gelida (Koehler) (the two commonest brittle stars in the area), Margarella refulgens (Smith) (a very common small trochoid gastropod), Glyptonotus, Sterechinus neumayeri (Meissner) (an echinoid) and Anthometra adriani (Bell) (one of the two common crinoids). Other groups represented were bivalves polychaetes, pycnogonids, sponges, brachiopods and algae. Many of the specimens were collected in baited traps so that the presence of seal meat and fish used as bait is to be expected but does indicate that this species may be necrophagous. Many of the specimens also contained the amphipod Orchomenella,but since this species is also attracted to bait in enormous numbers its apparent importance as food for Glyptonotus may have been artificially induced by the trapping technique. From an analysis of the gut contents of specimens taken from different substrates Dearborn concludes that availability of food is more important than the type of prey. This seems another successful Antarctic species which has a wide range of foods. Interesting adaptations are the modifications of the three anterior pairs of legs to form prehensile organs, the large powerful mouthparts, and divided thoracic somites which allow for great expansion to accommodate large quantities of food. The species can swim actively with the ventral surface uppermost. Dearborn concludes that the ecological role of Clyptonotus is ‘‘ as a large predator and scavenger on the bottom ” perhaps taking the place of crabs and lobsters in the temperate benthos. Dearborn found little evidence that Glyptonotus was preyed upon by other animals, except that small examples were eaten by the common bottom fish, Trematomus bernacchii Boulenger. Once males reach maturity they grasp an immature female and the pairs remain associated. White recorded periods of attachment up to 190 days. During this period males may change females from time to time, but the pair bond seems much more binding for the 30 days or so

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before the moult which ushers in maturity for the female. After fertilization the female deposits the eggs in the marsupium where further development takes place. The total number of eggs produced varies, largely with the size of the female. Dearborn recorded from 356 to 1 020, mean 746 at McMurdo Sound. White gave a mean of 512 for Signy Island in the South Orkneys. Within the marsupium the development from egg to larvae to final release took from 577 to 626 days (White). Most adult females studied in the South Orkneys died shortly after the brood had been released, and most males died after fertilization. In contrast to many other Antarctic animals studied in detail, there appears to be no fixed general breeding season neither at McMurdo Sound, nor at the South Orkneys, the species breeding throughout the year. 6. Decapoda

The Antarctic decapod fauna is sparse. Three species of natants are known from the Antarctic continent. Two of these, Chorismue antarcticus (Pfeffer) and Notocrangon antarcticus (Pfeffer) were originally described by Pfeffer (1 887) and have since been recorded by most Antarctic expeditions. They are both apparently circum-Antarctic. A third species, Spirontocaris antarcticus Hale was described by Hale (1941) from off Adelie Land. A subspecies of Notocrangon antarcticus has been described from East Antarctica as Notocrangon antarcticus gracilis Borradaile. The two common species of Chorismus and Notocrangon have been recorded from various Antarctic localities by Calman (1907),Borradaile (1916),Coutihre (1917), Bage (1938) and Hale (1941). Yaldwyn (1965) has summarized all records of Decapoda from Antarctic and Subantarctic waters. Chorismus antarcticus also extends to the Magellan region, the other two species Notocrangon antarcticus and Spirontomris being confined to Antarctic waters. These genera are widespread in other areas. Yaldwyn has indicated that the record of the hymenosomid crab, Halicarcinus planatus (Fabricius), from the South Orkneys (Stebbing, 1914) should be disregarded although it is a widespread Subantarctic species. The fact that it is still unknown from South Georgia which would be a much more congenial habitat for a hymenosomid rather rules against the South Orkney record. The anomuran crab Paralomis spectabilis Hansen, has been recorded from the Antarctic waters (Birstein and Vinogradov, 1967). This species occurs elsewhere only in the North Atlantic, and if the identification in this difficult group is correct this is a new piece of evidence for bipolarity.

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South Georgia has a fauna of three species of prawns, Notocrangon antarcticus and Chorismua antarcticus which are both Antarctic species, and Campylonotus vagans Bate, a South American species (Zarenkov, 1968).

Boschma (1962) discussing the rhizocephalan parasitic barnacle, Briarosaccus callosus Boschma, records its presence on two different lithoid crabs, Paralomis granulosa (Hombron and Jacquinot) and Lithodes antarcticus Jacquinot from the Discovery Collections, and both from South Georgia.

P. Mollusca The Mollusca of the Antarctic have received a great deal of attention, perhaps at times too much attention. The most important expedition results on Antarctic benthic Mollusca have been : Watson (1886), Smith (1902), Pelseneer (1903), Thiele (1906), Lamy (1906a, b, c), Eliot (1907), Melvill and Standen (1907), Smith (1907), Thiele (1908), Strebel (1908), Lamy (1911a, b), Hedley (1911), Melvill and Standen (1912), Thiele (1912), Smith (1915), Hedley (1916a, b), Vayssihre (1916), Burne (1920, anatomy), Eales (1923, anatomy), Odhner (1926, 1934), Bergenhayn (1937), Cotton (1937), Odhner (1944), Bartsch (1945), SootRyen (1951), Powell (1951), Gaillard (1954), Powell (1958), Dell (1964), Arnaud (1965) and Soot-Ryen (1965). Nicol (1966) has published a fully illustrated, systematic revision of Antarctic bivalves. An extremely useful checklist of Antarctic and Subantarctic Mollusca was published by Powell (1960). Clarke (1961) described some abyssal forms from the South Atlantic and a general account of the composition, distribution and relationships of Antarctic and Subantarctic Mollusca appeared in 1965 (Powell, 1965). The writer (Dell, 1964b, 1965, 1968) has contributed three short accounts of Antarctic benthic Mollusca, their distribution, zoogeography and some of the problems associated with future work. Many general reports have treated Mollusca from South Georgia but the following papers have been concerned only with this group: Martens and Pfeffer (1886), Dall (1914) and David (1934). The most recent general discussion of the Antarctic benthic Mollusca family by family is given in Powell (1965). This account includes Subantarctic records as well. Some of the systematics has changed slightly since this account but the basic picture remains the same.

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1. Amphineura

Antarctic chitons have also often been treated in general works on Mollusca but the following papers refer to this group alone: Thiele (1906,1908,1911),E. A. Smith (1907),Vayssibre(1916),Odhner (1923a), Bergenhayn (1937), Cotton (1937),Castellanos (1959) and A. G. Smith (1961). Aplacophora seem to be not uncommon in Antarctic seas. A few reports have appeared on the group, e.g. Nierstrasz (1908), Plate (1908d) and Thiele (1913), but large collections still await treatment. The shelf of the Antarctic continent excluding the Weddell Sea, the Antarctic Peninsula and the Bellingshausen Sea, supports only five chitons :

Lepidopleurus kerguelensis (Haddon) (0-1 080 m) ; Lepidopleurus belgicae (Pelseneer) (500 m) ; Callochiton gaussi Thiele (0-650 m) ; C . steineni (Pfeffer) (2P300 m) ; Nuttalochiton mirandus (Thiele) (135-640 m). Of these Lepidopleurus belgicae has not been recognized since its original description, but the other four are very wide ranging, almost certainly circum-Antarctic. The relationships of this small Antarctic chiton fauna are not difficult to trace. Lepidopleurus belgicae is uncertainly placed in this genus, and cannot be discussed until its true position is known. Lepidopleurus kerguelensis is widely distributed in the Subantarctic and is related to a series of forms from the Magellan area, and in New Zealand. The group to which the closely allied Callochiton gaussi and C . steineri belong is also well represented in the Magellanic region, with other species on the islands of the Scotia Arc, in the Subantarctic Islands, and in New Zealand. Nuttalochiton mirandus (previously considered to belong to the monotypic endemic Antarctic genus Notochiton) has allied forms in the Magellanic region, one of which has also been recorded from the Weddell Sea. Another group of species has Subantarctic or Magellan distributions or relationships, the individual members extending southwards to varying limits through the islands of the Scotia Arc. Hemiarthrun setulosum Dall (well-known as a chiton which broods its young) is widely distributed in the Subantarctic and the Magellan area and extends through South Georgia and the South Orkneys to the Antarctic Peninsula. Tonicina zschaui (Pfeffer) extends from the Magellan area through South Georgia and the South Shetlands to the Antarctic Peninsula.

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The range of Callochiton bouveti Thiele starts from the Falklands, and includes South Georgia, the South Orkneys, the South Shetlands and the Antarctic Peninsula. As its specific name indicates it also occurs off Bouvet Island. Ischnochiton dorsuosus Haddon has been recorded from the Magellan region, South Georgia and the Antarctic Peninsula. Chuetopleura brucei Iredale was described from the South Orkneys and has so far been recorded from no other locality. The genus Chaetopleura is well represented in southern South America. The Magellan species Nuttalochiton hyadesi (Rochebrune) has been recorded from the Weddell Sea (Castellanos, 1959). There is thus a steady fall off in the number of chiton families as one moves down the Scotia Arc to the Antarctic Peninsula and extends east and west of it around the Antarctic Continent. 2. Scaphopoda (Fig. 9) There are very few Antarctic scaphopods, only five species having been recorded. Records of the group have often been included in general papers on Mollusca but the following four refer to Scaphopoda alone : Jaeckel (1932), Odhner (1931), and Plate (1908a, b). The most recent summaries of the fauna have been included in papers by Odhner (1944) and Dell (1964b).

The species currently known from Antarctic waters are : Dentalium eupatrides Melville and Standen, recorded only from 71'22's 16'34'W in 2 579 m. Dentalium (Fissidentalium)majorinurn Mabille and Rochebrune, Southern Chile, the Magellan Region, the Patagonian shelf, Falkland Islands, South Shetlands and circumpolar around the Antarctic Continent. Cadulus thielei Plate, Gauss Station, 380-385 m, Ross Sea. Cadulue (Polyschides) dalli antarcticum Odhner, South Orkneys, South Shetlands, probably circum-Antarctic. ? Xiphonodentalium minimum Plate, Gauss Station, 3 423 m.

No Scaphopoda have as yet been recorded from South Georgia although the molluscan fauna must by now be well known. The correct identity of Siphonodentalium minimum is still in doubt, and Cadulus thielei and Dentalium eupatrides have been recorded only from very restricted areas. Additional species may well be collected from deep-water stations but Dentalium (Fissidentalium) majorinurn and Cadulus (P.)dalli antarcticum are the only common species in moderate depths. The Dentalium also occurs off southern South America, and the nominate subspecies of Cadulus dalli (which is very closely allied to

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FIG. 9. Distribution of Antarctic Scaphopoda (data from Dell, 1969). 0 Cadulus Cadulus thielei; (Polyschidea) dalli antarctkw; 0 Fkwidentaliurn majorinurn; 0 8iphonodentalium minimum; 'I Denkzlium eupatridea.

the Antarctic form) comes from the Magellan Region. Neither of these forms appears to have any close relatives in the rest of South America although the scaphopod fauna of this area is poorly known. They may both be considered to be elements of the " old Antarctic fauna which have extended to South America. Neither species has any close relations in South Africa, southern Australia or New Zealand. ))

A.I.B.-lo

4

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3. Cephalopodu

The benthic cephalopods from Antarctic seas have been treated by Joubin (1903, 19050, 1906, 1914), Hoyle (1907, 1912), Massy (1916), Berry (1917), Thiele (1921), Odhner (1923b), Robson (1930), and in scattered references through the two volumes of his monograph of the recent Cephalopoda (Robson, 1929, 1932), Dell (1959), Taki (1961), and Nesis and Propp (1968). The composition and distribution of benthic Antarctic cephalopods are still relatively poorly recorded. The writer (Dell, 1959) listed the benthic forms as : Pareledone churcoti (Joubin), P. turqueti (Joubin), P. adelianu (Berry), P. polymorphu (Robson), P. hurrissoni (Berry), P. untarctica (Thiele), (?) Graneledone setehos Robson, Bentheledone albidu (Berry), B. rotunda (Hoyle), Thuumeledone gunteri Robson, Grimpoteuthis mawsoni (Berry) and Cirroteuthis glacialis Robson. Since then Taki (1961) has described two new eledonids, Megaleledone senoi (the genus also being described as new) and Pareledone umitakae. Both species were collected at 6'7'51.5'5 33'13.5'E in 630680 m. Amongst the Octopoda the dominant Antarctic forms are the eledonids which can be distinguished a t sight from the genus Octopus by the fact that the suckers on the arms are arranged in a single row (uniserial) rather than in the double row (biserial) of Octopus. Species of Octopus with biserially arranged suckers occur a t Kerguelen, a t Campbell Island and in Tierra del Fuego. South of these areas the Octopoda are represented by the uniserial eledonids and two species of the Cirroteuthidae (Grimpoteuthis mawsoni and Cirroteuthis glacialis). The range of eledonid genera, Pareledone, Graneledone, Bentheledone, Thumeledone and Megaleledone may well represent another example of adaptive radiation in the Antarctic. Robson (1932, pp. 51,256) discussed the relationship of these eledonid forms and concluded that they were probably diphyletic. He therefore classified Eledone and Pareledone in the subfamily Octopodinae and Graneledone, Thuumeledone, and Bentheledone in the subfamily Bathypolypodinae. This arrangement can only be considered to be provisional. Some of the " genera " are very poorly known. As regards distribution in the Antarctic, too few records are available for useful discussion. Pareledone churcoti is certainly, and P . turqueti is probably, circum-Antarctic. These two species reach as far north as South Georgia. Nesis and Propp (1968) have recorded a specimen of Megaleledone senoi Taki from the Davis Sea weighing 6 200 g with the body 28.5 cm

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long and the largest tentacle 48-0cm in length. This is the largest Antarctic octopus. Cephalopod beaks have been recorded from the stomachs of Weddell seals (Leptonychotes weddelli (Lesson) by Berry (1917), Bertram (1940) and Dearborn (1965b) and can in places form a significant part of the food. At McMurdo Sound the main species taken seems to be Pareledone churcoti. 4. Gastropoda

Although restricted in the number of families represented, the Antarctic gastropod fauna is varied with some families and genera developing a range of species. Some families have only one or two representatives. Thus the Scissurellidae has Scissurella petermannensis Lamy recorded only from the South Orkneys, and Schixotrochus euglyptus (Pelseneer)widely distributed in Antarctic waters and reaching as far north as the Burdwood Bank. The Fissurellidae is represented by the two genera Puncturella and Parmaphorella. Patinigera is the only genus of the widespread limpet family, Patellidae, to enter the Antarctic with Patinigera polaris (Hombron and Jacquinot) extending as far south as the Antarctic Peninsula although other species of the genus occur in southern South America, the Falklands, Kerguelen and Macquarie Islands. Leptocollonia with two species is the only genus of the alrnost ubiquitous family, Turbinidae. The family Marginellidae is perhaps rather a surprising occurrence in Antarctic waters with two rather closely allied species of Marginella. Other families are very well represented. Nine genera of medium sized ti0 small forms of Trochidae are found in Antarctic waters with a range of rather colourless, featureless species in each. The family Littorinidae (Fig. 10) contains some five Antarctic genera and subgenera. The genus Laevilitorina has four species, L. granum Martens and Pfeffer, L. pygmaea Martens and Pfeffer, L. umbiliata Martens and Pfeffer and L. venusta Martens and Pfeffer confined to South Georgia, two species L. bennetti Preston and L. latior Preston, confined to the Falklan d Islands, one species L. caliginosa (Gould) widely distributed from Kerguelen and Macquarie Islands, to Tierra del Fuego, the Falklands, South Georgia, and the South Orkneys and South Shetlands, and L. antarctica (Smith) which occurs on the Antarctic Continent and East Antarctica. The other genera Laevilitorina (Corneolitorina), Laevilacunaria and Laevilacunaria (Pellilacunella) occur in sections of the Scotia Arc with occasional spot records from the Subantarctic. The last genus, Pellilitorina, is endemic to the range of its only two species, P . pellita (Martens) and P. setosa (Smith), one or other of which occurs

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FIG.10. Distribution of Antarctic and Subantarctic genera of Littorinidae. A = Laevilacunaria, C = Laevilitorina (Corneolitorina), L = Laevilitorina, M = Macquariella, P

=

Pellilitorina.

at Kerguelen, Heard, South Georgia, the South Orkneys and the Ross Sea. The family Rissoidae is largely a dumping ground for small featureless gastropods whose true relationships will not be properly understood until much more anatomical work can be done. The genera Subonoba, Ovirissoa and Eatoniella are commonly met, each with a range

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of species. The family Cerithiidae elsewhere has species ranging in size from several inches down to a few millimetres. The Antarctic species are all small, belonging to the genera Cerithiella, Cerithiopsilla and Eumetula. The family Trichotropidae is largely a family of cold and temperate waters. Within the restricted Antarctic region four endemic genera occur embracing seven species. The family Naticidae has adapted itself well to Antarctic conditions. The genus Amauropsis with a thick brown

FIG.11. Speciation within the buccinid genus Chlanidota.

protective epidermis has ten species in the Antarctic and Subantarctic. Amauropsis (Kerguelenatica) grisea (Martens) is circum-Antarctic and also occurs in South Georgia, and Kerguelen. Sinuber has two subspecies occurring around the continent and along the Scotia Arc, with a second species at Kerguelen. The genus Prolacuna is endemic to the Antarctic with four species. The monotypic endemic genus Frowina is known from the Davis Sea, while Tectonatica has two subspecies ranging from Magellan Strait to Paulet Island, on the Antarctic Peninsula.

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The great complex of forms usually classified in the two families Cominellidae and Buccinulidae, but rather doubtfully separable, supply the best example of explosive radiation in the Antarctic mollusca. The genus Pareuthria with many Subantarctic and southern South American species has one representative, P. innocens (Smith), widely distributed in East Antarctica. The genus Tromina has four species distributed in the Magellan region and on the Patagonian Shelf and one at the South Shetlands. The single species in the monotypic genus Falsimohnia, F. albozonata, has been recorded from Kerguelen and South Georgia. The genus Chlanidota provides an interesting example of specific radiation in itself (Fig. 11). Eight species are known, six of them confined to limited areas of the Scotia Arc and Bouvet Island respectively, one from East Antarctica, and one extending from Kerguelen to East Antarctica. The monotypic genus Chlanijicula is known only from East Antarctica while Notojicula, another monotypic genus is apparently circumAntarctic. The genus Pfevfferia with its three species is endemic to South Georgia. Chlanidotella with its single species C . modesta is confined also to South Georgia. The species Neobuccinum eatoni (Smith) is one of the most widely distributed Antarctic gastropods occurring right around the Continent, and at Kerguelen and Heard Islands. The genus Bathydomus is also an endemic genus, one of its four species being recorded from shallow water off Enderby Land, the other three from peripheral areas in depths from 2 515 to 3 423 m. Fusinella, another monotypic genus, is confined to Kerguelen Island, while the peculiar Cavineptunea is endemic to South Georgia. Probuccinum has seven Antarctic species and a single Subantarctic representative. Proneptunea occurs on Kerguelen (one species) and at South Georgia (two species). The genus which outweighs all the rest in numbers is Prosipho with 28 Antarctic and five subantarctic species. This latter genus produces several species which are coiled in a sinistral spiral in the normal condition. The family Muricidae has strong representation in the genus Trophon with large sized species in the Subantarctic and with a few exceptions smaller sized species in the Antarctic. The family Volutidae is at present known only by the genus Harpovoluta, an extremely thin-shelled form, with two species and subspecies from the Antarctic shelf. Two poorly known genera Guivillea and Provocator occur in adjoining deep-sea areas. Other volute genera are represented in deep-water collections made by the Eltanin. The genus Paradmete with four species confined to the AntarcticSubantarctic is the only member of the Volutomitridae.

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The Turridae is a family extremely well represented in deeper water.

It is hardly surprising therefore that this is also one of the important Antarctic families. Powell (1951, 1965) has illustrated the world distribution pattern for one of the most noteworthy Antarctic genera, Aforia. The Eltanin collections contain much more material of this genus, and also of other deeper water members of this family. Other turrids almost certainly of deep water origin are the three Antarctic species of Leucosyrinx, the four of Pleurotomella and one of Pontiothauma. Four endemic Antarctic genera are Belaturricula, Conorbela, Lorabela and Belalora, the first two confined to the Scotia Arc, the latter two extending to East Antarctica. The family Acteonidae supplies an interesting element to the gastropod fauna. The genus Acteon itself has one circum-Antarctic species, A . antarcticus Thiele. The two other genera occurring in the Antarctic are Neacteonina with two species and an additional one at Kerguelen, and Toledonia. This latter genus is widespread in Antarctic (five species) and Subantarctic (five species) waters. The systematics require revision and there are probably fewer species than those currently listed. One species or another supplies a characteristic element to most molluscan assemblages. Nudibranchs seem well adapted to the Antarctic-Subantarctic. Powell (1965) records 58 species arranged in 12 families and 28 genera. The family Charcotidae with two monotypic genera Charcotia and Telarma is endemic to the Antarctic as is the genus Notaeolidia with five species, the genus Azcstrodoris with five species in the Antarctic and several in the Subantarctic, and the monotypic genera Pseudotritonia and Guyvalvoria. The genus Bathydoris has five endemic Antarctic species, and there are many other species found exclusively in Antarctic waters. A more complete treatment of the gastropod fauna of both Antarctic and Subantarctic waters may be found in Powell (1960, 1965). 5 . Bivalvia (Fig. 12)

A full checklist of Antarctic and Subantarctic bivalves was given in Powell (1960). The same author (1965) has given a general account of the Antarctic bivalves. Other recent contributions to the group as a whole have come from Soot-Ryen (1951), the writer (Dell, 1964b) and Nicol ( 1966). Major points of interest only are given below. The family Nuculidae is one which could be expected to have established itself well in the Antarctic. To date only one species of Nuculu ( N . notobenthalis Thiele) has been described from 2 725 m in East Antarctica. The only other member of the family is Ennucula georgiana Dell endemic to South

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FIU.12. Some typicel Antarctic bivalves. A. Adamusaium colbecki (Smith) ;B. Limop8aa marionensis Smith ; C . Cuspidaria tenella Smith ; D. Thracia meridionah Smith ; E. Yoldia (Aequiyoldia) eightai (Couthouy, in Jay) ; F. Limatula hodgaoni Smith ; G. Laternula elliptica (King and Broderip) ; H. Cyclocardia astartoides (Martens).

Georgia, obviously derived from Magellanic forms. The family Nuculanidae, however, is well represented, as it is in the Arctic, with six genera. Four of the species are very characteristic Antarctic forms, Propeleda longicaudatu (Thiele), Yoldia (Aequiyoldia) eightsi (Coutheuy, in Jay), Silicula rouchi Lamy and Malletia Sabrina Hedley, while one or other of the species of Yoldiella is usually encountered in every area.

ANTAROTIC BENTHOS

!xJ

Some families only just gain entry into Antarctic faunal lists with either single species or singlegenera. The family Arcidae usually includes many medium sized species. The only Antarctic genus is the minute Bathyarca with two species in East Antarctica. The family of the mussels (Mytilidae)has only one genus (Dacrydium)with three minute, closely allied species in Antarctica. The enormous family of the Veneridae has a single representative of the genus Gomphina in the Scotia Arc while the Tellinidae has two species in the same area. Other families with only one species or at most one genus in the Antarctic are : Lyonsiidae, Pholadomyidae, Verticordiidae, and Poromyidae. Two other families in this category supply two of the most characteristic Antarctic bivalves. Thracia meridionalis Smith (Thraciidae) is a common species around the Continent extending through the Scotia Arc to the Falklands, and to the shelf areas surrounding Kerguelen, Marion and Prince Edward Islands. Laternula elliptica (King and Broderip), the sole representative of the Laternulidae is one of the most surprising Antarctic species. Species of the genus Laternula are distributed over a wide area of tropical and subtropical waters from the Red Sea to Japan and Australia. Two species reach Tasmania, the only other incursion by the genus into even cold-temperate waters. The essentially Northern Hemisphere family, Astartidae, has a pair of species in Antarctic-Subantarctic waters. Astarte longirostris Orbigny occurs off Kerguelen, Prince Edward and Marion Islands, the Magellan Region and South Georgia (Dell, 1964b)and has recently been recorded from East Antarctica (Nicol, 1966). The second species, A . antarctica Thiele occurs in East Antarctica. The family Carditidae has a single genus which extends into the Antarctic, Cyclocardia. There are several species in this genus in southern South America and two poorly understood forms, C. antarctica (Smith) and C. intermedia (Thiele),have been described from East Antarctica, in addition to the widely distributed species, C. astartoides (Martens). This latter is one of the commonest, and most widely distributed of Antarctic bivalves, occurring around the Continent, off Bouvet Island, through the Scotia Arc to South Georgia and into the Subantarctic at Kerguelen. The family Limopsidae supplies a very characteristic element to the bivalve fauna. The distribution of the Antarctic species of Limopsis has been detailed by the writer (Dell, 1964b, 1969), the very variable, most widely distributed species Limopsis marionensis Smith reaching a very large size for this genus, a specimen up to 80 mm in length having been reported by Powell (1958). The family Philobryidae is predominantly a southern family, with three Antarctic genera, Philobrya, Adacnarca and Lissarca. Probably

94

R. E. DELL

all species of these genera can attach themselves by byssal threads, and probably all brood the developing young inside the parent shells. The systematics of the genus Philobrya require critical revision based upon much better collections than have as yet been available. The writer (Dell, 1964b)has discussed some of the systematic problems, and pointed out probable synonyms. Species attach themselves to algae, hydroids or Bryozoa. The common widely distributed species is Philobrya sublaevis (Pelseneer). The small Adacnarca nitens Pelseneer attaches itself to hydroids, Bryozoa or sponges (Dell, 1964b), ascidians (Soot-Ryen, 1951), or gorgonaceans (Nicol, 1966). Mortensen (1909) reported it as attached to the spines of Notocidaris gaussensis Mortensen. A . nitens is circum-Antarctic in distribution, reaching South Georgia through the islands of the Scotia Arc. The genus Lissarca is well developed in the Subantarctic and farther north. The species, L. miliaris (Philippi) (which may include L . rubrofusca Smith) extends as far south as the South Shetland Islands. The typical Antarctic species, however, is L. notorcadensis Melvill and Standen which is circum-Antarctic in its distribution extending to South Georgia. This species is found attached to sponges, bryozoans, algae and hydroids, but usually to the spines of echinoids. The family Pectinidae is represented by three species of Cyclopecten and some badly-understood deep-water forms, and the large, circumAntarctic, brightly coloured Adamussium colbecki (Smith), which seems to occur most commonly in relatively shallow water. The genus contains only the single species and is endemic to the Antarctic. The family Limidae musters six species of Limatula, some not well understood. Three groups are obviously represented, the largest in size L. hodgsoni Smith, well distributed around the Antarctic and as far north as South Georgia. A group of medium-sized species centres round L. pygmea (Philippi) and L. ovalis (Thiele), and a small sized species is L. simillima (Thiele) which obviously belongs to the same group as the widely distributed L . subauricul ata . Several families of small bivalves are well represented, e.g. Cyamiidae, Thyasiridae, Leptonidae, Erycinidae, Montacutidae and Neoleptonidae. The family Gaimardiidae is essentially a Subantarctic, coldtemperate group, although a few species reach South Georgia. The septibranch genus Cuspidaria (Cuspidariidae) has five species, C. concentrica Thiele, C . infelix Thiele, C . plicata Thiele, C . kerguelensis (Smith) and C . tenella Smith in Antarctic waters. Nicol(l970) has summarized the major peculiarities of the Antarctic bivalves. A very high percentage (61%) are no more than 10 mm in length along their longest axis. Of the faunas analysed by Nicol the

ANTARCTIC BENTHOS

95

fauna with the next highest percentage of small forms is that of South Australia (38%). The percentage of infaunal species in the Antarctic is extremely low (59%) compared with the average (about 73%, as in the Arctic). Nicol (1964) pointed out that in common with the Arctic, no bivalves in Antarctic waters attach themselves to the substrate by cementing the shell to other solid objects. He also showed that this habit was extremely rare in abyssal mollusca, another essentially cold-water habitat. He could bring forward no completely satisfying explanation for this lack except that most cold-water bivalves have thin shells (in marked contrast to most forms which cement their shells to the bottom). In a further consideration of the characteristics of cold-water marine bivalves Nicol (1967) showed that representatives of this group shared a number of characters, whether arctic, antarctic, or abyssal molluscs were considered. Colour patterns are for example lacking in contrast to the common browns, reds, purples, and yellows of tropical waters. In the Antarctic the large thin-shelled pectinid Adamusium colbecki (Smith) is a purplish-red. The only other coloured bivalves Nicol knew from the Antarctic, Lasaea consanguinea (Smith) and Lissarca miliaris (Philippi), were mainly Subantarctic in distribution, reaching the Antarctic continent only along the Antarctic Peninsula. The shells of cold-water bivalves are generally thin, lacking spines or similar ornament, and the shell surface is often chalky. The growth rings on Antarctic bivalve shells are closely spaced indicating that growth is slow. Nicol believed that the cessation of growth probably did not result from seasonal temperature fluctuations but rather because of lack of phytoplankton during the winter months. A comparatively large number of Antarctic bivalves attach themselves to other organisms by means of a byssus. The attachment may be to sedentary plants and animals, such as algae, hydroids, other colonial coelenterates or Bryozoa, or even to the spines of echinoids. Such a habit may be of advantage for dispersal when fragments of the substrate are broken off to drift, but the success of forms with the habit of attachment in the Antarctic undoubtedly stems from the advantages gained by such species in obtaining adequate food. The plankton shower in the Antarctic forms the major source of food for sedentary animals and in the many areas where a dense deep growth of hydrozoans, bryozoans, sponges and gorgonaceans occurs the competition for the available food must be strong. Small bivalves would be at a distinct disadvantage in such an environment unless they could position themselves high in the canopy and maintain themselves there. For a bivalve

96

R. K. DELL

permanent attachment is about the only method available to achieve this end. 6. Molluscan Biogeography (Fig. 13)

The writer (Dell, 196413, 1969) was concerned to examine the Mollusca of that section of the Antarctic Continent which did not show

FIG.13. Distribution of some wide ranging Antarctic bivalves (data from Dell, 1969).

0 Adamusaium colbecki;

Cyclocardia asturtoides; [7 Limutula pygmum; Lhnatula hodgaoni; A G a a r c a notorcadem’e; A Philobrya ancblaevie; V T hracia meridio?adie; V Yoldia (Aequiyoldia) eightsi.

97

ANTAROTIC BENTHOS

immediate contact with South America through the Scotia Arc (a route by which it seems obvious that faunal elements are being added to Antarctica). The area comprising the Bellingshausen Sea, the Antarctic Peninsula and the Weddell Sea was therefore disregarded and attention was focused upon the molluscs of what is essentially East Antarctica. The benthic molluscs from this area comprise 309 species grouped in 154 genera and 91 families. Fifty of these families contain only one Antarctic species, and many are represented by minute, anomalous or deep-water genera only. Thus the Mytilidae contains only the small, deep-water genus, Dacrydium and the Arcidae only the small, deepwater, Bathyarca. Only five families contain more than 11 species (which is the average number for New Zealand). The restricted nature of the fauna may perhaps be best appreciated by comparing the number of families, genera and species of Antarctic mollusca with those from the Magellanic Region or with New Zealand and the same figures for bivalves alone from these areas and from the Panamic Region. Comparative figures for the faunas of East Antarctica, the Magellan Region and New Zealand (Dell, 1964b, 1969). TABLE IV

Benthic Molluaca East Antarctica Magellanic Region New Zealand Bivalves East Antarctica Magellanic Region New Zealand Panamic (Nicol, 1967)

Families

Genera

Species

91 114 160

154 280 552

309 667 1,759

25 39 44 46

36 89 142 147

66 175 400 555

These figures may be used to derive the average number of genera per family and the average number of species per family and per genus. It is thus obvious that the Antarctic molluscan fauna is an imbalanced one even compared with a small isolated biological entity like New Zealand. The writer (Dell, 1968) has presented the results of the analysis of the bathymetric distributions of 303 species of Antarctic mollusca for which reasonable data were available. Only 41 of these molluscs are confined to depths shallower than 180 m (a generous estimate for the

98

R. K. DELL

depth at which the outer limit of the shelf occurs elsewhere). Of these 41 species 22 have been found only in the area of the Antarctic Peninsula and the South Shetlands, the only area close to the continent where anything approaching a littoral fauna occurs. The proportion of Antarctic molluscs which can be considered exclusively shallow-water is remarkably low. Of the 303 species considered, no less than 130 species are confined to depths between 180 and 800 m and an additional 114 species span the depth of 180 m, occurring between some limit between 0 and 800m. This analysis shows the points often made concerning the Antarctic fauna. There is a very small element confined to shallow water. The archibenthal (or bathyal) fauna is extremely well represented (180-800 m). The element in the fauna which may be considered either as shelf species which have invaded the slope, or slope species which have invaded the shelf, is remarkably high. TABLEV Average genera per family Benthic Mollusca East Antarctica Magellan Region New Zealand Bivalves East Antarctica Magellan Region New Zealand Panamic Region (after Nicol, 1967)

Average ~peciea per family

3-4 5.8

Average 8PpeCie-9 per genus

1.7 2.5 3.4

11.0

2.0 2.4 3.2

1.4 2.3 3.2 3.2

2.6 4.5 9.9 12.1

1.8 2.0 2.8 3.8

A quite high percentage (39 out of 83) of the genera which occur in the deeper section of the shelf around Antarctica are genera which are represented in abyssal faunas elsewhere (Clarke, 1962). A high percentage of Antarctic Mollusca are probably circumAntarctic in high latitudes. For example, of the 75 species of bivalves, chitons and scaphopods, no less than 30 are now known from both East and West Antarctica. Some of the Mollusca besides being wide ranging seem to be fairly uniformly distributed, so much so that a range of the following may be expected in any dredge haul almost anywhere on the Antarctic shelf.

ANTARCTIC BENTHOS

99

Bivalvia Yoldia (Aequiyoldia)eightsi Propeleda longicaudata Silicula rouchi Malletia Sabrina Limopsis lilliei L. marionensis Philobrya sublaevis Adacnarca nitens Lissarca notorcadensis Adamussium colbecki Limatula hodgsoni Cyclocardia astartoides Pseudokellya cardiformis (Smith) Cyamiocardium denticulatum (Smith) Mysella miniuscula (Pfeffer) Thracia meridionalis Laternula elliptica Cuspidaria tenella Scaphopoda CaduEus dalli antarcticus Dentalium (Fissidentalium) majorinum Gastropoda Lepeta coppingeri (Smith) Capulua subcompressus Pelseneer Subonoba fraudulenta (Smith) Amauropsis (Kerguelenutica) grisea Neobuccinum eatoni Many other gastropods have a circumpolar distribution but do not seem t o be commonly encountered in any one area. In some genera there are a range of closely allied species and one or other species of Prosipho , Cerithiopsilla , Margar ella, Ovirissoa , Subonova, A mauropsis , Trophon and Toledonia are likely to occur in most assemblages. The writer (Dell, 1968) has commented on the number of Antarctic shelf Mollusca which have wide bathymetric ranges, a total of 48 species having ranges greater than 500 m, five with ranges greater than 1 000m. With a few exceptions these species with wide bathymetric ranges include those which make up the most widespread, commonly en-

100

R. K. DELL

countered, elements of the Antarctic molluscan fauna. Examples of some of these bathymetric ranges are :

Silicula rouchi ( 1 6 6 8 3 6 m) PropeZeda longicaudata ( 6 P 1 080 m) Yoldia (Aequiyoldia) eightsi (5-728 m) Limopsis marionensis ( 1 4 6 914 m) Philobrya subZaevis (8-860 m) Adacnurca nitens (8-1 080 m) Lissarca notorcadensis (18-720 m) Adamussium colbecki ( P 1 335 m) Cyamiocardium denticulatum (23-757 m) Limatula hodgsoni (12-695 m) Cyclocardia astartoides (15-836 m) Thracia meridionalis (5-752 m) Cadulus dalli antarctica (43-836 m) Margarella refulgens (Smith) (1-720 m) Lepeta coppingeri (18-860 m) Trichoconcha mirabilis Smith (122-900 m) Trophon longstafl Smith (15-720 m) Toledonia hedleyi Powell (45-640 m) 7. Temperature tolerances of some Antarctic Mollusca Some years ago the writer determined the ranges of bottom temperatures at which some Antarctic molluscs were obviously able t o live. Based mainly upon collections from stations established by the Discovery Investigations, and using the associated hydrographic station data. These ranges cannot be taken to be complete but they do span the extremes of the known ranges in most cases. Only a few of these figures have been published previously (Dell, 1968). As might be expected some of the species which, although they are widespread in Antarctic waters, also extend widely into the Subantarctic, and in some cases into the cold temperate of southern South America, show wide temperature tolerances, e.g. :

Lepidopleurus kerguelensis ( -0.42-8.30"C) ; Dentalium (Fissidentalium)majorinum ( -0-56-6.19°c) Yoldia (Aequiyoldia)eightsi ( -O.5O-7.6O0C) ; Limopsis marionensis ( -0~56-6~10"C); Cyamiocardium denticulatum (- 1.90-8-1 8OC) ; Cyamiomactra laminifera (Lamyj ( -0.24-5-14"C) ; Thrucia meridionalis (- 1.90-5-34"C).

;

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ANTAROTIC BENTHOS

It would be expected that the Antarctic fauna should contain a high percentage of cold-water stenothermal species. The best marked of these on the present data are as follows (known temperature ranges in parentheses) : Cadulus ( P . ) dalli antarcticus (-0.66-2.08"C); Propeleda longicauduta (-0.66-2.08OC); Silicula rouchi (-0m-0.40"C); Limopsis lilliei (-0-66-2.08"C); Philobrya sublaeuis ( -1.90-2.08"C); Adacnarm nitens ( -1.90-1.42°C); Lissarca notorcadensis ( -1.66-2.08"C); Limatula hodgsoni (-1-66-2.08"C); Pseudokellya cardifomis ( -0.66-1.37°C); Cyclomrdia aatartoides (- 1.90-2.08°C); Cuspidaria tenella ( -0.42-0*76"C); Cuspidaria infelix (-0.66-2.08"C). The ranges for a number of forms which do not reach the Antarctic Continent may be considered for comparison. Limopsis scotiana Dell, apparently confined to South Georgia, the South Orkneys and the South Shetlands, has a very restricted range from -0.48 to 1~32°C. There thus seems no reason why it could not invade Antarctic waters from temperature considerations alone. Limopsis Airtella Rochebrune and Mabille, found in southern South America and the Falklands, has a range largely confined to water from 4.32 to 8.18"C while Astarte longirostri8, from the Subantarctic and South Georgia, ranges from about 4.91 to 8.30"C. 8. The Scotia Arc as a migration route The only shallow water migration route between any other shallowwater area and the Antarctic continental shelf is through the scattered island groups and associated shelves of the Scotia Arc. The arc is bent right back on itself, the island groups comprising it are relatively widely spaced, and the major hydrological phenomenon of the Southern Ocean, the Antarctic Convergence, cuts across it. This is not to be considered a broad highway through which whole faunas can automatically migrate. It presents a series of gaps which by combinations of barriers of various kinds filter out families, genera and speaies selectively preventing some from reaching Antarctica, and in turn preventing some Antarctic forms from reaching South America. Consideration of the extent to which some molluscan families penetrate the Scotia Arc shows this selective action. A large number A.X.B.-lO

b

102

R. R. DELL

of families extend no farther south than the Falklands and the southern tip of South America, e.g. Chitonidae, Acanthochitonidae, Anomiidae, Cardiidae, Mactridae, Condylocardiidae, Lucinidae, Solenidae, Corbulidae, Myidae, Pandoridae, Teredinidae, Acmaeidae and Nassariidae. Another family, the Olividae, reaches the Burdwood Bank. South Georgia is the limit for the Veneridae, Tellinidae, Hiatellidae, Calyptraeidae and Retusidae. The chiton family Chaetopleuridae does not extend farther than the South Orkneys. Five more families have established themselves on the Antarctic Peninsula or the two seas of West Antarctica, i.e. Hanleyidae, Ischnochitonidae, Mopaliidae, Gaimardiidae and Patellidae (Dell, 1964b, 1969). There seems no doubt that Mollusca have also achieved dispersal in the reverse direction, widely distributed Antarctic species reaching different northern limits along the Arc. Some species such as Cadulus dalli antarcticus are conhed to the continent, the South Shetlands, South Orkneys and South Sandwich Islands. A very large group reaches as far north as South Georgia, e.g. Adacnarca, Pseudokellya, Propeleda, L-imatula hodgsoni, Limqsis lilliei, Philobrya sublaevis, Lissarca notorcadensis, Cyclocardia astartoides, Laternula elliptica, Cuspidaria infelix and C . tenella. Some Antarctic species reach the Falkland Islands but do not occur on the mainland of South America, e.g. Cyamiomactra laminifera and Thracia meridionalis. Four other Antarctic species which reach their northern limit here have not as yet been recorded from South Georgia and may be presumed to have crossed the Drake Passage more directly, Nuttalochiton mirandus, Dentalium majorinum, Limopsis marionensis and Cyamiocardium denticdatum (although the last three species also reach southern South America). Several Antarctic species extend t o the South America mainland, Yoldia (Aequiyoldia) eightsi, Lepidopleurus kerguelensis, Callochiton T ~ LVI E

Total number of species South Georgia South Orkneys South Sandwich Islands South Shetlrtnds Antarctic Peninsula Bouvet Island

47 29 10 29

31 8

Percentage of Eaat Antarctic forms

(%) 42 48 90

68 71 82

ANTARCTIO BENTHOS

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gaussi, and Dentalium (Fissidentalium)majorinum reaching their limits about the northern shores of Magellan Strait, while Cyamiocardium and Limopsis marionensis reach to about 40"s on the west coast. An analysis of the bivalves and scaphopods of East Antarctica which also occur in parts of West Antarctica and the island groups of the Scotia Arc, gives supporting evidence for these latter to be considered a series of stepping stones (Table VI). 9. The origins of the Antarctic Mollusca

Three faunal elements are obvious amongst the Mollusca of the Antarctic 1 1. forms with deep-water affinities; 2. forms which show evidence of derivation from South America

through the Scotia Arc; 3. genera and species which have no obvious immediate affinity,

and which appear to be an

"

old " Antarctic element.

1. Genera which appear to be deep-water derivatives include the nuculids and nuculanids, although the genus Propeleda and the subgenus Aequiyoldia seem to be local Antarctic evolutionary products. Propeleda is very close to Nuculana (s. str) and is probably derived from this genus. Malletia, Bathyarca, Limopsis, Dacrydium, Cyclopecten, Limatula, Thyasira, Lyonsia, Plwladomya, Thracia, Lyonsiella, Poromya and Cuspidaria are all bivalves well represented in deep water elsewhere. Burne (1920) noted that Limatula hodgsoni has some less specialized and apparently more primitive anatomical features amongst the Limidae, but the anatomy of too few forms is known for too much weight to be placed on this evidence. But because bivalves are placed in this category does not mean that they are not at the same time " old " inhabitants of Antarctica. Amongst the gastropods with fairly obviously deep-water afinity are the turrids Aforia, Leucosyrinx, Pleurotomella and Pontiothauma, and the limpets Puncturella and Lepeta. 2. Apart from forms which have not as yet penetrated any farther into the Antarctic than various island groups of the Scotia Arc, the Antarctic Peninsula or the other areas of West Antarctica, there is an element of the widespread Antarctic fauna which appears to have been derived through this migration route a t an earlier period. Genera concerned would include Nuttalochiton, Philobrya, Astarte and Cyclocardia. 3. Soot-Ryen (1961) discussed an " old " Antarctic fauna as, " the remains of an earlier Antarctic fauna with ancestors from a time of more genial climatic conditions ". Such genera and species as follows seem

104

R. K. DELL

to belong in this group: Adamwsium colbecki, Adacnarca, Laternula, Ptycbcardia, Cyamiocurdium, Pseudokellya, Dentalium (Pissidentalium) majorinum, Cadulus dalli antarcticus, and possibly Limatula bdgsoni, Thracia meridionalis, Limopsis marionensis and Cyclocardia aetartoides. Amongst the gastropods this group probably includes Submargarita, Antimurgarita, Falsimargarita, Cerithiqsilla, Chlanidota, Neobuccinum and Prosipb as well as the series of trichotropid genera Antitrichotropis, Trichoconcha, Neoconcha and Discotrichoconcha. This latter group, obviously representing another example of explosive adaptation as does the plethora of Antarctic genera of buccinacean origin, must surely have had an earlier derivation. The genus Laternula, represented by the widely distributed L. elliptica, in the Antarctic and Subantarctic, a large thin-shelled bivalve genus, is otherwise found only in the tropical Indo-Pacific with one species in southern Australia and Tasmania, but lacking any other representation in South Africa or New Zealand or in South America (Soot-Ryen, 1951; Powell, 1965). 10. South Ueorgia The Mollusca of South Georgia mirror the faunal mixture seen in so many other groups. Some 164 species of benthic Mollusca have been recorded from South Georgia, of which 98 species are found nowhere else. This high endemic element may be more apparent than real when careful comparisons can be made between the total South Georgian molluscan fauna and that of the other islands of the Scotia Arc. Many of the shallow-water South Georgian forms described by Martens and Pfeffer (1886) must be assessed in the light of modern systematic practice, and with adequate new collections. However, even if the percentage of apparent endemism is lowered, to some extent, there will still be a strong unique element. The presence of a number of endemic genera of gastropods adds to this distinctive character, e.g. Promargarita, Pfefferia, Chlanidotella and Cauineptunea. At the same time for Mollusca as for most other groups South Georgia acts as a staging area on the migration route from South America through the Scotia Arc to Antarctica, and similarly in the reverse direction.

Q. Echinodermata 1. Echinoidea

Apart from some general papers on echinoderms our main knowledge of the Antarctic echinoids has come from papers by Koehler 1926), Bernasconi (1953) and particularly by Mortensen (1909, 1910, 1928, 1950a, 1961). Pawson (1969b) has given a review and illustrations of distribution patterns.

ANTARCTIC BENTHOS

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The most marked feature of the composition of the Antarctic echinoid fauna is the very sparse family representation. Over 60 families of echinoids are known. Of these only six families occur in the coastal waters of Antarctica. The super-orders Diadematacea and Gnathostomata are absent and the only representative of the super-order Echinacea is the genus Sterechinus. On the positive side the cidaroid subfamily Ctenocidaridae and the spatangid family Schizasteridae are extremely well represented with every indication of radiative evolution. The subfamily Ctenocidarinae is apparently an ancient group which developed in Antarctica and has remained almost completely confined to the Antarctic-Subantarctic area (Mortensen, 1928). Mortensen has reported an Eocene species of Austrocidaris from Patagonia. The members of this subfamily with a precis of their distribution are given below. 1. Notocidaris. A genus endemic to the Antarctic, and there represented by six species, N . gaussensis Mortensen, N . hastata Mortensen, N . mortenseni Koehler, N . platyacanth (H. L. Clark), N . remigera Mortensen and N . spinosa Koehler. Distribution maps show four centres of distribution, but these are the usual ones which show up on Antarctic distribution maps and can only be said to map expeditionary effort. The species seem largely confined to the Antarctic shelf'. N . gaussensis broods its young. 2. Ctenociduris. Known only from the Antarctic-Subantarctic, with six species. The species C. geliberti (Koehler), C . perrieri Koehler, C . polyplax Mortensen, C. speciosa Mortensen and C. rugosa (Koehler) are confined to the Antarctic, while C. nutrix (Thomson) is known from around Kerguelen and off the Crozets. Ctenociduris speciosa is found on the Antarctic continental shelf' but also extends to South Georgia, the only representative of the subfamily so far recorded from this latter locality. 3. Aporocidaris. Two species occur in the Antarctic, one A . incerta Koehler apparently confined to this area, the other A . untarctica Mortensen occurring off East Antarctica and also off the Crozets. The two other known species occur off the Galapagos ( A . milleri (Agassia)) and from the North Pacific ( A .fragilis (Agassiz and Clark)), both in depths over 2 800 m. 4. Bhynchocidaris. The sole species in this endemic genus, R. triplopora Mortensen has been recorded from East Antarctica and from off the Antarctic Peninsula. 6 . Hornabcidaris. Another endemic Antarctic genus based upon the sole species, H . gigantea (H. L. Clark), known only from off East Antarctica.

106

R . K. DELL

6. Austrocidaris. The two species, A . canaliculata (Agassiz) and A. spinulosa Mortensen are confined to Southern South America, the Patagonian shelf and the Falkland Islands. 7. Ogmocidaris. Another monotypic genus, with 0. benhami Mortensen being confined to the New Zealand region. Thus of the seven genera and 21 species, five genera and 16 species are found in Antarctica (three genera and 14 species being found nowhere else). The genus Sterechinus, the only regular non-cidaroid sea urchin genus in the Antarctic, has five species. One, S. diadema (Studer) is known only from Kerguelen Island, one S. ugassizi Mortensen seems to be centred in southern South America although it also occurs in South Georgia. The other three species,S.neumayeri (Meissner),S. antarcticus Koehler and S. dentifer Koehler, are found around the Continent with S . neumayeri obviously circum-Antarctic and extending to the South Orknep and South Georgia. The name Sterechinus neumayeri crops up again and again in the more recently published accounts of diving investigations in shallow water from the islands of the Scotia Arc to the Ross Sea. Pearse and Giese (1966) studied the food, reproduction and organic constitution of this species in McMurdo Sound. Here S. neumayeri occurred abundantly on basaltic gravel at less than 15 m depth. Like many other regular echinoids, these sea urchins often cover their tests with stones and whatever other debris is available. I n some areas in McMurdo Sound the echinoid occurred together with abundant red algae (Iridaea sp.). However, the main food from about November to April seems to be diatoms, an extensive layer of which appears on the sea, floor in shallow water over this period. In areas near extensive concentrations of Weddell seals, the sea floor becomes littered with seal faeces. Sterechinus gathers round these deposits in these areas, and Pearse and Giese found the gut then filled with seal faeces with comparatively few diatoms. This species of echinoid is obviously another of the successful, widely distributed Antarctic animals whose lack of adaptation to narrow feeding requirements has undoubtedly contributed to their ecological success. Pearse and Giese give a full account of gonad development and oocyte generations, but were not able to study development after fertilization. The beginning of growth of the oocytes of Sterechinus probably takes place between November and May, during the period of production of phytoplankton. Gonads grow throughout the summer, in part through the accumulation of food materials in the nutritive phagocytes of the

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gonads. Spawning takes place in the southern winter, somewhere between May and December. The ova are of relatively small size (about 125 p) and this suggests indirect development. From the evidence of echinoplutei collected on earlier expeditions, and almost certainly belonging to this species, Sterechinw probably develops feeding echinopluteus larvae during the summer. Plankton samples taken throughout the year a t McMurdo Sound failed to produce any echinoplutei. From the available evidence it appears that oocytes take from 18 to 24 months to reach maturity, spawning occurs in winter between May and December and that early embryonic development is slow, so that echinopluteus larvae are finally produced in the summer, when maximum plant food is available. The larval habitat is presumed to be close to the bottom. Members of the family Schizasteridae comprise some of the most typical Antarctic animals. The genus Abatus with ten species is confined to the Antarctic and Subantarctic with an incursion into the coastal waters of Argentina. One species A. cordatus (Verrill) has been recorded only from the vicinity of Kerguelen and Heard Island. Three species, A . agassizi (Pfeffer), A. cavernosus (Philippi) and A . philippi L o v h have been recorded from East Antarctica, the Antarctic Peninsula (except for agussizi),south Georgia and Southern South America, with A . cavernosus and A . philippi extending to about 36'5. Two species have a restricted distribution in West Antarctica, with A. elongatus (Koehler) confined to the South Orkneys and A . curvidens Mortensen known only from the Antarctic Peninsula. Two species, A. nimrodiuna (Koehler) and A. ingens Koehler are known only from East Antarctica while A . shackletoni Koehler and A . bidens Mortensen appear to be circum-Antarctic. It seems probable that most (if not all) of the species of Abatus brood their young in the sunken dorsal petals of the female. This habit has been recorded for A . nimrodi, A. shackletoni and A . bidens (Amaud, 1964) and A. ingelzs (Koehler, 1926).

All records for species of this genus appear to be from depths less than 700 m. If the habit of larval brooding has always been part of the generic makeup, the dispersal mechanism must have been slow along comparatively shallow water shelves. Given time (and this seems to have been abundantly available for Abatus) this seems to have been no barrier to dispersal. The genus Amphipneustes is even more strictly Antarctic than Abatus. One species A. koehleri Mortensen occurs off South Georgia and Shag Rocks. A. sirnilis Mortensen occurs off the Antarctic Peninsula and off the South Orkneys. The other species are all confined to the

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shelf of the continent, A . lorioli Koehler possibly being circum-Antarctic, but all the other species, A . bisdus Mortensen, A . brevisternulis (Koehler), A . marsupialis (Koehler), A . rostratus (Koehler) and A . tumescens (Koehler) are on the present evidence known only from East Antarctica. Species of the genus are known from 0 to 645 m, but most live deeper than 100 m. Tripylus has two species represented off the Antarctic Peninsula, T.cordatus (Koehler) and T. reductus Koehler. This latter species together with a third, T . excavatus Philippi, also occurs in southern South America. Tripplaster is represented by T . philippi (Gray) which is distributed off both coasts of southern South America and also reaches South Georgia. Two other families of spatangid echinoids are known from Antarctio waters, the Urechinidae and the Pourtalesiidae. Both are essentially deep-sea forms with wide distribution in the ocean basins. The family Urechinidae has three genera in the Antarctio Urechinus, Pilematechinus and Plexechinus. Urechinus drygalskii Mortensen was described from 3 423 m near the Antarctic Continent. Pilematechinm veeica (Agassiz) has a very thin test which collapses when the animal is removed from water (Mortensen, 1950a). It has been collected from off Chile and from 6.5'42'5 79'49'E in Antarctic waters. The genus is characteristic of depths from about 2 000 to 4 000 m, P . vesica being recorded from 3 060 to 4 030 m (Mortensen, 1950). Plexechinus nordenskjoldia Mortensen is known from off South Georgia and the Antarctic Continent in d e p t h from 110 to 300 m. This is the shallowest record for any representative of the family. The other unusual feature is that it is the only member of the family which is apparently brood protecting (Mortensen, 1950). The family Pourtalesiidae comprises another group of deep-sea, forms, none of which is known to be brood protecting. Three species are recorded from Antarctic waters, Pourtalesia hispida Agassiz from 1 690 to 3 610 m, P . aurorae Koehler from about 440 to 1 690 m and P. debilis Koehler from 455 m at 64'44'S 97'28'E. Pifteen genera of echinoids are recorded from south of the Antarctic Convergence, four restricted to the area, with another six endemic to the Antarctic-Subantarctic region. Thus 25% of the echinoid genera are endemic, though 66% of the genera are endemic to the AntarcticSubantarctic. Some 44 species are known from the Antarctic shelf, of which 77% are endemic (34 species). Of these species the major part (28 species) are classified in five genera.

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2. Asteroidea

Work on Antarctic asteroids has been dominated by two workers, Koehler, particularly in his paper (1920) on the Australian Antarctic Expedition, and W. K. Fisher in his Discovery Report (1940). Dr A. M. Clark (1962) added significantly to our knowledge with her work on the B.A.N.Z.A.R. Expedition and Dr H. S. Clark (1963) described the material collected in the Ross Sea. Fell and Dawsey (1969) have recently shown the distribution of 42 genera and 166 species out of the known asteroid fauna south of 35'5 (excluding Australasia) of 87 genera and 232 species. All Antarctic genera were included except for those with spotty (and hence relatively poorly documented) distribution patterns and for those of universal deep-water distribution. They discerned three conspicuous distribution patterns. 1. Circumpolar, chiefly around Antarctica, but usually including South Georgia. 2. Circumpolar in the Antarctic generally, including the Magellanic region. 3. Circumpolar or incompletely circumpolar in the Subantarctic. The following genera are endemic to the Antarctic (Fisher, 1940) : Mimastrella, Acodontaster, Notioceramus, Pergamaster, Chitonaster, Scotiaster, Kampylaster, Mirastrella, Rhopiella, Paralophmter, Myoraster, Cuenotaster, Odinella, Belgicella, Notasterias, Lysasterias, Saliasterias and Granaster. Fisher also gives a useful list of species which give " character " to the Antarctic fauna either because they are large or occur frequently. Exceptionally large species are : Leptychaster accrescens (Koehler), L. jiexuosa (Koehler), L. magni$cus (Koehler), Bathybiaster loripes obesue Sladen, Psilaster charcoti (Koehler), Luidiaster gerlachei (Ludwig), Acodontaster elongatus (Sladen), A . conspicuus (Koehler), A. hdgsoni (Bell), Perknaster fuscus antarcticus (Koehler), P.charcoti (Koehler), P. aurorae (Koehler), Myoraster antarcticus (Koehler), Labidiaster annulatus Sladen, Lysasterias perrieri (Studer), and Diplasterias brucei (Koehler). The species which are frequently encountered in numbers include : Bathybiaster loripes obesus, Psilaster charcoti, Odontaster meridionalis (Smith), 0. validus Koehler, Perknaster fuscus antarcticus, Porania antarctica glabra Fisher, Myoraster antarcticus, Labidiaster annulatus, Lysasterias perrieri, Diplasterias brucei and Granaster nutrix (Studer). Clark (1963) found that the distribution of asteroids in the islands of the Scotia Arc was similar to that sketched for ophiuroids by Fell (1961) and that the gap between South Georgia and the Falklands was a faunal

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gap dividing what was called ‘r strictly Antarctic ” from “ a peripheral Antarctic fauna ”. Genera characteristic of the Antarctic fauna are Macroptychaster, Bathybiaster, Psilaster, Luidiaster, Kampylaster, Myoraster, Cuenotaster, Notasterias and Lysasterias (Clark, 1963). Two genera of asteroids otherwise confined to Antarctica extend to southern South America, i.e. Perknaster and Acodontaster (Clark, 1963). Fisher (1940)gave an extremely useful list of Antarctic seastars together with their known bathymetric range. This list totalled 114 species arranged in 50 genera. Clark (1963,p. 79)recorded that of the 37 species from the Ross Sea, only 13 extended into the Subantarctic or south temperate zones. It is not clear from Clark’s rather brief remarks whether these extensions take place to the north of the Ross Sea or through the Scotia Arc, though it is implied that more are via the latter route. Dawson (1970) shows that only one of the species of Asteroidea found in the Ross SeaBalleny Island region is also found at Macquarie, and that none of them also occur in New Zealand. Bernasconi (1970)recorded 32 species grouped in 8 families and 19 genera collected by the Argentinean Antarctic expeditions to the Antarctic Peninsula. Some 6 species previously known only from East Antarctica were shown t o occur also in West Antarctica. A general account of the brooding habit in echinoderms is given in a separate section. A peculiar adaptation exists in the asteroid Odinella nutrix Fisher (family Brisingidae) described by Fisher (1940). Here special brood chambers form in the interradius with permanent spine bridges forming a basket. Some five to nine eggs are deposited in the basket, and the developing young are kept there. Usually two or three young are much more advanced than the rest. Some few individual Antarctic benthic species have now received intensive study. Such a one is the seastar, Odontaster validus Koehler. First described in 1906 it has been collected, often in large numbers, by most subsequent Antarctic expeditions. Apart from its systematic position and general anatomy, however, most of what we now know of its biology is due to the work of a “ resident ” marine biologist, J. S. Pearse, working at the USARP Laboratory a t McMurdo Sound. I n a series of papers he has discussed reproductive periodicities in contrasting populations (1965,1966) and its general larval development (19694. I n a semi-popular account he has presented a summary of his findings (1969b) in a form which makes them readily intelligible to a nonspecialist reader.

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Odontaster validus in the McMurdo Sound area occurs mainly down to about 60 m. From the shore down to about 20 m the bottom consists of basaltic gravel and boulders and life is relatively sparse, largely no doubt due to the unstable conditions. The area is subject to large amounts of fresh water from melting snow and ice during the summer while during the winter the bottom is scoured by ice-floes. Anchor ice also forms on the bottom and floats to the undersurface of the floating sea ice in the early summer. Odontaster has been shown to be able to survive in much diluted sea water. I n general it has obviously been able t o adapt to these d s c u l t conditions and often occurs in large numbers. It appears to be largely omnivorous, feeding normally on bottom detritus. Specimens are attracted to seal, beef or fish meat in traps and they have been observed feeding on sea urchins, amphipods and euphausiids and even seal faeces. The stomachs examined normally contain detritus and small invertebrates. The main digestive and nutrient storage organs of seastars such as Odontaster are the pyloric caeca. Pearse showed that measured by dry weight, pyloric caecal lipid ranged from about 15 to 25%, and carbohydrate from about 2 to 12%. Pearse observed that in areas of high plant production the pyloric caeca nearly doubled their weight in the summer and the carbohydrate content mainly in the form of poly. saccharides increased by nearly 500%. A marked decrease took place after diatom production ceased. I n areas where the summer benthic diatom production was low animals tended to be pale coloured, whereas they were deep red or orange in areas where diatom concentrations were high. Since Odontaeter has never been collected from beneath the permanent ice cover of the Ross Ice Shelf, Pearse supposes that some plant food may be necessary for this species. A large part of Pearse’s work on Odontaster was concerned with reproduction and development. Sexes in this species are separate. Spawning occurs only during the winter months (in McMurdo Sound between late May and mid-September). The gonads gradually reduce in size so that it would appear that eggs or sperm are released gradually over a period. The development of gametes is slow, developing eggs or sperm remaining in the adult for up to two years, although release is annual. I n adult females up to three separate size classes of eggs are present, representing eggs to be released in three separate years. The actual number of gametes produced is related to the food supply, but the stage of gamete production and the spawning time seems to be essentially the same in all the localities examined in the Ross Sea and even beyond. Since there are marked differences between the amount of light and temperatures between these localities it seems that

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neither of these factors is the regulating one. Pearse supposes that the period of phytoplankton production (the onset of which is fairly sudden and uniform throughout) may be the controlling factor. Eggs and sperm at spawning time are shed into the sea water where fertilization occurs. Early development of the fertilized embryo follows the usual pattern for starfish with indirect development through a blastula, a gastrula and then to the typical bipinnaria. Development has not been traced beyond this stage. Up to the bipinnaria development is remarkably slow but this results in the main feeding stage occurring when diatom food is available. All the evidence points to the fact that, unlike most other seastar larvae known, the developing stages of Odontaster swim close to the bottom. No larval stages have been collected from the plankton. Such a habit with the larval stages keeping near the bottom represents in Pearse’s opinion a aompromise allowing efficient dispersal without exposing the larvae to the hazardous conditions in the plankton. Growth appears to be very slow throughout its life. Pearse shows that growth may take place a t a rate of only a few grammes a year, that they do not begin t o spawn until they are between three and six years old, and that large specimens of about 100 g weight may well be between 60 and 100 years old and perhaps even older. Pearse found 0. validus to be remarkably free of predators and commensals and believes this species to be near a top trophic level in this environment, with population regulation coming in part through the effect of available food supply and production of gametes. A. M. Clark (1962) has given keys to orders, families, genera and species of Southern Ocean seastars. 3. Ophiuroidea

Knowledge of the Antarctic brittle stars has been derived mainly from the work of Koehler (in a series of papers 1901-23), Hertz (1926), Mortensen (1937), Fell (1961) and Madsen (1967). McKnight (1967) and Sen0 and Irimura (1968) have recently described a new species each from the Ross Sea, while Arnaud (1964) has given much information on the occurrence of the group in relatively shallow water off Adelie Land. Ophiuroids are one of the commonest groups represented in the Antarctic benthic fauna. I n places in the Ross Sea they may form onethird the total biomass (Fell, 1961). Calculations based upon bottom photographs between 75 and 350 m, show that in local concentrations ophiuroids may be aa plentiful as 10000000/km2. Ophiacizntha

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antarctica Koehler was recognized by Fell (1961) as being the most abundant and widely distributed echinoderm in the Ross Sea. East Antarctica has a fauna of 23 genera and 38 species of ophiuroids, of which 78% of the genera and 47% of the species are also found in the Antarctic Peninsula and South Georgia. Of the 31 genera and 62 species found in the Antarctic Peninsula and South Georgia, 45% of the genera and 25% of the species are found on the Falkland Islands and Patagonian Shelf (Yell et al., 1969). Some genera, e.g. Euvondrea and Glaciacantha are so far known only from the Ross Sea. The genus Ophiosteira seems to be very well developed in the Ross Sea, absent from the Bellingshausen Sea. Generally the Ross Sea shares at least half its species of ophiuroids with West Antarctica. The Antarctic ophiuroid fauna is distinguished by the stenothermal genera, Astrohamma, Astrochlamys, Glaciacantha, Ophiosparte, Ophiodaces, Euvondrea, Ophioperla and Theodoria (Fell, 1961). Some more eurythermal genera which appear basically Antarctic in distribution extend to southern South America, e.g. Astrotoma, Ophiuroglypha and Ophiurolepis. Fell (1961) considered that most Antarctic echinoderms would not be distributed by planktonic larvae. Viviparity and direct development are very common amongst Antarctic echinoderms, particularly the ophiuroids. Even in those echinoderms which possess planktonic larvae, the larval life is so short that long distance dispersal would not be possible. The happy conjunction of good trawl collections from the Ross Sea together with an excellent series of photographs of the sea bottom taken by J. S. Bullivant, in the same areas as the biological stations, allowed Dr H. B. Fell to trace the feeding habits and some general ecology for several ophiuroids. The peculiar Astrotoma agassizii Lyman was traced on one photograph with the arms rolled inwards, indicating that this species probably sits on the bottom with the oral surface uppermost, using the long arms to sweep the water and capture pelagic organisms as suggested by Mortensen (1937). I n some photographs Amphiura belgicae Koehler, Ophiurolepis gelida (Koehler) and a species believed to be Ophiacantha pentactis Mortensen could all be recognized. Amphiura belgicae was common resting on bryozoans with the arms outspread, and may have been feeding on the zooids of the bryozoans, or both species may have been feeding on the plankton shower. Ophiurolepis gelida is nearly always infected with a parasitic sponge, Oophon radiatus Topsent, and specimens with this sponge attached

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were easily identified in the bottom photographs. Ophiurolepis was also crawling over bryozoan colonies in company with Amphiura belgicae. Ophiurolepis also occurs quite commonly on soft bottom sediments. I n a series of photographs, Fell recognized Ophioceres incipiens Koehler by means of a number of characters and realized that this species ‘‘ fished ” the water for falling particles of food by attaching itself by two arms to tube worms, colonial hydroids or sponges and spreading the other three into the water. The female ophiuroid Astrochlamys bruneus Koehler has the habit of carrying dwarf males on her back (Mortensen, 1937). Fell (1961) recorded two small males clinging to the dorsal surface of a female. 4. Crinoidea

Dearborn and Rommel (1969) summarized knowledge of the group in the Antarctic. Of the 23 families of living crinoids, only two, the Notocrinidae and the Antedonidae occur on the Antarctic Shelf and the shelves of the outlying islands of South Georgia, Bouvet, Heard, Kerguelen, Prince Edward, the Crozets and Gough Island. One family, the Notocrinidae, having a peculiarly modified reproductive system, is endemic to this area. The crinoids of this shelf area are all comatulids. I n abyssal depths contiguous to the Antarctic and Subantarctic additional families such as the Bathycrinidae, Hyocrinidae, Thalassometridae and Pentametrocrinidae occur. Four species of stalked crinoids are known from the area considered Antarctic in the present study. Bathycrinus australis A. H. Clark ranges from 2 514 to 4 636 m. The other three species belong to the family Hyocrinidae. Ptilocrinus brucei Vaney has been collected between 3 245 and 4 973 m, P. antarcticus Bather from about 480 m, and Hyocrinus bethelzianus Wyville Thomaon known from 2 926 to 4 636 m. As with some other echinoderm groups, e.g. the holothurians, a vast amount of recently collected material which is still being studied is not yet available for distributional records, Only five species are as yet recorded from 10 or more occurrences. Many are known from only L few specimens and because of their delicate nature even these may be in bad condition. The peculiar family Notocrinidae contains only two known species, Notocrinus mortenseni John (known from depths from 194 to 603 m) and N . virilis Mortensen (from 163 to 649 m). I n this genus, and hence in the family, the gonads are found in the axils between the pinnules and the arms (a unique position in crinoids), with the testes about twice the

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size of the ovaries. Both species occur in both East and West Antarctica and are probably circumpolar. The remaining shelf crinoids all belong to the family Antedonidae. Promachocrinus kerguelensis Carpenter is the most abundant crinoid in the Antarctic. Ranging from depths from 10 to 1 080 m, it occurs right around the Continent and through the Scotia Arc. Other relatively common species which have a circum-Antarctic distribution are : Florometra mawsoni A. H. Clark (100-917 m), and Anthometra adriani (Bell) (189-917 m). Isometra vivipara Mortensen although it has been collected frequently seems to be confined to the Antarctic Peninsula, the Falkland Islands and southern South America in depths from 79 to 350 m. Isometra graminea John (194-567 m) seems to be the only species of Isometra with a circumpolar distribution, Isometra hordea John having been recorded from several stations along the Scotia Arc and 1. fktvescens John only from Shag Rocks. Most of the other Antarctic shelf crinoids have a very restricted range. These are listed by Dearborn and Rommel (1969, p. 35). 6 . Holothuroidea

There has been little recent work on Antarctic holothurians. Pawson gave a summary of the group for the Antarctic Map Folio Series (1969) but the last published work was Ekman’s definitive paper (1926). Previous work on the group had been contributed by Perrier (1905) and Vaney (1906a,b,c, 1909, 1914). Pawson did not consider the deep-sea order Elasipodida. A high percentage of the species of this group are now recognized as being cosmopolitan, and while 44 species are known from Antarctic and Subantarctic waters, the systematics are likely to be modified when revision is possible. Amongst the 38 species recorded from the coastal waters of Antarctica, the families Sclerodactylidae, Placothuridae, Vaneyellidae, Rhopalodinidae, Holothuriidae and Stichopidae are not represented. Representatives of the families Molpadidae and Apodidae, although well represented in Subantarctic waters have only one representative each in the Antarctic waters. Only one representative of the family Phyllophoridae (Huvelockia seczcnda Vaney) is present although there are eight species of the deep sea family Synallactidae. A majority of the species (28) belong to the dendrochirotacean families, Psolidae and Cucumariidae. Pawson (1969a, p. 37) supposes that the fact that members of these two latter families seem able to acquire the habit of viviparity or brood-protecting may well account for their relative success in Antarctica. Of the 20 genera amongst which these 38 species are distributed,

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only the monotypic genus Paracucumis appears to be endemic although Ekmocz~cumisis largely confined to the Antarctic with five of its six species endemic (including South Georgia) and the other species occurring in South Georgia and the Falklands. The other 18 genera are more or less widely distributed in the oceans of the world. The holothurian fauna is thus fairly generalized. Similarly there is little sign of species diversity in the group. Considered at the species level, about 58% are endemic (71% if South Georgia is included). Of the remaining species eight are known elsewhere from South America and Kerguelen, one from Kerguelen alone, and two from New Zealand and South America. Southern South America thus seems to be the main pathway for holothurian migration. There are no other obvious relationships. Study of the distribution maps presented by Pawson (1969) makes it clear that the distribution of Antarctic holothurians is only poorly known, and Pawson had stated that the most up to date information available on Antarctic holothurians was Ekman’s paper in 1925. Thus the collections made over the last 15 years have not been available, nor have the collections made by some earlier expeditions, notably the Discovery Collections. It is also obvious that the records for the Subantarctic are much better documented. Under the circumstances consideration of the distribution of the holothurians within the Antarctic area is probably not very profitable. From the fact that a number of species have been recorded from one or two areas in East Antarctica and from West Antarctica it would seem fairly obvious that a fair percentage of the typical Antarctic species will prove to be circumpolar in distribution. A peculiar member of the Psolidae from off the Antarctic Peninsula in 2 763 to 2 818 m proved to have a lateral sole instead of the usual ventral sole as developed in the rest of the family. Pawson (1971) described this form as a new genus and species, Ekkentropelmac brychia.

R. Ascidiacea The ascidian fauna of the Antarctic is large and varied. It has been made known in a long series of papers from those on South Georgia by Pfeffer (1889) and Michaelaen (1898, 1900) to the series of expedition reports by Herdman (1902,1910,1912,1923), Sluiter (1905, 1906,1912, 1914, 1932), Hartmeyer (1911), van Beneden and Selys-Longchamps (1913), Harant and Vernihes (1938), h b a c k (1938, 1950), Kott (1954, 1969a), Millar (1900) and Vinogradova (1962). It is one of the few groups for which we have a modern comprehensive monograph (Kott, 1969a) based on most of the recently collected material. Kott (1969b) has also

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recently given an account of the distribution of selected groups. Kott’s monograph describes, figures and discusses 122 species of both Antarctic and Subantarctic forms. Her bibliography is particularly full for ascidians in general, as well as Antarctic species. Kott analysed the geographic and bathymetric distribution of Antarctic ascidians in relation to her own biogeographic scheme for the Antarctic which although claimed as being a combination of Powell (1965) and Andriashev (1965), is in fact almost the same as that proposed by Knox. It is, however, difficult to know whether Kott includes the Antarctic PeninsuIa in the Continental Province or the South Georgian Province, or South Georgia in the South Georgian Province of the Antarctic Subregion or in the Magellanic Province of the Subantarctic Subregion. Much more is involved in this issue than a mere problem of semantics, since Kott’s study is one of the few modern monographs of a complete group based upon practically all the most important recent collections. I n another publication in the same year, Kott (1969b) presented a biogeographical scheme which resolved these difficulties. Here the Antarctic region (south of the Antarctic Convergence) is divided into a Continental Province (the circumpolar region near the continent) and a South Georgian Province ( ‘ I the Antarctic Peninsula and the Subantarctic (sic) islands along the Scotia Ridge to South Georgia ”). The Subantarctic Region is defined as being between the Subtropical and the Antarctic Convergences. Kott finds some evidence for an “ eastern ” district of the Continental Antarctic Province, in that a few species are to date recorded only from the Enderby and Victoria quadrants. Kott (1969a, 207) identifies the following groups of ascidians based upon their distribution. 1. Species distributed in the ‘‘ antarctic subregion ” (the “Antarctic ” of the present work) reaching at least to the South Shetlands and often extending north into the subantarctic. Most of the species in this group are circumpolar, and many are circumpolar in the Subantarctic. They occur over most of the shelf and into the deeper waters of the slope. With few exceptions they have a minimum depth range of 400 m. Kott suggests that their persistence in antarctic waters may well be due to their wide depth tolerance allowing them to escape the effects of glaciation on the shelf. Kott considers that some 30 species fall into this group. 2. Species with a limited distribution in the “ antarctic subregion ” (Antarctic). The occurrences of these eight species are based on comparatively few records. They all also have a limited bathymetric range, and may well represent recent derivatives. Only one species,

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the specialized CnemicEomrpa zenkevitchi Vinogradova has been recorded from less than 60 m. The greatest depth range for any of these species is 200 m (Aplidium vastaturn (Sluiter)). 3. Species with a limited distribution in the antarctic subregion, Georgian province. I n Kott's sense this province extends from the Bellingshausen Sea, along the Antarctic Peninsula, and through the South Shetlands, South Orkneys and South Sandwich Islands to South Georgia. This is an " overlap '' zone where six subantarctic species extend south to the South Shetlands or the Antarctic Peninsula, while nine antarctic species extend to varying degrees to the north. Kott (1969b) concluded that Antarctic ascidians are more diverse than would be expected considering the physical conditions. Some 92 species are recorded from shelf and slope, of which 16 extend north of the Subtropical Convergence. Between 2 000 and 6 000 m, 21 species have been obtained. Only six of these have been recorded from other abyssal basins. Kott suspected that certain of the obvious adaptations seen in the Antarctic ascidians have assisted in their success in the area. There are large populations of single species. Some species obviously live for a long period resulting in giant forms, e.g. Molgula gigantea Herdman and Paramolgula gregaria (Lesson), both from the Antarctic, are the largest simple ascidians known, Paramolgula attaining a length of 330mm. The grmter prevalence of viviparous species, and special adaptations in relation t o this are discussed in the general section on viviparity and brooding amongst Antarctic animals. Most successful species in the Antarctic are obviously able to tolerate a wide bathymetric range, a facility which is important in a region where shallow water is usually untenable for fixed forms, and where the shelf in places may be exceptionally deep, and in others be almost lacking. Kott suggested that one of the responses to the physical conditions for life in Antarctic seas may well be the general convergence in external characters which many ascidians from very diverse families exhibit. Amongst the Antarctic ascidians there is a high degree of speciiic and generic endemism. Thus the abyssal genera Protoholozoa, Pharyngodictyon, Abyssascidea and Fungulua, and the shallower water Bathypera, Pareugyrioides, Caenagneaia, Alloeocarpa and Oligocarpa are all endemic. The genus Sycoxoa may well have developed in Antarctic waters, but has since spread widely in the Southern Hemisphere. Many of the species are adapted for life on the open sea bed of the Antarctic continental shelf. Large numbers of sand or mud dwelling members of the family Molgulidae occur, and some species of the families Ppridae, Styelidae and Agnesiidae all show adaptations for

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this kind of environment. Other species of the Pyuridae and Styelidae and species from the families Corellidae and Ascidiidae have modified the shape of their attachment area for attachment to stones or shells, or have developed stalks. Kott’s distributional data can be presented with a different emphasis. Taking the boundaries of the Antarctic region in the sense they have generally been accepted in the present work (including South Georgia) and excluding abyssal forms, it would appear that some 73 species are now known. Of these 41 (56%) are known from nowhere else. Ten species seem to be known only from East Antarctica, eight of these being endemic and two having a wide distribution elsewhere in the Southern Hemisphere. A further 10 species which occur in East Antarctica extend as far as West Antarctica but do not extend beyond the Antarctic Peninsula (eight are Antarctic endemics, two have wider distribution outside the area). An additional three endemic species also occurring in East Antarctica extend as far north as the South Orkneys, while another seven endemic species reach South Georgia. Four more reach the Magellan area (two of them widely distributed Southern Hemisphere forms). A further eight species extend from East Antarctica to the Magellan region and the Subantarctic Islands (two are also more widely distributed in the Southern Hemisphere). Two more have a similar distribution in the Antarctic and Subantarctic but have not yet been recorded from the Magellan area. The rest of the Antarctic species are not known from East Antarctica. One species seems to be confined to the Weddell Sea, with another four endemic to the Antarctic Peninsula. Pive endemic species are shared between the Antarctic Peninsula and the South Shetlands. The South Shetlands has one endemic species, plus the sole representative known in the Antarctic for another widely distributed Southern Hemisphere species. One species extends from the Antarctic Peninsula to South Georgia, one species is confined to the South Orkneys and South Shetlands. South Georgia seems to have two endemic forms, shares two species with Subantarctic Islands, three species with the Magellan area and two species with the Subantarctic Islands and the Magellan area. Many Antarctic species appear to be circumpolar, e.g. Sycozoa georgiana (Michaelsen), Distaplia cylindrica (Lesson), D . colligans Sluiter, Tyiobranchion speciosum Herdman, Aplidium radiatum (Sluiter), A. circumvolutum (Sluiter), Ascidia challengeri Herdman, Caenagnesia bocki Anback, Cnemidiocarpa verrucosa (Lesson), Styela nordenskjoldi Michaelsen, S. insinuosa (Sluiter), S. pfefferi Michaelsen, Pyura

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georgiana (Michaelsen), P . discoveryi (Herdman), P . setosu (Sluiter), Bathypera splendens Michaelsen, Molgula pedunculata Herdman, M . malvinensis Arnback, M . gigantea Herdman and Pareugyrioides arnbackae (Millar). One ascidian which raises immensely interesting theoretical considerations is Cnemidiocarpa zenkevitchi (Vinogradova, 1958) from brackish water bays off the Knox Coast. This form is obviously derived from the widespread Antarctic C. verrucosa. It may represent an adaptation to the peculiar physical conditions in these bays which have the entrances blocked by ice in the winter and are subject to a considerable influx of fresh water run-off in the summer. Some fish remains and echinoderms were also found in the area but apparently little else. It would be of great interest to ascertain if any other animals show comparable adaptations . The ascidians are one of the few groups where the recent collections have been worked on and where therefore the abyssal forms are reasonably well known. It has often been speculated that some elements of the present shelf and slope Antarctic fauna might well have been derived from adjacent abyssal basins, especially since the water temperatures in these great depths will be no lower than Antarctio shelf waters (Broch, 1961; Dell, 1965, etc.). Kott (1969a) has shown that this does not appear to be true for the ascidians. Only Styela mrdenskjoldi, Pyura squamata Hartmeyer and some species of Bathypera were taken both from the Antarctic continental shelf and from the contiguous abyssal basins. The Antarctic abyssal fauna is peculiar in its endemic genera Protoholozoa, Pharyngodictyon, Abyssascidia and Fungulus. Abyssal ascidians in general show a tendency towards certain modifications, e.g. branchial sac wide and open, stigmata considerably enlarged or lost, test delicate, usually transparent, often stalked. These modifications show up in a reasonable proportion of the Antarctic abyssal fauna, thus indicating that it has been long established. Vinogradova (1962) recorded the collection of simple ascidians found during the Soviet expeditions in the Indian Ocean sector. Some 110 specimens were collected from 14 stations ranging in depth from 64 to 3 800 m. Vinogradova identified 17 species arranged in 9 genera from the families, Rhodostomatidae, Styelidae, Pyuridae and Molgulidae. Five of these species were described as new, including the rather strange Cnemidocurpa barbata Vinogradova which has developed long villi which help anchor the animal to soft substrates. One of the species discussed, Bathypera splendens is known to occur over a wide bathymetric range, from 170 t o 4 636 m. Millar (1971) in a general review of the biology of ascidians discussed

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the Antarctic fauna. In this group of animals the Antarctic does not seem to support an appreciably greater number of species than occurs in Arctic seas. Millar doubted if evidence for the prevalence of viviparity cited by Kott was any more than slight, and also doubted if the families Corellidae and Agnesiidae really presented a primitive Antarctic element.

S. Pishes The fishes of Antarctica have undoubtedly received more attention in the literature than any other benthic group. They have also undoubtedly been treated in greater depth particularly in relation to physiology. The Erebus and Terror collected fishes on Sir James Clark Ross' voyage round the world, and in fact this is one of the few groups of benthic animals to be written up as an official account of the expedition (Richardson, 1844-48).Unfortunately the two fishes illustrated from the Ross Sea have not proved recognizable subsequently. The specimens were not preserved, one having been eaten by the ship's cat. The literature of Antarctic fishes is plagued by small preliminary papers describing single species of fishes, and single observations. It is perhaps most useful to trace the main stream of expedition and large acale reports as a framework. Boulenger (1902) described the fishes collected by the Southern Cross and the National Antarctic Expedition (1907). Do110 (I 904) wrote the official report on the fishes of the BeZgica, preluded by a series of small papers (1900a, b, c, d) and followed by a series of small papers on the fishes of the Scottish National Antarctic Expedition (1906a, b, l908,1909a, b). Loennberg (1905)reported on the fishes of the Swedish South Polar Expedition. Vaillant (1906b) reported on the fishes of the first French Antarctic expedition. Roule, Angel and Despax wrote the official report on the fishes of the second French expedition, Roule having published preliminary papers (1911, 1913) himself and with Despax (1911). Pappenheim wrote the official section on the fishes of the German South Polar Expedition (1912) having produced a single preliminary paper (1911). Wrtite wrote the account of the fishes of the British Antarctic Expedition, 1907-09 (1911) and that of the Australasian AntarcticExpedition (1916).The two British giants in the field then took over work on the fish fauna of the Antarctic. Regan (1913)wrotethe officialaccount of the Scottish National Antarctic Expedition, and followed this (1914a, b) with the account of the material collected by the Terra Nova. Norman, in a series of large papers dealt with the fishes collected by the Discovery Investigations,

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the major one concerning the Antarctic in the restricted sense being on Antarctic coast fishes (1938). He also wrote up the collections of the B.A.N.Z.A.R. Expedition (1937b),with some preliminary diagnoses of nototheniiform fishes (1937a). Schultz (1945) commented on the small collection of the United States Antarctic Service Expedition (1939-41). Nybelin (1947) published an important contribution to Antarctic ichthyology in describing the collections of the Norwegian Antarctic Expedition, followed by an account of the fishes of the Brategg (1951), and of the Norwegian-British-Swedish Antarctic Expedition (1949-52) (1952). From here on it may be simpler to treat the historical account on a national basis. The entry of Soviet expeditions into Antarctica with the I.G.Y. brought another very distinguished ichthyologist into intimate contact with southern faunas in the person of Andriashev. He has been concerned with the total fish fauna and has made important contributions to our knowledge of pelagic fishes as well as the benthic fauna, apposite to the present review. In a series of papers (1958 t o 1964) he, together with co-authors, has summarized Soviet investigations, culminating in a masterly summary (1965) of the Antarctic fish fauna. Other Soviet ichthyological contributions have come from Barsukov and Permitin (1958) and Korotkevich (1964). Modern French biological work in the Antarctic has produced a series of useful contributions on the fishes. Blanc (1952, 1961a, b), Blanc and Hureau (1962), and Hureau (1962b, 1963a, 1964b, 1970) and Hureau and Arnaud (1964) have published papers concerned mostly with systematics and distribution. Other aspects have been treated also, e.g. otoliths (Hureau, 1962a),thyroid glands (Hureau, 1963b) and general biology (Hureau, 1964a). Two papers on the fishes of the South Orkneys resulting from Argentinean biological work have been contributed by Bellisio (1964, 1965). The recent work of United States scientists falls into two main categories, systematics (and distribution) and physiology. Reviews of previous work were given by Rofen and DeWitt (1961) and for the Ross Sea by Miller (1961a). The main contributions to systematics have come from DeWitt (1962a, b, 1964a, b, 1965), DeWitt and Tyler (1960), Miller (196lb), Miller and Reseck (1961) and Reseck (1961). American physiological work has centred around Wohlschlag who in a long series of papers from 1969 to 1965 has reported the results of investigations particularly those carried out at the laboratory at McMiirdo Sound. Dearborn (1965) reported on investigations on reproduction in the common Antarctic fish (Trematmnus). Other physiological work is summarized under the general account later. Papers dealing

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with I‘ white blood ” and the “ giant fish of the Antarctic ” are noted in subsequent sections. The fishes of South Georgia are treated incidentally in many of the papers listed above. Contributions referring solely to South Georgia have been Hubbs (1934), 01sen (1954, 1955) and Carrara (1955). A valuable, well balanced account of the development of our knowledge of Antarctic fishes was given by Andriashev (1965), followed by a general account of the composition and distribution of the fauna. The whole style of this contribution together with its carefully chosen illustrations and bibliography make it a most useful source of information for the biologist who is not an expert on fishes. 1. Composition of the benthic fish fauna of Antarctica

(after Andriashev, 1965)

A relatively few families are represented in the Antarctic fauna proper. Family Myxinidae. One species of the hag fish Myxine has been taken on one occasion near the South Shetlands.

FIG.14. Representatives of two typical Antarctic families of jishes. A. Muraenolepk microp8 Loennberg, Family Muraenolepidae (redrawn after Regan) ;B.Paraliparb antaTCtiCU8 Regan, Family Liparidae (redrawn after Regan).

Family Rajidae. One species has been recorded from the Bellingshausen Sea on the basis of egg capsules alone, and one young specimen has been described from South Georgia. Family Muraenolepidae (Fig. 14). This is a typical Antarctic family, three species occurring in Antarctic waters, and the only other known

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member on the Patagonian shelf. The family is considered to be the most primitive representative of the cods. Family Nototheniidae. Four of the known five genera with no less than 21 species occur in the Antarctic. Family Harpagiferidae. Four genera of Plunder fishes, Artedidraco, Dolloidraco, Histiodram, and Pogonophryne, with eight species inhabit the shelf of the Antarctic Continent. The fifth genus, Harpagifer is almost entirely Subantaretic, with one species occurring off the Antarctic Peninsula. Family Bathydraconidae. The Antarctic dragon fishes are another typical Antarctic family, six of the genera and 13 species occurring along the coasts of the Antarctic continent. Family Chaenichthyidae. The white-blooded, or ice fishes, have become the most renowned group of Antarctic fishes since recent investigations showed that all members of the family have colourless blood with neither haemoglobin nor erythrocytes. Eleven species belonging to seven genera have been recorded from Antarctic coasts, with additional species and genera in South Georgia and the Subantarctic. Family Zoarcidae. The eel pouts are essentially a Northern Hemisphere family, very well represented in the Arctic and northern Pacific and Antarctic Oceans. However, four genera with five species occur in the Antarctic with many additional representatives on the Patagonian shelf. Family Liparidae (Fig. 14). The distribution of the family of sea snails is similar to that of the Zoarcidae. Two species of the genus Paraliparis occur in Antarctic waters, with another three species belonging to two genera in South Georgia. Family Bothidae. The left-eye flounders are characteristic of tropical and subtropical waters. A member of the genus Achiropsetta occurs in the Antarctic, with a species of Manmpsetta in South Georgia and the Subantarctic. The abyssal fishes of the Antarctic are poorly known as yet. The deepest bottom living fish so far known is Bassogigas brucei (family Brotulidae) from 4 571 m in the Weddell Sea. The majority of the rest of the known abyssal fauna belonging to the family Macrouridae (rat tails). The outstanding feature of the systematic composition of the Antarctic bottom fish fauna is the overwhelming part played by the one superfamily, the Notothenioidea (Nototheniiformes) (Fig. 15). This superfamily comprises the four Antarctic families, the Nototheniidae, the Harpagiferidae, the Bathydraconidae and the Chaenichthyidae, together with the essentially Subantarctic family, the Bovichthyidae.

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Ro.16. Representatives of the four Antarctic families of the Nototheniiformes. A. Bathydraco macropeli8 Boulenger, Family Bathydraconidae (redrawn after Boulenger) ; B. Histiodraoo uelijer (Regan), Family Harpagiferidae (redrawn after Regan) ; C. Trematornwr bernacchii Boulenger, Family Nototheniidm (redrawn after Boulenger) ; D. Pagetop& rnacropterua (Boulenger), Family Chmnichthyidae (redrawn after Boulenger).

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Of the 67 species of fishes recorded from Antarctic waters proper, no less than 54 (81%) belong to this single superfamily. Nor is this only an apparent statistical paper predominance. Members of the superfamily are extremely common and important ecologically in the field. A closer analysis of the group will bring out a number of points of interest. The genus Notothenia itself with some 30 species has a few species distributed around the Antarctic Continent and the Scotia Arc, with a majority of species in the Subantarctic extending to southern South America and southern New Zealand. Most of the species are bottom fishes of the shelf extending down to 500 m or so. Only two species occur in deeper water down to 700 m. The genus Trematomw on the other hand is largely confined to the continental shelf of Antarctica. The 13 known species occur from about 20"W around to 180"E (the whole coast of East Antarctica) but only seven species have been recorded from West Antarctica, with two species in South Georgia. Three species, T . borchgrevincki Boulenger, T . brachysoma Pappenheim and T . newnesi Boulenger, commonly occur in the midwater and surface layers. The rest are largely bottom dwellers when adult. One large group including T . scotti (Boulenger), T . lepidorhinus (Pappenheim), T . eulepidotus Regan and T . loennbergi Regan seem to be confked to deeper water (Andriashev, 1965, p. 501). Three species are common in shallow water near shores, T . nicolai (Boulenger), T . hunsoni Boulenger and T . bernacchii Boulenger. I n McMurdo Sound, Wohlschlag (1964, p. 35) trapped T . bernacchii, T . hunsoni and T . centronotus Regan regularly in depths up to 50 m. At about 250 m T . bernacchii and T . hunsoni were taken by the fish traps, while in 500 to 600m T . Zoennbergi was the main notothenioid fish taken, Wohlschlag stressed that traps seemed to be effective only with some benthic species. Tremtomus bernacchii must be one of the most intensively studied of the Antarctic fishes. Some features of its biology will be outlined later. Thus within the genus Trematomus itself there has already been a quite remarkable series of adaptations to very different life habits. The only true pelagic, plankton feeding form in the family is, however, Pleuragramma antarctica Boulenger which has taken on the herring-like appearance of many fishes of similar habit. The genus Dissostichus, especially the giant Antarctic species, D . mawsoni Norman, became one of the Antarctic legends long before its true nature had been appreciated by scientists. Besides showing adaptations to various widely different ecological niches, the Nototheniidae provide some of the commonest and most important ecologically of the Antarctic coastal fish fauna, and the largest by far of the Antarctic fishes. Other members of the superfamily, the

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Harpagiferidae, Bathydraconidae and Chaenichthyidae, are again three very distinctive and most characteristic groups of Antarctic fishes, while the third family has proved to have a character unique in the vertebrates, colourless blood, with no haemoglobin and no erythrocytes. 2. The giant Antarctic fish, Dissostichus mawsoni

The development of our knowledge of Dissostichus mawsoni is worth outlining as an example of some of the problems which have faced Antarctic biology. Only the major steps in a complicated story can be mentioned here. The species was described by Norman (1937, p. 71) from a unique specimen, 370 mm in length trawled from 66’45‘5, 62’03’E in 219 m. Norman had no reason to believe that this was in fact a small example of what had been long before recognized as the giant of Antarctic fishes in popular knowledge though it had not been scientifically described. A large headless fish had been harpooned together with a seal on Scott’s National Antarctic Expedition (1901-04). It was recorded in objective fashion as Notothenia sp. by Boulenger (1907) in the scientific account of the fishes of this expedition, but the body had been long before eaten by the expedition members. Scott (1929, p. 570) gave a much more spirited account, perhaps with gastronomic bias, of this specimen, 3 f t 10 in in length and weighing 39 lb. It was a long time before the ‘‘ giant Antarctic fish ’’ of the expeditions was to be properly linked with Norman’s scientific description. The I.G.Y. and post-I.G.Y. flurry of activity in Antarctica brought many more men to the ice. Observations of giant fish began to accumulate. Swithinbank, Darby and Wohlschlag (1961) recorded finding several large fish, the largest 142 cm in length, on the surface of the ice in McMurdo Sound. Stimulated by this account, Debenham (1961) discussed the six headless specimens encountered by Scott’s two expeditions and postulated methods by which all of these could have reached the ice surface. This account is of interest since it demonstrates the long period over which “ the headless giant fish of McMurdo Sound ” had remained unidentified, and also the lack of appreciation of the role of what is now known as “ anchor ice ” in these extremely cold waters. Andriashev (1962) showed that the large fish mentioned by Boulenger from McMurdo Sound was in fact what Norman had described as Dissostichus mawsoni, and also recorded the occurrence of pelagic young in Antarctic waters. By this time records of large (often headless) fish from around the holes used by Weddell Seals in McMurdo Sound were becoming moderately common, although popular accounts often still referred to the fish as “ unknown to science ”.

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Dearborn (1965s)in a study of the food of Weddell Seals at McMurdo Sound recorded three large specimens identified as Dissostichus mawsoni (the largest weighing 26.3 kg) as having been taken from seals, Wohlschlag (1968) in a semi-popular account, commented that many specimens had been captured in seal holes a t McMurdo Sound (including one 53 in long), and gave a figure of 429 mg/h at resting conditions for oxygen consumption of a live specimen! It was left, however, for two New Zealand geophysicists, Calhaem and Christoffel (1969) to give an account of the technique used by Weddell Seals to capture specimens of this fish, and to publish photographs of the seals carrying fish, and even good photographs of the fish itself, in a scientific journal. The largest specimen measured by them (and now preserved in the Dominion Museum, Wellington), was 147 cm in length and weighed 30 kg. The two authors recorded the behaviour of a particular Weddell Seal in bringing specimens of Dissostichus (ranging in size from about 15 to 651b) to the surface, and first holding the fish’s head out of water before eating it below the surface. 3. White-bloodedfishes The peculiar lack of haemoglobin in the blood of members of the family Chaenichthyidae has occasioned a great deal of scientific interest since the phenomenon was reported by Nybelin (1947) and brought more forcibly to attention by Ruud (1954). Confirmation of the possibility that all fishes belonging to this family might show the same characteristics was quickly obtained through the research of the Russian biologists, Andriashev and Tokarev (1958) and Barsukov and Permitin (1958). Andriashev and Tokarev (1958) and Ruud (1958) demonstrated that the condition could be checked in preserved specimens. It now appears that the lack of haemoglobin and the virtual absence of erythrocytes is a family characteristic. Martsinkevitch (1958, 1961) demonstrated that cells similar to erythrocytes occurred in the blood vessels of internal organs, but these were so rare they could hardly be functional in oxygen exchange. Walvig (1958) examined blood and parenchymal cells in the spleen of Chaemocephalus, and (1960) looked at the integument as a possible area of oxygen exchange. The respiratory rate for one of the Chaenichthidae, Chaenocephalus aceratus (Lonnberg) from off the South Orkneys proved to be strictly comparable to that for three members of the genus ~ o t o t h e (Ralph ~i~ and Everson, 1968). Oxygen appears to be transported in the blood stream in physical solution. It had been believed that oxygen exchange might take place largely through the skin, or through the extensive gill

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surface. However, the major method of oxygen transportation seems to be through the normal circulatory system (Hemmingsenand Douglas, 1969). The rate of oxygen consumption in Pagetopsis macropterus Boulenger proved to be one half to one quarter that of other Antarctic fishes (Hemmingsen, Douglas and Grigg, 1969). Some work has indicated that the white blood of the Chaenichthyidae is not as sharply differentiated a phenomenon as had been at first supposed. Two red blooded Antarctic species, Notothenia larseni Lijnnberg and Trematomus borchrevinki proved to have a reduced number of erythrocytes and a low haemoglobin count compared with other fishes (Tyler, 1960). Other Antarctic species may well show reduced amounts of haemoglobin. The possibility of gaining enough oxygen from physical solution in the blood plasma may well be correlated with the generally rather sluggish habit and the cold temperatures. Kooyman (1963) examined four species of Tremtomus from McMurdo Sound and concluded that although the figures for haemoglobin and erythrocytes were low as compared with temperate fishes, they were far from lacking them. As Andriashev (1965, p. 529) pointed out, this family must be considered to be successful biologically. Most species of the family range along the coasts of the Antarctic Continent, but they also extend to South Georgia, southern South America and Kerguelen. These habitats encompass a range of water temperature from -1.95OC up to 5" or 8°C. The species are all of reasonable size, they occur in depths from the shore to 700 m, they have representatives adapted to benthic and nektonic habitats. I n the absence of any contrary fossil evidence one can only consider the family one that has evolved in southern areas, and that the whiteblooded condition is of very considerable age. 4. Trematomus bernucchi

Because of its abundance in many areas around the Antarctic Continent, and particularly near the United States laboratory at McMurdo Sound, Trematomus bernacchi has been used extensively in studies on Antarctic fishes. A large amount of information is now available based upon studies of this species, or using this species as a base line. Thus the following aspects have now been covered : general biology (Hureau, 1964a),reproduction (Dearborn, 1965a),diet (Amaud and Hureau, 1968), metabolic level (Wohlschlag, 1960), growth and age-determination at freezing temperatures (Wohlschlag, 1961a), metabolic differences between the sexes (Wohlschlag, 1962), respiratory metabolism and general problems relating to cold adaptation (Wohl-

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schlag, 1964), anatomical modifications of significance in relation to the cold environment (Morris, 1966), and temperature tolerance (Somero and DeVries, 1967). Trernatomus bernacchi ranges around the Antarctic Continent, and as far north as the South Shetlands and South Orkneys. The species can live under sea ice for most of the year if not permanently. Much of the American work was carried out under the leadership of Dr Donald E. Wohlschlag acting as leader for the Stanford University project on fishes from 1958 to 1965. Using portable field huts mounted over holes cut through the ice, sampling programmes were maintained throughout the year. Five or six species of fishes could be caught commonly by lines or traps, and about the same number infrequently. Trernatomus bernacchi appears to be active throughout most of the year. Specimens collected during the winter normally had benthic organisms present in their stomachs, indicating that feeding continued throughout the year. Stomach contents indicated that the fish is carnivorous and on occasion necrophagous (Wohlschlag, 1961). I n McMurdo Sound the habitat of T . bernacchi remains at about -1.9"C throughout the year, but Wohlschlag demonstrated that scale rings could be used for ageing populations. Using this evidence he showed that Antarctic fishes living in subzero temperatures were able to sustain a growth rate comparable with Arctic species living where temperatures may reach 10°C for two or three months, and where most growth is achieved during the summer period (Wohlschlag, 1961). Reproduction in Trematornus bernacchi has been studied by Hureau (1964a) off Adelie Land (66"s) and by Dearborn (1965) in McMurdo Sound (nearly 78'5). Dearborn examined 503 freshly caught specimens, taken from depths ranging from two to 270 m. The number of welldeveloped eggs in any one individual ranged from 1 154 to 3 123. The eggs are large and yolky, ranging from 1.9 to 3.9 mm in diameter, but with the majority between 2.6 and 3.7 mm when fully mature. Dearborn believed that the available data indicated that T . bernacchi breeds annually in McMurdo Sound, the eggs developing throughout the winter, with the ova released in December and January. Hureau (1964) studying the same species off the Adelie Coast found a similar cycle, except that spawning took place from mid-October to midNovember. Females appear to spawn first at about five years of age in both localities. The eggs are apparently demersal, and off Adelie Land are attached to algae. Direct evidence for demersal spawning is lacking at McMurdo Sound, but no eggs have been obtained in very numerous plankton tows.

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Females with ripening eggs, especially in late August have much lower respiratory levels than males or immature females (Wohlschlag, 1964). This may well result in different behaviour patterns between males and mature females at this time and may well account for only males being caught by line and trap at this period of the year. Too little is known as yet of the possible causes of different breeding periods in such areas as McMurdo Sound and the Adelie Coast, separated by about 670 latitudinal nautical miles. Similar differences have been noted for the starfish, Odontaster validus (Pearse, 1965). Sea temperature differences are slight, but even these slight differences have been shown to be sufficient to cause appreciable changes in the abundance of phytoplankton. Pearse (1965)has suggested that the time the shelf ice breaks out may have more significance than temperature as such. Wohlschlag (1964) has given a summary of his work on the physiology of Trematomus bernacchi, and has given details of his methods in a series of papers (Wohlschlag, 1959-64). Oxygen consumption rates increased with rising temperatures up to about 0°C and above that decreased (Wohlschlag, 1960). On the whole throughout the year there were only slight differencesbetween the sexes in respiratory rates except for a very great difference for late winter collections from very deep water, a phenomenon which Wohlschlag considered of purely local significance. Females in this species appear to have much faster growth rates,and much higher survival rates than do males (Wohlschlag,1961a), possibly a direct correlation of their lower metabolic maintenance requirements (Wohlschlag, 1962b). Field observations indicate that many of the Nototheniiformes are relatively inactive in life, and laboratory experiments bear this out. Slight artificial rises in temperature cause a tendency to swim even more slowly. Their optimum swimming speed is obtained at the lowest possible temperatures (i.e. those found in their normal habitat), in contrast to the results obtained with temperate species. Some specimens of T . bernacchi can live for long periods under sea ice (perhaps even permanently). Specimens collected from beneath the Koettlitz Glacier at Heald Island are paler coloured than fish from open waters, or from under the annual ice sheet. These fishes from deep water appear to have a significantly lower metabolism than those from areas with good light penetration. 5. General Antarctic fish physiology

Work has begun to try to determine something of the modifications in these fishes which are of adaptive significance for cold conditions.

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Morris (1966) reported that investigation of the possible effect of the thyroid in maintaining the high metabolic rate showed no significant results. Somero and DeVries (1967) showed that three species of Trematomus including T . bernacchi survived supercooling to -2.5OC but that the upper lethal temperature of 6°C is unusually low. The main site of thermal injury appears t o be the central nervous system. DeVries (1969) reported low blood serum freezing points from -1.2OC to -2.O"C. No differences could be discerned between freezing resistances of fishes from McMurdo Sound and the Antarctic Peninsula. Glucoprotein appeared to be the main depressant factor. DeVries (1970) summarized the work on freezing resistance in Antarctic fishes. Fishes from deeper water in McMurdo Sound such as the zoarcid Rhigophila dearborni DeWitt and a liparid are supercooled. They survive in this state because there is no ice present. When they are drawn to the surface in traps during the winter, they pass through water containing ice crystals and promptly freeze. Other fishes occurring in the area showed a range of resistance to freezing. Some deep-water populations differed from shallow-water populations of the same species. Investigation of the serum structure shows that an efficient and complicated antifreeze substance is present. Sodium chloride is responsible for about 80% of serum freezing-point depression in temperate fishes. I n the Antarctic species of Trematomus studied, sodium chloride accounts for less than half of the depression. The other antifreeze substance appeared basically to be a protein containing carbohydrate. DeVries (1970, p. 328) gave a preliminary description of its structure in a postscript. The mechanism by which it achieves its quite spectacular results is still unknown. Fishes of the genus Notothenia, and one species of Trematomus studied at the South Orkneys (Smith, 1970) proved also to be supercooled. When these fishes did freeze the indications were that " seeding " took place with the presence of ice at the gills. I n contrast to the results on fishes studied at McMurdo Sound, depression of the freezing point of the blood serum appeared to be largely due to sodium chloride. Wohlschlag's work, especially on members of the Nototheniiformes, has shown that these Antarctic fishes have a higher metabolic level than fishes elsewhere, when compared with the same standards. The experimental work showed that these fishes have attained a very high level of metabolic cold adaptation. Wohlschlag believes that such fishes have a more efficient mechanism for converting energy into growth. Robilliard and Dayton (1969) reported on the general behaviour of

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one of the Chaenichthyid fishes, Pagetopsis macropterus, at McMurdo Sound. A specimen was captured by hand as it rested on a sponge. Whenever disturbed it swam slowly close to the bottom, and when left it came to rest on a sponge again. It was suggested that this may be its usual feeding position, raised somewhat in the water column, waiting for prey to swim past. Stomach contents of small fish and Crustacea in Pagetopsis seems additional evidence for this. These authors described a defence posture with dorsal fin erected, pectoral fins opened widely at right angles to the body, and the body bent. A wide range of oxygen consumption was recorded in this fish, and Robilliard and Dayton noted that the respiratory rates reported by various authors were somewhat discrepant. 6. Reproduction Marshall (196413) discussed what was known of reproduction in Antarctic fishes, especially in the Scotia Arc and the Antarctic Peninsula. Some evidence pointed to some Antarctic fishes spawning during the late spring and early summer. Eggs of Harpagifer bispinis (Schneider) have been collected in November, and recently hatched specimens of Artedraco and Gymnodraco acuticeps Boulenger in December and January. However, newly hatched larvae of Pagetopsis macropterm have been taken in May and June, and young larvae of Chionodraco kathleenae Regan in October. I n South Georgia the main spawning period appears to be in autumn, based upon the following observations : Paraliparis gracilis Norman (eggs in April), Champsocephalus gunnari Lonnberg (spawn in April, May), Chaenocephalus aceratus Lonnberg (spawn from late March to April) and Notothenia rossii Richardson (spawn in April and May). Marshall (196413, p. 215) believed that on all the evidence available to him most Antarctic species lay their eggs on the sea floor. He had previously (1953) shown that in comparison with temperate and tropical fishes with a similar habit of producing demersal eggs, the eggs of Antarctic fishes were larger and more yolky. Correlated with this was the observation that the larval fishes hatching from these eggs were larger and more advanced. The data available to Andriashev (1965) was in general agreement with Marshall’s conclusions. Larvae of Antarctic fishes are comparatively large, and many have a long pelagic stage. I n many species, the larvae, though pelagic, occur in midwater rather than close to the surface. As a result of an analysis of midwater fishes in the Ross Sea, DeWitt (1970)was able to show that even the juveniles of the dominant A.x.B.-~O

6

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benthic group of Trematomus species did not occur far from the bottom. Hureau (1970) has produced a comprehensive work on the biology of two species of Trematomus and four of Notothenia from Adelie Land and Kerguelen. Unfortunately this work came to hand too late to be properly considered in the present review. 7. Distribution of fishes

Andriashev (1965) has adapted from Nybelin (1947) a series of divisions of the Antarctic fish fauna based upon distribution patterns. Excluding a Kerguelen-type which is essentially Subantarctic, he distinguishes six distribution types. 1. Circumpolar-Antarctic type made up of species which are distributed around the Continent. This includes nearly 20 species, including some which reach the South Shetlands and South Orkneys, and two which reach South Georgia. 2. East Antarctic type composed of fishes found only in East Antarctica. Nybelin included 27 species in this group. Andriashev showed that Gymnodraco acuticeps must be excluded, but added at least four others. Five genera are confined to East Antarctica, Histiodraco, Neopagetopsis, Dacodraco, Chaenodraco and Lycodichthys. 3. West Antarctic type composed of fishes which are known only from the shores of West Antarctica and its associated islands. Of the eight species listed by Nybelin, only six can now be included, and some of these are rather uncertain (Andriashev, 1965). 4. West Antarctic-South Georgia type. Four species which occur in West Antarctica and also South Georgia (some also on the South Sandwich Islands) make up this small group which may represent only an extension of the West Antarctica type (Notothenia gibberifrons Lunnberg, N . nudifrons Lunnberg, N . larseni Lonnberg and Chaenocephalus aceratus. 5. South Georgian type. Nine or ten species of fishes are endemic to South Georgia, as are the two genera, Psilodraco and Pseudochenichthys. 6. Antarctic-Notal type (or mainly notal type) includes a few species off Patagonia or southern New Zealand which penetrate the peripheral parts of the Antarctic (or Subantarctic) including South Georgia. Based upon his analysis of fish distributions Andriashev (1965) divides the Antarctic Region into Subregions, Provinces and Districts (as discussed in the introductory section of the present work). Basically the subdivisions are arranged as follows.

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Antarctic Subregion

I.

QLACIAL SUBREGION

1. Continental Province ( a ) East Antarctic District ( b ) West Antarctic District 2. South Georgian Province

11.

KERQUELEN SUBREGION

The Antarctic Region includes the shelf and slope of the Antarctic Continent " and the islands lying to the south of and near the Antarctic Convergence ". Some 39 genera with 94 species have been recorded from the Region. Characteristics of the fauna include the overwhelming preponderance of notothenioid families to which 75% of the species belong, the complete absence of one notothenioid family, the Bovichthyidae, and the development of a primarily Antarctic suborder of fishes, the Muraenolepids. Endemism is high, 70% of the genera and 95% of the species being confined to the Region. The Antarctic Region is divided into a Glacial and a Kerguelen Subregion, only the first of which concerns us further. The Glacial Subregion includes the coasts of the Antarctic continent and the islands of the Scotia Arc including South Georgia, and Bouvet Island. The family Bathydraconidae with 15 species is endemic to the Subregion, as is the genus Trematomus with 13 species, and Artedidraco with five species. Ten of the species of Harpagiferidae are characteristic. Only seven of the 81 species recorded from the Subregion occurred outside its limits. The Glacial Subregion is divided into two provinces, the Continental Province and the South Georgian Province. The Continental Province embraces the coastal waters of the Continent together with the South Shetlands and the South Orkneys. Eleven genera are endemic for the Province (Pleuragramma, Dolloidraco, Pogonophryne, Clerlachea, Racovitza, Prionodraco, Qymnodraco,Pagetopsis, Cryodraco, Chionodraco and Austrolycicthys). Some 67 species are known, of which 19 are endemic. Andriashev believed that East and West Antarctica should be separated as two districts of the Continental Province. The East-Antarctic District musters 56 species arranged in 25 genera, with more than half the species, and five or six genera, endemic. The genus Trematomus shows a much greater diversity of species than does Notothenia. At the same time 40% of the species are also found in West Antarctica. The West-Antarctic District has not as yet clear cut boundaries.

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Of the 34 species known, over 66% also occur in East Antarctica. There are few endemic species and no endemic genera. The South Georgian Province supports 23 fish species (not counting the poorly-known macrurids, skates and liparids). Nearly 40% of the species are endemic, as are two genera. Species of Notothenia are much better represented than species of Trematomus. Strong relationships are shown with the West-Antarctic District (40% of the species in common), Kerguelen Subregion (25%) and East-Antarctic District (20%). Andriashev agrees that other methods of interpreting the same data are possible. He brings forward the interesting point that there is a progression from East Antarctica with a large land maw and the most extreme climatic conditions, to the smaller less severe Antarctic Peninsula, to the smaller still, much more benign South Georgia with a corresponding reverse progression in the number of species present from 56 in East Antarctica, 34 in West Antarctica and 23 in South Georgia. Because of the " sunken '' nature of the Antarctic Continental shelf, Andriashev (1965) cannot distinguish a group of littoral fishes except in South Georgia. Even the sublittoral group of fishes appears to be weakly developed in places. The greatest number of species is found between about 200 or 300 m and 500 or 600 m. Within this zone 80% of the known Antarctic fishes have been collected. This is in marked contrast to areas farther north where the number of benthic species usually decreases beyond 100 or 200 m. Some genera and species of typical Antarctic shelf families have adapted themselves to very deep water. Andriashev cites the following examples. Chaenichthidae - Pagetopsis, Dacodraco Harpagiferidae - Pogonophryne Nototheniidae - Trematomus loennbergi Bathydraconidae - Bathydraco scotiae Zoarcidae - Austrolycicthys - Lycenchelys

- to 655 m to to to - to - to -

850m 920 m 2579m 1 040 m 3 248 m

V. MBRINE ALGAE(Fig. 16) Since intertidal algae are hardly developed at all in the Antarctic, it was not possible to observe algal growth directly except in exceptional circumstances in a few areas, until SCUBA diving could be used in Antarctic waters. Until these new techniques showed the extent of sublittoral algal growth biologists, and especially zoologists, tended to ignore, or a t least to greatly underestimate, the proper role of Antarctic

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algae. There are admittedly few species, although some belong to peculiar, and as yet poorly understood genera. The contrast between the extremely rich development of very large brown algae such as Durviltea, Macrocystis and Lessonia forming a thick fringe around Subantarctic coasts and the bare ice-scoured rocks and white ice shelves of the Antarctic, is of course obvious to all investigators. Considering the collecting techniques available, and the fact that so few algologists worked in the Antarctic, it is not surprising that knowledge was slowly gained.

FIG.16.

Some typical Antarctic algae. A. Phycodrya antarctica (Skottsberg) ; B. Deamarealia menzieai J. Agardh; C . Phyllogigaa grandijoliua (A. and E. S. Gepp) ; D. ~ ~ y l antarctica ~ ~ ~ A. and o E. ~ 5. a Gepp. (A. B. redrawn after Zaneveld, C. D. redrawn after A. and E. S. Gepp.)

De Wildeman (1900) published a preliminary paper on the algae collected by the Belgica, but the full report did not appear until 1935. Barton (1902) supplied a basic list of the algae collected from Cape Adare by the Southern Cross. The collections made by the National Antarctic Expedition in the Ross Sea were written up by A. and E. S. Gepp (1907)and Foslie (1907b).Gain (1912)presented an account of the algae from the second French Antarctic expedition, while Lemoine (1912a, b, 1913) dealt with the calcareous red algae from the same source. The algae collected from the South Orkneys by the Scottish National Antarctic Expedition were described by Holmes (1905, 1912).

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Lucas (1919) gave an account of the collections of the Australasian Antarctic Expedition while Hedley (1916a) published some interesting field notes emanating from the same source. It is perhaps ironic that when an algologist and especially one of the stature of the Swede, Skottsberg, did have the chance to form a large collection during the course of the Swedish South Polar Expedition, the major part of it should be lost when the expedition vessel was destroyed in the pack ice. What survived to be written up by Kylin and Skottsberg (1919), Hylmo (1919) and Foslie (1907a), and the general account of algal communities by Skottsberg (194l), indicates the extent of this loss. Leaing (1945) described algae from some Antarctic and Subantarctic islands. During the wartime British excursions into Graham Land, known as " Operation Tabarin " from 1943 to 1945 MacKenzie Lamb collected extensively along the Antarctic Peninsula. Skottsberg (1953) wrote up a systematic account from these collections, together with the collections formed by the B.A.N.Z.A.R. Expedition. DBlBpine et al., (1966)gave a general account of the algae of the Antarctic Peninsula. Skottsberg and Neushul (1960) investigated the relationships of PhyZlogigas and Himantothatlua. Arnaud (1964) described a new red alga from off Adelie Land. Neushul (1965) reported on a further investigation of the algae of the Antarctic Peninsula using diving techniques. The culmination of this phase of investigation of Antarctic algae, which was primarily (though not entirely) systematic was the appearance of a catalogue and bibliography of Antarctic and Subantarctic algae (Papenfuss, 1964b). A large number of workers, especially the more recent ones, have been concerned with algal associations and zonation. Skottsberg (1941) attempted it pioneer general treatment especially for the area of the Scotia Arc. Neushul (1965) reported on diving observations off the Antarctic Peninsula. DBl6pine and Hureau (1963) described algal associations off Adelie Land. Zinova (1958) described algal associations in the Antarctic observed by the Soviet expeditions. Zaneveld (1966, 1968) contributed two detailed studies on the distribution of algae in the Ross Sea. Etcheverry (1968) described the sublittoral in some areas of the Antarctic Peninsula. Price and Redfearn (1968) described the sublittoral zone at Signy Island, South Orkneys. They included observations on animals as well and & short account of their observations is given under general ecology. Skottsberg (1964) contributed some general observations on the

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flora and Papenfuss (1964a) produced some stimulating ideas relating to problems in taxonomy and distribution of Antarctic algae. The algae of South Georgia have usually been treated in papers on broader topics. The two early papers by Reinsch (1888, 1890) were pioneer papers for the whole Antarctic. The other major contribution to South Georgia is contained in Skottsberg's (1941) more general account. A general synopsis of the history of algal collecting in the Antarctic was given by Gain (1912). Skottsberg (1964) gave a brief account of subsequent efforts up to that date. He also attempted an analysis of the Antarctic flora. Papenfusa' list (1964b)gives the basis for an additional analysis but considerable data has accumulated since then, especially as a result of diving to 30 M or so. Skottsberg at the end of a life devoted to the study of southern plants (1964, p. 151) restated his belief that the Antarctic Convergence more or less separated an Antarctic from a Subantarctic algal flora. The large brown algae Nacrocystis, Lessonia and Durvillea, so characteristic of Subantarctic Island shorelines, disappear as one moves south together with Ulva, Bryopsis, Codium, Ectocarpus, Pylaiella, Chorderiaceae, Encoeliaceae, Sphacelariaceae, Bostrychia, Chaetangium, Qelidium and Corallina. In their place the truly Antarctic species develop, but never in the same luxuriance. The most recent general account of the distribution of marine benthic algae has been given by Neushul (1968). Using the data assembled by Papenfuss (1964b)he calculates that of the algae confined to the Antarctic region, some 35% are endemic. Neushul distinguishes the following distribution patterns. 1. Species found only on the Antarctic Peninsula and the South Shetland Islands, e.g. Cystospbera ~ a c ~ u ~ n(Montagne) oti~ Skottsberg (Ascoseira is also a characteristio species for the area but has also been recorded from South Georgia). 2. Species found on the Antarctic Peninsula, the South Shetland8 Islands and north to the southern part of South America but not extending to the rest of the Antarctic Continent, e.g. Adenocystis utricularis (Bory) Skottsberg. 3. Species found in Antarctica except for the Antarctic Peninsula, but also in Subantarctic Islands between 50"sand SO'S, e.g. Phyllophora spp. and Plocamium spp. 4. Species which extend around the Continent but are not generally found north of 60°S, e.g. Leptosomia simplex (A. and E. S. Gepp) Kylin and Phyllogigas grandifolius (A. and E. S. Gepp) Skottsberg. 6 . Species which similarly extend around the Continent and which

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also extend to areas between 50"s and 60"S, e.g. Ballia callitricha (Agardh) Kutzing, Desmarestia menziesii J. Agardh, and Iridaea. The fact that there are no algal records for the Antarctic coast from 72"W to 173"E and from 50"W and 40"E and that Plocamium and Iridaea collected from Peter I Island constitute the only algae so far collected from the whole quadrant 90"-180"W (Neushul, 1968) show the incomplete data available. It has been suggested that some deep-water algae are heterotrophic. Neushul (1968) does not find there is any evidence for such a belief and Zaneveld (1968) does not think the occurrence of deep-water Antarctic macroscopic algae needs such an explanation. Four monotypic genera are found only on South Georgia, Melastictus Reinsch, Stegastrum Reinsch, Microrhinus Skottsberg and Pseudolaingia Levring. Other monotypic genera confined to the Antarctic are Phaeoglossum (found only on the Antarctic Peninsula), Phyllogigas (Antarctic Continent, South Shetlands, South Orkneys and South Georgia), Ascoseira (Antarctic Peninsula, South Georgia and South Shetlands), Cystosphuera (Antarctic Peninsula and South Shetlands), Nereoginkgo (Antarctic Peninsula and South Georgia), Plumariopsis (Antarctic Peninsula, South Georgia and Kerguelen), and Antarctocolax (Antarctic Peninsula). Marine algae do not as a rule have particularly restricted distribution patterns. The presence of so many monotypic genera, in such a relatively restricted area, is indicative of the peculiar character of the Antarctic algae. Judging by Papenfuss' (1964) list, the following species are the only ones known to have a wide distribution around the Antarctic Continent :

Monostroma huriotii Gain Geminocarpus geminatus (Hooker fils and Harvey) Skottsberg Desmarestia menziesii J. Agardh D . rossii Hooker fils and Harvey Phyllogigas grandij'olius Rhodochorton purpureum (Lightfoot) Rosenvinge Plocamium coccineum (Hudson) Lyngbye Iridaea cordata (Turner) Bory Leptosomia simplex (A. and E. S. Gepp) Kylin Rhodymenia palmatiformis Skottsberg Ballia callitrichu Phycodrys antarctica (Skottsberg) P . quercifolia (Berg) Skottsberg Polysiphonia abscissa Hooker and Harvey

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As seems true for many other marine organisms, many more species of marine algae occur on the Antarctic Peninsula and on the Antarctic Islands of the Scotia Arc. I n all accounts of algae which follow, the nomenclature, whenever necessary, has been altered to agree with that used by Papenfuss (1964b). Barton (1902) listed five species from Cape Adare. A. and E. S. Gepp (1907) and Foslie (1907b) recorded ten algae from Victoria Land. Lucas (1919) recorded 12 species from Commonwealth Bay. DBldpine and Hureau (1963) reported on some algae from Adelie Land. I n all these cases the material was collected while biologists were primarily concerned with other work. The total flora from these localities is listed below : Chlorophy ceae U ~ o t h r australis ~x Gain Monostroma harioti Chuetomorph mawsoni Lucas Phaeophy ceae Phyllogigas grandifolius Desmarestia menziesi Qeminocarpus geminatus Rhodophyceae Phycodrys antarctica P. quercifolia Iridaea cordata I . mawsoni Lucas Phylloplwra antarctica Leptosomia simplex Plocamium coccineum Kallymenia antarctica Hariot Ballia callitricha Gracilaria dumontioides A. and E. 8. Gepp Spongioclonium orthocladum A. and E. S. Gepp Lithothamnium coulmanicum Foslie

A. Algal ecology and zonation Little of a comprehensive nature has as yet been published on the general ecology and zonation of algae in the Antarctic. Most of what is available is based upon studies of a relatively small area. Hedley (1916a, p. 6) explained that the ice in Commonwealth Bay

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blows out to sea as it forms and so rarely fringes the shore. This aIlows a growth of algae in shallow water. ‘‘ From the surface, as far as the eye can reach down, is seen a jungle of giant algae, among the roots and fronds of which numerous animals of all classes find shelter.” One branching stem found floating on the surface was 18 feet in length (6.6 m). Mawson (1916, p. 268) reported that the MacKellar Islets in Commonwealth Bay were “ kelp-fringed ’’ in December 1913. The larger species represented were probably Phyllogigas grandifolius and Desmarestia menziesi. Skottsberg’s (1941) attempt to classify Antarctic sublittoral communities was severely restricted by lack of material. The work on which it was based was carried out along the Antarctic Peninsula. Three Associations were discussed. 1. Desmarestia Association (0-40 m). Formed mainly by D . harveyana A. and E. S. Gepp but generally with D . anceps Montagne associated. Ice action determines the upper limits but dense growth usually starts in a few metres depth. The usual lower limit is 20-25 m but it may extend to 40 m. Ascoseira rnirabilis Skottsberg occurs fairly commonly in the upper portion of this association, while in the lower sections P~ylZogigasgrandifolius and probably Cystosp~era jacqwinotii come in. 2. Leptosomia Association. The two red algae Leptosomia simplex and L. antarctica (Skottsberg) Kylin are common in shallow water, the fronds attaining a length of 70 cm on occasion. 3. Mixed Rhodophyceae Association. Based only on Skottsberg’s notes the more important members of this deep-water association were Delisea pulchra (Greville) Montagne, Phycodrys antarctica and Plocamium coccineum. Skottsberg also noted Monostroma hariotii, and Lithphyllum aeqmbile (Foslie) Foslie. In a later paper Skottsberg (1953) was able to list 37 species from the Antarctic Peninsula. He showed that the common Desrnarestia from this area should be known m D . menziesii and also listed such forms as: Monostroma hariotii Ulothrix australis Kallymenia antarctica Plocumium coccineum Balliu callitrich

DBlBpine and Hureau (1963) showed a zonation pattern off Petrel Island, Adelie Land. Between tidemarks two distinct bands occurred,

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the upper of Ulothrix australis, the lower dominated by marine diatoms. Below low tide mark there is first a zone of Monostroma hariotii which lower again intermingles with a growth of Gracilaria dumontioides. Below 3 m or so several species of Desmurestia occurred while between 15 and 20 m Phyllogigas grandifolius became common. These large brown algae carried a rich growth of red algae attached to their holdfasts and stipes. Neushul (1965) studied the benthic distribution of algae at several localities in the South Shetland Islands and on the Antarctic Peninsula. I n a protected bay in Half Moon Island, off Livingston Island in the South Shetlands, the shoreline consisted of rocks down to about 5 m followed by sloping coarse black sand. Two species of Desmarestia, D . menziesii and D. anceps grew to large size between the rocks with Ademcystis utricularis on the rock surface. The major animal was the limpet Putinigera polaris (Hombron and Jacquinot) reaching a density of 30 or 40/m2. Algae grew more abundantly wherever any shelter offered. On rocky promontories a wide variety of algae flourished. I n addition to the two species of Desmarestia, Ascoseira mirabilis, Phaeurus antarcticus Skottsberg, Plocamium secundatum (Kiitzing) Kiitzing, Myriogramme margini (Gain) Skottsberg, Ballia callitrichu, Plumariopsis eatoni (Dickie) De Toni, Iriduea obovata Kutzing, Leptosoma simplex, Monostroma and Chuetomorpha were represented. More exposed outer coasts supported an almost pure association of Leptosomia simplex. Associated with the algae on Half Moon Island were the starfish, Granaster nutrix (Studer), Odontaster validus (Koehler) and Neosmilaster georgianus (Studer), the molluscs Philobrya, Lissarca and Patinigera and the crustaceans Serolis, Bovallia and Pontogeneia. Very similar associations occurred elsewhere in the South Shetlands, with long Cystosphuera buoyed up by floats at Harmony Cave. Similar algae associations occurred also at Hope Bay, Melchior Island and Paradise Harbour, all on the Antarctic Peninsula. Phyllogigas grandifolius occurred at Hope Bay but became much more conspicuous in the more southern localities. Wherever suitable rock surfaces occurred algae appeared to continue down below 20 m which proved the limit for observation by diving in this area. Very similar animals were reported by Neushul associated with the algae as those he found on the South Shetlands, with the addition of Margarella (which however occurs plentifully on the South Shetlands also). Etcheverry (1968) reported a predominance of brown algae of the genera Desmarestia, Ascoseira, Cystophuera, Phaeurus and Phyllogigas

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and red algae of the genera Plocamium, Myriogramme and Leptosomia in the sublittoral down to 15 m near the Chilean stations of Arturo Prat and Bahia Paraiso on the Antarctic Peninsula. The benthic and geographical distribution of sublittoral algae in the Ross Sea has been studied by Zaneveld (1966, 1968). I n the upper sublittoral between low water and about 10 m an abundant algal growth even under shore-fast ice 2 or 3 m thick, was developed. The main species were Monostroma hariotii, Hildenbrandia lecannellieri Hariot, Phyllophora antarctica and Iridaea obovata together with Desmarestia willii Reinsch. Between 10 and 37 m the lower sublittoral supported these species (except for D. willii),and in addition Desmarestia menziesi,

Phyllogigas grandifolius, Plocamium coccineum, Leptosomia simplex, and Phycodrys antarctica. Algae continued well below this down to a depth of 668 m (Desmarestia menziesii), the lower limits for the other forms being 478 m (Leptosomia), 312 m (Phyllogigas, Plocamium, Phyllophora and Phycodrys) and 136 m (Hildenbrandia). The only species confined to depths greater than 3 7 m appears to be Ballia callitricha which reaches its lower limit at 312 m and is therefore the only true elittoral species. Zaneveld's field observations showed that transport by floating ice, often postulated as a mechanism for depositing algae accidentally in deeper water off shore, is not an important mechanism in the Ross Sea. Zaneveld also demonstrated a latitudinal distribution of the 11 species concerned along the western shores of the Ross Sea. All the species concerned occurred at 71"s. By about 72"20'S, Desmarestia willii,Phyllogigas, Leptosomia and Ballia had reached their southern limits. By 76"s Desmarestia menziesii and Plocamium had dropped out followed shortly afterwards by Phycodrys leaving Monostroma, Hildenbrandia, Phyllophora and Iridaea. Apart from the green alga Monostroma, the red algae (Rhodophyta) seem best adapted to the cold waters of the Ross Sea. Off South Georgia a rich series of algal associations is found. Although Durvillea and Lessonia are absent, Macrocystis is well developed, and foliaceous Phyaeophyceae such as Aswseira, Phyllogigas and Desmarestia menziesii are abundant (Skottsberg, 1941). Very rich sublittoral communities of Rhodophyceae occur (Skottsberg, 1941, pp. 62-63) with Rhodymenia palmutiformis Skottsberg abundant down to 30 m, Picconiella plumosa (Kylin) De Toni and Plocamium secundatum well represented. Skottsberg (1941, p. 36) believed that from an algological viewpoint South Georgia must be included in the Subantarctic zone, while recognizing that several genera and species linked South Georgia with the Antarctic, and that an endemic element was well represented.

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Much more collecting, with more field observation and some critical systematics must obviously be carried out before the Antarctic marine algae are properly understood. Papenfuss has recently (1964a) made a strong plea for detailed study of properly prepared new material, comparison of these species collected with the types and a re-study of all the published material from Antarctica. Observations on marine algae appear to have been made in a relatively few areas of the Antarctic. They certainly do not appear to be common in many areas, where icescour and the action of anchor ice undoubtedly affect the establishment of shallow-water stands. Papenfuss (1964b) has also recently discussed some of the outstanding systematic problems as regards some of the endemic Antarctic monotypic genera of algae. The large, widely distributed, very typical Antarctic mainland genus Phyllogigas illustrates some ofthese problems. No reproductive organs, the structure of which provide major clues in the classification of algae, have been observed in any specimen yet collected. The genus is therefore considered to be of uncertain systematic position although a special family has been erected for Phyllogigas and an apparently allied (if not identical) genus from South Georgia, Himantothallus. Papenfuss had made a special plea for the collection of large samples of Phyllogigas from any area in which it might be encountered in the hopes of finding reproductive organs, and thus elucidating its life history and proper systematic position. D616pine and Hureau (1963) have pointed out that since specimens have now been collected in January, February, April, May, September, October, November and December without finding fertile fronds it seems possible that reproduction takes place in the Antarctic winters, and collecting samples at this period will be difficult. Papenfuss has also pointed out that the systematic position of Ascoseira, a monotypic genus confined to the Antarctic Peninsula and South Georgia, is similarly uncertain, although here the reproductive organs are known. They are unfortunately so anomalous that they do not fit the recognized patterns.

B. Origin of Antarctic algae Skottsberg (1964) speculated on the origin of the Antarctic algae. During maximum periods of glaciation he believed that the marine algae would be largely destroyed around the continent, but because of lower water temperatures conditions off the present Subantarctic Islands would have offered suitable habitats. The endemic Antarctic genera probably belonged to the Subantarctic zone but moved south as the ice receded.

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The more recent biogeographical history offered no serious problems Skottsberg believed, but threw no light on the ultimate origin of the specially cold adapted Antarctic flora which could not be of geologically ancient age,

VI. BENTHIC ASSEMBLAGES Study of Antarctic sea bottom assemblages is in a fairly primitive state. This probably mirrors a general lack of certainty of approach towards methods of describing and codifying the groupings of plants and animals found on the sea floor in other parts of the world. Biologists seem to have lost confidence in the underlying bases of the ‘‘ community” hypothesis of Petersen, and have tended to use the noncommittal concept of “ assemblages ”, without any real change of technique or outlook. The almost insuperable difficulties in having all organisms identified to a reasonable standard of accuracy within a reasonable period of time, and the acknowledged uselessness of including discussions and measurements based only upon those groups which can be identified, mean that detailed studies of assemblages are only profitable in well settled areas where the biota is well known. What work has been done in Antarctica is at the basically preliminary descriptive stage with quantitative work at a minimum. At the same time the use of self-contained diving apparatus has allowed direct observation to be made down to about 30 m or so, and thus descriptions can be much more accurate. Published work on Antarctic benthic assemblages is at present based upon descriptions of very restricted areas, or if dealing with a larger area is still extremely objective, with few firm identifications, no real assessment of major faunal elements, and little comparison between one assemblage and another. At the same time one must wonder how many years will pass before total faunal lists for major Discovery benthic stations are available, much less the mass of material collected since. The brave authors who have attempted to describe assemblages in the Antarctic probably realize all too well the difficulties involved. What little we know of Antarctic benthic ecology we owe to their efforts. One technique devised for other purposes, but which gives a total quantitative figure fairly rapidly, is the measurement of biomass which has almost become the fashionable measurement to take. Much of what has been published on Antarctic benthic biomass has come from the work of Soviet scientists. Andriashev (1966) has given a summary of this work in East Antarctica. In depths from 100 to 200 m average

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biomass figures were between 1 245 and 1 347 g/m2, while between 200 and 600 m, the average ranged between 239 and 319 g/ma. Andriashev, himself stressed that the highest indices of biomass depend on the presence of sponges, ascidians and bryozoans which may make up t o between 60 and 90% of the total weight. Dearborn (1967) gave a general account of the invertebrate studies carried out in the Ross Sea, and particularly McMurdo Sound between 1958 and 1961. Material was collected using the usual sampling techniques, from ice-breakers and other vessels as opportunity offered. The major programme was maintained through adventitious, or man-made holes in the ice a t McMurdo Sound throughout the year. Grabs and wire traps were the main collecting devices used for the benthos, although trawls were used in cracks, or between neighbouring holes. Accounts of the first years’ endeavours sound very similar to the account given by Hodgson (1907) on methods he used for collecting on the National Antarctic Expedition of 1901 t o 1904. However, the modern collecting methods were more sophisticated and became more so. Huts which could be heated were erected over the main collecting holes, and gradually the collection of material became more of a routine and less of an heroic adventure. Tressler (1964) gave a good account of the hydrographic and biological operations at the later stages (1960-61). The main collecting holes were not static in relation t o the bottom since the ice shelf was gradually and regularly moving. Peckham (1964) recorded the general results of a diving programme throughout a year at McMurdo Sound. His description of the bottom is so graphic that it is worth quoting in full : The benthos of the Antarctic is reputed to be one of the richest areas for sponges in the world. In the shallow waters of McMurdo Sound sponges, along with sea anemones, soft corals, many alcyonarians, and a few stalked tunicates are attached to a volcanic gravel or rock substratum. As the depth increases the biotype changes, with a thick encrusting sponge mat forming the base for other animal attachments. Larger anemones replace the ubiquitous alcyonarians found in shallow water; pterobranches are found and there are other sponges growing on this mat which are nearly 3 feet high and as large in diameter. On the horizontal surface of these large sponges, communities of hydroids and serpulid worms form separate sponge-top biocoenoses. Living in association with this base of sessile fauna are the grazers and scavengers. Sea spiders, some larger than 8 in in diameter, are found on the sponge mat or feeding on coelenterates. The foot-long nemertean worm Lineua corrugatus and the asteroids Odontaster spp. are the major predators

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in this area and were seen in thick mats feeding on the large isopod Glyptonotus antarcticus. Dearborn’s thesis (1965) has not been published and we must rely for short general accounts (1967, 1968) and references to the thesis in sundry publications by other authors, for any official knowledge of it. Since this is obviously the most comprehensive study of a relatively shallow-water high Antarctic habitat, its publication is greatly to be desired. I n the meantime the general accounts do not give enough detail to elucidate the assemblages present. Until Dearborn’s work can be published, and until Bullivant’s (1967) classilication of deeper water assemblages can be clothed in sufficient identifications to make them objective, fine detail or broad generalization is all that is really available. Dayton et al. (1970) as a result of 178 dives in variety of areas in McMurdo Sound have been able to give some picture of benthic zonation in this area. Shallow-water habitats down to 33 m or so are dominated by ice phenomena. Annual sea ice formed to a depth of 4 m or so floats with the tides and scours subtidal areas. Floes from the ice-shelf can continue the scouring action rather less drastically down to about 15 m. Anchor ice forming on the bottom, in sufficient density to form a mat, lifting all manner of benthic organisms and carrying them to the surface seems to form regularly down to 15 m and has been seen down to 33 m. Such animals as the fish Trematomus, the echinoid Sterechinus neumayeri, the sea star Odontmter validus, the nemertean Lineus corrugatus, the isopod Glyptonotus, and several pycnogonids were seen caught in newly formed ice. These authors have recorded twelve Sterechinus and forty Odontaster frozen into a square metre of the sea ice. This ice action apparently produces a marked zonation. Zone 1. Extends down to about 16 m. Ice phenomena seem to clear most animals from this area every year. Those animals which are present must re-colonize the area during the annual ice-free period. Sterechinus, Odontmter, Lineus, Glyptonotus, and a few pycnogonids and fish forage into the area during the summer. A similar group of animals with the addition of Neobuccinum eatoni was recorded from this zone by Pearse and Giese (1966). Zone 11. Except where anchor ice (for one reason or another) cannot form this zone extends from 15 m down to a sharply defined 33 m lower boundary. I n this zone sessile animals are common. The dominant sessile forms are Alcyonium paessleri (alcyonarian), Artemidactirr victrix, Isotealia antarctica, Urticinopsis antarctica and Hormathia

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lacunifera (actiniarians) together with Clavularia franklinianu Roule (stoloniferan)and Tubularia hdgsoni Hickson and Gravely and Lampra parwula Hickson and Gravely (hydrozoans). I n most areas the large ascidian Cnemidiocarpa verrucosa is present. The alcyonarian and the hydroids and sponges feed on suspended particles but the actinarians Isotealia and Urticinopsis are active predators. Both will feed on large medusae which come within range, but Urticinopsis preys predominantly on the urchin Xterechinus which makes up about 77% of the diet of this sea anemone. Dayton, Robilliard and Paine (1970) illustrate the predation of Sterechinus by Urticinopsis in a series of beautifully clear underwater photographs. As in Zone I the most obvious motile animals are Odontaster, Sterechinus, Lineus and the fishes Trematmus bemutcchii and T . centronotus. I n addition three pycnogonids Thaumastopygnon striata (Mbbius), Colossendeis robusta Hoek and C. melalonyx Hoek are also common. A whole series of predator-prey relationships from this zone were noted in this paper.

Zone I I I . Although this zone begins sharply at 33 m, its lower limits have not been observed or measured. The 33 m level seems to be the definite lower limit of anchor ice formation. Here the bottom is covered by a thick mat of sponge spicules and dead bivalve shells, almost always over 1 m thick. The surface supports an almost complete cover of living sponges. The sponges support actiniarians, hydroids, polychaetes, bryozoans and many molluscs, including large numbers of the bivalve Limatula hodgsoni. The sponge spicule matrix contains a very rich fauna indeed. Dearborn (1968) has recorded thousands of small gastropods of the genera Margarella and Subonoba per square metre. The most conspicuous motile animals in this zone are the asteroids Acodontaster hodgsoni (Bell), A. conspicua (Koehler), Perknuster fuscus antarcticus and Odontaster meridionalis (all feeding on sponges), Odontaster validus still largely a detritus feeder, Diplasterias brucei attacking bivalves especially Limatula, and occasional specimens of Macroptychaster accrescens (Koehler) feeding on other echinoderms. A large nudibranch, Austrodoris mcmurdoensis Odhner was often observed eating sponges. The main predatory univalve seemed to be Trophon Zongstafi, which drilled through the shells of bivalves, especially Limatula. It is obvious that this Zone I11 is one in which most inshore collecting has been done by visiting expeditions in the past. It is certainly the " McMurdo Sound Glass Sponge Assemblage " of Bullivant (1967, p. 62) but deserves somewhat more importance than the minor assemblage status Bullivant gives it.

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Dearborn’s collections as reported by him (1967) are obviously mainly taken from Zone I11 of Dayton, et al. On volcanic gravel and debris in less than 50-60 m Lineus, Clyptonotus, Limatula, Ophiurolepis geliclu, Ophiacantha antarctica, Odontaster validus and Diplasterias brucei are amongst the most conspicuous animals. Amongst Crustacea the amphipod genus Orchomenella is well represented, 0. pinguides Walker occurring in shallow water while 0. plebs Hurley and 0.rossi Walker were attracted in their thousands to the bait in traps. Below 100 m other amphipods such as Epimeria macrodonta Walker, Epimeriella macronyx Walker, Eusirus microps Walker and Maxilliphimedia longipes Walker were taken, with the brilliant crimson-marked Emirus perdentatus Chevreux below 500 m. Six species of mysids have been identified from these McMurdo Sound collections together with four species of cumaceans, and a single tanaid species, Nototamis antarcticus (Hodgson), proved to be extremely common down to about 100 m. I n deeper water several species of isopods occurred, Cirolana intermedia Vanhaffen, C . albinata Vanhaffen, Aega glacialis Tattersall and several species of Antarcturus. Amongst the molluscs, a scavenging gastropod Neobuccinum eatoni was often common in shallow waters. The bivalves Laternula elliptica, Yoldia (Aequiyoldia) eightsi and Thrmia meridionalis were common burrowing forms with Limatula hodgsoni burrowing in living sponges or in the matted dead spicules below. The small bivalve Philobrya sublaevis lives attached by a byssus to many other fixed animals. The gastropod Trophon longstafli is another carnivore with the trochoids, Nargarella refulgens and Antimargarita crebrilirulata (Smith) and small rissoids like Subonoba and Ovirissoa occurring in countless thousands. Sponges were present in enormous number and variety, especially hexactinellids with their long siliceous spicules, together with many alcyonarians. The other obvious diverse group represented is the echinoderms. Below 60 m the crinoids Promachocrinus kerguelensis and Anthometra adriani occurred together with two other species. Sterechinus neumayeri was the only sea urchin taken in the vicinity of McMurdo Base although three species of the Abatus complex were also collected elsewhere in McMurdo Sound. Nine species of ophiuroids were collected together with about ten species of asteroids. There has always been considerable discussion as to how so many organisms manage to exist under ice shelves in the Antarctic, especially such extensive areas as the Ross Ice Shelf. I n addition to the mere fact of l i e persisting in the sea under thick ice cover, the problem of energy flow in such environments is of great theoretical interest. Littlepage

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and Pearse (1962) reported on investigations carried out near White Island (about 22 km from the summer ice face in McMurdo Sound) and in the vicinity of the Koettlitz Glacier (about 28 km from the summer open sea). Collections from White Island were made at depths of 43 and 75 m, and from the Koettlitz Glacier at 40 m. Collections from the bottom showed a wide range of animals, including Foraminifera, sponges, hydroids, Alcyonaria, Actiniaria, Nematoda, Ectoprocta, polychaetes, pycnogonids, copepods, isopods, tanaids, gastropods and echinoids. Specimens of the amphipod genus Orchomenella (probably plebs Hurley) were caught in thousands in baited traps. The ice in these areas is thick enough to prevent enough light penetration for diatom production. Animals presumably must rely on detrital material transported under the ice as a primary source of nutrients. Littlepage and Pearse noted that a number of very common shallow water McMurdo Sound animals were missing from these collections, e.g. Limatulu hodgsoni, Odontaster validus, Lineus corrugatus, and Trematomus bermcchii. Wohlschlag later (1964, p. 53) records this latter fish species from beneath the Koettlitz Glacier at Heald Island. A multi-discipline international project is being discussed under the title " Ross Shelf Drill-hole Project ", to investigate the effects of ice cover and isolation from open water on the physical and chemical properties of the underlying sea water and the associated plant and animal life. Preliminary investigations along the edge of the ice shelf were initiated during 1970 at McMurdo Sound. Four benthic communities in moderate depths at the Haswell Islands, near Mirny in the Davis Sea, were described by Propp (1970). 1. On rocky ground from 2 to 10 m a community of diatoms, the sea-star Odontaster validus and the hydroid Tubularia ralphi Bale occur. The diatoms develop a layer several centimetres thick on the bottom in spring and summer. The bottom is covered by anchor ice. Some 20-40 species have been recorded. Total animal biomass reaches between 20 and 25 g/ma, 2. Between 6 and 26 m a community is dominated by the red alga Phyllophora antarctica, calcareous algae and the sea urchin Sterechinus neumyeri. Anchor ice forms to a less extent in this area. The total number of animal species increases to between 40 and 60. The total animal biomass is 460 g/ma. 3. Between 25 and 30m the bottom community is characterized by Alcyonaria. The associated fauna is extremely varied reaching numbers of 70 or 80 species. Total biomass reaches 1 000 g/ma. 4. I n depths below 30 m a community with the sponges Rossella racovitzae and Scolymastra joubini, the hydroid Oswaldella antarctica

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(Jaderholm) and some tunicates together with several hundreds of associated species produces a total biomass of 3 kg/m2. The practical absence of algae (except for Phyllophora) may be an unusual feature in this area. Comparative sampling at Molodezhnaya off Enderby Land was reported by Gruzov and Pushkin (1970). Off Molodezhnaya, in contrast t o the locality sampled off the Haswell Islands, there were extensive muddy and sandy areas. On steep rocky coasts snow drifts on the ice shelves block most of the light. Here the sequence of organisms is much as that recorded at Mirny. The upper zone is lifeless (down to 7 or 8 m). From 8 to 16 m Odontaster validus, Sterechinus neumayeri, sponges and small colonies of the alcyonarian Eunephthya occur. Near low coasts, the ice is fairly transparent and snow drifts are lacking. Here a much greater development of plant life takes place. Below the lifeless zone (2-6 m) a rich growth of diatoms occurs. Below this a zone of algae is well marked with two or three species of red algae extending to a depth of 10 m and the brown algaewith Odontaster validus, Sterechinus neumayeri, sponges, the nemertine Lineus and polychaetes. From 30 to 60m no algae remain but Sterechinus is abundant with sponges, ascidians, alcyonarians, echinoderms, pycnogonids and Crustacea. This zone resembles the sponge community at Mirny. The muddy and sandy habitats were sampled only down to about 16 m. The infauna consisted of the bivalve Laturnda, sea urchins (Abatus sp.) and polychaetes, with Odontaster and some gastropods as epifauna. McCain and Stout (1969) gave a preliminary account of two transect stations near Arthur Harbour, Antarctic Peninsula, selected to show the zonation of benthos on vertical rock faces. The faces were nearly vertical down to about 46 m where they met gently sloping mud. Surf action seemed to extend down to about 16 m, resulting in murky water above this depth. From the surface to 8 m the limpet Patinigera poZaris and encrusting algae were the main organisms present on flat surfaces with the large sea urchin, Sterechinus neumayeri and the brown alga, Desmarestia in cracks and crevices. From 8 to 15 m the dominant organism was the kelp PhyZEogigas grandifolius under the cover of which the isopod, Glyptonotus antarcticus, and many other invertebrates occurred. Below 16 m the rock surface had a heavy silt cover. Some kelp zone animals extended downwards through this zone while gorgonian corals, siliceous-spiculed sponges and nemerteana occurred in the lower limits. Three zones between the surface and about 30 m were therefore distinguished :

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(a) an upper surf zone ; (b) a middle kelp zone ; (c) a lower transition zone between the kelp zone and the mud bottom. From Ardley Bay, near Bellingshausen Station, King George Island, South Shetlands, Gruzov and Pushkin (1970) recorded a sequence which can be compared with that at Arthur Harbour. From 2 m down a zone of algae (green and red representing five to seven species) is developed. The limpet Patinigera polaris is a dominant animal, with starfishes, sea urchins and ascidians, but the fauna is poor. Between 8 and 10 m, brown algae replace the reds, and the seastar Labidimter appears. At about 30m the mud appears. Large colonies of synascidians characterize this zone, together with burrowing sea urchins and ophiuroids. In shallower muds (10 m) the bivalve Laternula and the isopod Glyptonotus are common. The sublittoral zone at Signy Island in the South Orkneys (Price and Redfearn, 1968) supports a rich growth of algae. The large brown algae, Ascoseira, Desmrestia and Phyllogigas live on deeper rock faces, and closer to the surface in crevices. Desmurestia anceps is the common form in the middle, with D. menxiesii in the upper sublittoral. Epiphytic algae growing on these browns include Monostroma hariotii, Adenocystis, Desmurestia ligulata, Ballia and Leptosomia. I n the shadow of the large brown algae is a secondary layer of much smaller species, largely red algae and including Phyllopha, Myriogramme, Ballia, Plocamium and Cystoclonium. Associated with these algae is a wide range of animals. Amongst holdfasts the tubeworms Harmth6e and Neanthes occur, together with the small bivalves, Philobrya and Mysella. Attached to the fronds are the limpet, Patinigera, the univalves Pellilitorina, Laevilacuwria and Laevilitorina and the small bivalve Lissarca. The amount of light appears to influence the development of a crevice fauna. I n areas receiving strong illumination the isopod Glyptonotus and the echinoderms Cryptasterias and Odontaster are found. In deep shade the algae are lacking and are replaced by abundant sponges, tubeworms, a brachiopod and the holothurian Cucumaria. Shallow water sands often support populations of floating algae, in particular Desmarestia anceps, with burrowing bivalves Laternula, Mysella and Yoldia (Aquiyoldia) eightsi, together with polychaetes. Bullivant (1967), as a preliminary report on a survey of the Ross Sea carried out by the New Zealand Oceanographic Institute during

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the summers of 1958/59and 1959/60, listed a number of distinct types of faunal assemblages from the Ross Sea. A good dea1 more work needs to be done before these proposals can gain general acceptance, and much more identified material must be incorporated into the data before Bullivant’s assemblages can be given exactitude. Some identifications from various published sources have been incorporated into the following summary. Four main assemblages were discussed : 1. Deep Shelf Mixed Assemblage ; 2. Deep Shelf Mud Bottom Assemblage ; 3. Pennell Bank Assemblage ; 4. Minor Assemblages.

1. Deep shelf mixed assemblage

Occurring widely in the Ross Sea and in McMurdo Sound on fine sediments through which erratic boulders are scattered. The common animals are tubicolous polychaetes, bryozoans (mostly rooted varieties), occasional gorgonaceans, various ophiuroids, crinoids, and other echinoderms and molluscs. Bottom photographs published by Bullivant (plate 21) showed the general appearance. Animals identified from a range of the stations listed as belonging to this assemblage, but identified after the publication of Bullivant’s paper include : Molluscs : Limatula hodgsoni, Cyclocardia astartoides, Thracia meridionalis, Cadulus dalli antarcticus ; Ophiuroids : O p h i m n t h antarctica, Amphipodiajoubini ; Asteroid : Porania antarctica glabra ; Pycnogonids : Pycnogonum gaini, Ammothea (Ammothea)glacialis, Achelia (Pigrolavatus) spicata (Hodgson), Austroraptus polaris Hodgson. 2. Deep shelf mud bottom assemblage

Occurring at deeper stations on the shelf on a substrate of mud, or sandy mud, together with erratic boulders. Tubicolous polychaetes are common, with two species of sipunculid worms (Boljingiamargaritacea capsiformis and B. andersonni), the arenaceous Foraminifera, R h b damminu, various ophiuroids particularly Amphipodia joubini, but including Ophionotus victoriae Bell, holothurians particularly rat-tailed species, and Umbellula sp. Animals subsequently identified from these stations include the pycnogonids, Colossendeis lilliei, and C. megalonyx megalonyx, the coral Plabellum impenaum, the mollusc Dentalium mujorinum, and the asteroids, Bathybiaster loripes obeaus, Psilaster charcoti, hidaster gerlachei and Notasterim armata Koehler.

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Bullivant (1967, plate 13) illustrates the bottom at one of the stations. 3. Pennell Bank assemblage

Here the substrate consists of cobbles up to several centimetres in diameter embedded in a muddy sand, with patches of muddy sand between the cobbles. Attached animals such as calcareous bryozoans, gorgonians, tunicates and stylasterine corals were common. Animals identified subsequently included : Corals : Flabellum impensum, Caryophyllia antarctica ; Ophiuroids : Uphiacantha antarctica, Ampfiiura belgicae, Ophioceres incipiens, Ophiurolepis gelih ; Asteroids : Peribolaster powelli H. E. S. Clark ; Ppnogonids : Achelia (Pigrolavatw) spicata, Colossendeis lilliei. Bullivant (1967,plate 17) provides a bottom photograph which illustrates the appearance of this assemblage. 4. Minor assemblages (a) Shelf Edge Barnacle Assemblage

This assemblage develops on the outer edge of the deep shelf between 360 and 600 m. Living barnacles (Bathylasma corolliforme, previously

known as Hexelasma antarctica) cover the exposed rocks, around which the accumulating dead barnacles have built up an almost homogeneous substrate of dead barnacle plates. The coral Blabellum impensurn also occurs here. (b) Deep Ooze Assemblage

A sparse fauna developed in a diatomaceous ooze occurring from 1 200 to 2 200 m. (c) Deep Slope Cobble Assemblages (i) Stylasterine coral assemblage at 322-368 m with the stylasterine coral Errina, and the scleractinian corals, Flabellum impemum and F . antarcticum. (ii) Gardineria antarctica Assemblage, developed between 461 and 591 m, dominated by the solitary scleractinian coral Gardineria, to-

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gether with Plabellum antarcticum, and the pycnogonid Pycnogonum

gaini . (iii) Brachiopod Assemblage, in 828 to 1 335 m. (d) McMurdo Sound Glass Sponge Assemblage This assemblage develops on a substrate of unsorted rock debris on which siliceous sponges,especially Rossella and Cinachyra are particularly common. The bivalve Limatula hodgsoni is also common. Other organisms recorded are the starfish, Odontaster meridionulis, and the pycnogonid, Achelia (Pigrolavatus) spimta. The surface appearance is given in a bottom photograph (Bullivant, 1967, plate 16). (e) McMurdo Sound Mixed Assemblage Bullivant (1967) indicates that this assemblage may be a variant of the Deep Shelf Mixed Assemblage. The substrate is a mixed sediment with a high proportion of coarse rock particles. Siliceous sponges are particularly common in the shallower manifestations of this assemblage. The free-living crinoid Promachocrinus kerguelensis is apparently common, as are the molluscs, Cyclomrdia astartoides, Thracia meridionalis, Limatula hodgsoni, Notochiton mirandus and Trophon.

(f) Ross Sea Bathyal Assemblage Occurring in the basins exceeding 1 000 m in depth north of Ross Island and in Terra Nova Bay. Kennett (1968) discussing the distribution of Foraminifera from these same Ross Sea stations found a general correlation between his microfaunal assemblages and the macrofaunal assemblages described by Bullivant . I n general the calcareous foraminiferal assemblages occurred in association with Bullivant’s Pennell Bank, shelf edge barnacle, stylasterine coral, Gardineria antarctica, brachiopod, McMurdo Sound mixed and McMurdo Sound glass sponge assemblages and in part with the Deep Shelf mixed assemblage. Arenaceous foraminiferal assemblages occurred together with the Deep Shelf mud bottom and Deep Ooze assemblages and in part with the Deep Shelf mixed assemblage.

A. Bottom photograph One of the newer techniques to be brought to bear on studies of the benthos is that of bottom photography. Bullivant was responsible for a set taken in the Ross Sea and has published some of these (Bullivant, 1959b, 1961,1967) as have Dell (1965), Fell (1961) and Clark (1963). A

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very large number of bottom photographs obtained on Cruises 32 to 36 of the Eltanin in 1968 have been published by Jacobs, Bruchhausen and Bauer (1970). Ozawa, Inoue, and Oshita (1968) have published a few from off Scott Island and off the Balleny Islands. From a biological point of view, the values to be obtained from bottom photographs are fairly general. They serve to confirm the type of assemblage being sampled by dredges or trawls, to give general impressions of wider areas with occasional animals visible. Unless sampling, and probably reasonably extensive sampling, is carried out in the same area as the bottom photograph no certain identification can be made of organisms visible in the photographs. However, when sampling and photography are carried out in the same area, additional and unsuspected results may well be obtained. The deductions made by Fell (1961) on the feeding habits of ophiuroids in the Ross Sea, primarily on the evidence presented in bottom photographs is a good case in point. Similar additional biological facts were deduced by Newman and Ross (1971) from bottom photographs showing barnacles.

VII. BROODING OR VIVEARITY

ANTARCTIC ANIMALS The habit many Antarctic animals have acquired of brooding or protecting their developing young has been mentioned often in the literature. Examples have been recorded previously in this work. Apart from groups like the Isopoda where the habit is widespread and bivalve families such as the Philobryidae in which it appears universal, the habit in Antarctica seems to be most strongly developed in the Echinodermata. IN

A. Echinodermata The brooding habit is conspicuous amongst Antarctic holothurians. At least 15 species (out of a total fauna of 38) have large yolky eggs and brood their young. Holothurians with this habit either hold the developing young on the dorsal or ventral surface of the body, or carry them in special pouches or pockets (Pawson, 1969a). Over 50% of Antarctic comatulids brood their young in some manner, this percentage being very high. Some 600 comatulids are known from other areas, and onIy about 1% of these are viviparous. An important exception in the Antarctic is the subfamily Heliometrinae, which includes the three most abundant species of Antarctic crinoids (Dearborn and Rommell, 1969). Most echinoids pass through a pelagic larval stage-the echinopluteus. I n Antarctic echinoids development is often direct with the female brooding the developing eggs. In the cidaroids the young are

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brooded on the peristome or in the vicinity of the periproct. In the spatangoids, especially the genus Abatm, the eggs develop in the sunken dorsal petals. The brooding habit in asteroids is well known but the statistics for Antarctic species are not well recorded. Ludwig (1903) listed 11 Antarctic and Subantarctic species. Fisher (1940) believed it Iikely that all species of Pteraster, Euretaster, Diplopteraster and Hymewter brood their young, together with many species of Leptychmter and Henricia. The habit has been observed in the genera Kampylaster, Rhopiella, Odinella, Anasterias, Lysasterias, Diplasterias, Cryptasterias, Neosmilaster and Crranaster, and probably occurs in Mirmtrella, Anteliaster and Pealidaster (Fisher, 1940). Mortensen (1937) concluded that at least 50% of the ophiuroids of the Antarctic and Subantarctic regions are viviparous. At that time only 52 species anywhere in the world had been shown to be viviparous, and 31 of these came from the Antarctic-Subantarctic. Mortensen also pointed out that the overwhelming majority of the viviparous ophiuroids were hermaphrodite, and that not a single non-viviparous ophiuroid was known to be hermaphrodite. There is also a strong tendency in these viviparous Antarctic ophiuroids, for development to take place in the ovary rather than in the bursae (as is more usual elsewhere). An explanation for these facts is difficult to find. It can hardly be a direct response to a cold-water environment since there are relatively few viviparous forms in the Arctic regions. Fell (1945) has, however, shown that direct development is much commoner in the echinoderms in general than had been believed, and that 63% of the New Zealand ophiuroid fauna then known showed direct development. He also argued that judging by the evidence of large, yolky eggs, perhaps 70% of the Antarctic ophiuroids have direct development. Fell’s general conclusion was that indirect development was not the “ typical ” development in echinoderms, “ but that the kind of development followed depends on the particular conditions obtaining in each species ”. From the evidence available to him, Fell believed that, “ a yolky egg is a condition frequently associated with viviparity ”. The young brittle star produced by viviparous species is able to pursue its development to a much more advanced stage before it is released into the general environment. As Fell showed it is highly probable that additional food material may be absorbed from the adult while the developing young are retained in the bursa. Granted therefore that viviparity may be much commoner in echinoderms generally than has been believed, it seems highly probable that species exhibiting viviparity would be at a selective

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advantage in Antarctic waters where planktonic food material is extremely seasonal in production. B. Mollusca Several writers have commented upon the fact that a relatively large percentage of Antarctic bivalves retain the young within the mantle cavity until a definite shell is formed. Pelseneer (1903) noted the habit in a few species. Burne (1920) recorded the incubation of eggs either in the mantle cavity or in the gills of Adacnarca and Laternula. Soot-Ryen (1951, p. 42) commented, “ It is a striking fact that nearly all the more littoral species, here considered to be old inhabitants of the Antarctic region, are ovoviviparous. . . . These conditions are observed in the families, Philobryidae, Gaimardiidae, and Cyamiidae, in many genera of the superfamily Leptonacea, in some Carditidae and by Laternula ellipticu. The reproduction of Thracia meridionalis and Adamussium colbecki is not known.” The incubatory habit has been definitely recorded in the following species : Philob~yasublaevis (Soot-Ryen, 1961; Dell, 1964b, up to 175 developing eggs); Philobrya cupillata (Dell, 1964b, up to 400 young shells) ; Adacnarca nitens (Burne, 1920; Soot-Ryen, 1951; Dell, 1964b; Nicol, 1966); Lissarca notorcadensis (Dell, 1964b); Lissarca miliaris (Soot-Ryen, 1951); Kidderia bicolor (Soot-Ryen, 1951); Gaimardia trapesina trapesina (Lamarck) (Pelseneer, 1903); Mysella arthari (Cooper and Preston) (Dell, 1964b); Pseudokellya cardifwmis (Pelseneer, 1903); Cyamiocardium crassilabrum (Dell, 196413, up to 44 developing eggs) ; Laternula ellipticu (Burne, 1920); Cyclocardia astartoidee (Probably).

The habit has been observed in many other members of the family Philobryidae and is probably universal in the family. The habit is thus comparatively common in Antarctic bivalves in contrast to its relative scarcity in non-Antarctic members of the group. All species of Philobrya apparently brood their eggs. Burne (1920) showed that in Anutina (=Laternula) ellipticu a specially enclosed supra-branchial chamber exists, “ roomy enough to provide accommodation for a very considerable mass of eggs ”. This feature is also

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known in some other members of the family such as Myochuma and Cochlodesma but was not known to Burne in any other species of Laternula. I n the Montacutidae, Montacuta bidentata (Montagu) and M . ferruginea (Montagu) incubate the eggs for some time but veligers are released so that there is a restricted pelagic larval life (Thorson, 1946). Cyamiocardium dahli Soot-Ryen from Chile is another species in this genus which incubates the eggs (Soot-Ryen, 1951, p. 46). Probably many additional species in the Antarctic will prove to have a similar habit when more is known of their biology. In order to interpret this phenomenon properly, much more will need to be known of the reproductive habits of non-Antarctic members of these families. It may be noted that all the species listed above except for Mysella arthuri and Cyamiocardium crassilabrum have achieved wide dispersal so that the incubatory habit in itself is no barrier to possible dispersal and may be a distinct advantage as regards establishment of a species in a new area.

C. Ascidiacea Kott (1969a)discussed the incidence of viviparity amongst Antarctic ascidians. The families Styelidae, Molgulidae and Agnesiidae, and the subfamily Polyzoinae, amongst which there are many viviparous species in general, are well represented in the Antarctic. The members of the suborder Aplousobranchia are generally viviparous, but some Antarctic species such as Synoicium adareanum (Herdman) and s. georgianum (Sluiter) retain the larvae until they metamorphose within the adult test. Species of the suborders Phlebobranchia and Stolidobranchia, members of which are not usually viviparous, have also acquired this habit in Antarctic waters.

D. Polychaeta Gravier (1911d) discussed some examples of incubation of eggs in polychaetes collected by the Second French Antarctic Expedition. In Eteone gaini Gravier, the eggs form a compact mass tightly enclosed between the lateral and ventral aspects of the worm, where they are enclosed by a membrane secreted by the animal. I n Flabelligera rnundata Gravier, the anterior part of the body is enclosed by curved, long bristles which form a kind of cage. Inside this, between the palps and gills, the eggs are deposited in groups. Hartman (1967~)described the peculiar breeding habit of the tube dwelling Nothria notialis (Monro). Some of the tubes collected contained lateral capsules, with a single adult in the main tube and juveniles at various stages of development in the lateral capsules. This is in contrast

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to the habit in Paronuphis antarctica (Monro) of laying the eggs in one clutch within the tube, where the developing young remain (Hartman, 1967~).It appears that a pygmy male is fixed to the female in this species. Potamethus scotiae (Pixell) (a sabellid) was found to incubate eggs within the tube, as does Onuphis paucibranchis (Ehlers).

E. Nemertea Joubin (1914) recorded what appears to be the first instance of egg brooding in the Nemertea. In a species described by Joubin as Amphiporus incubator from Petermann Island, the females construct a cocoon around themselves and seal it off. The eggs are laid inside the cocoon. A most peculiar mechanism has been developed for fertilization which in all other nemerteans is external. As the developing eggs swell inside the female they gradually push out until they perforate the skin and present a small surface of the egg membrane to the outside sea. At this stage fertilization occurs. About a hundred eggs are laid in the cocoon. On hatching the young worms crawl on the inside eating egg membranes and other food materials excreted by the female when the eggs are laid. The evidence seems to show that the female does not survive. An allied species, Amphiporus michelseni Joubin also incubates its eggs but in much simpler fashion. The female secretes a parchment tube open at both ends, in which the eggs are laid.

F. Reasons for incidence of viviparity Discussions on the high incidence of viviparity amongst Antarctic animals have usually been confined to the consideration of one group of animals. A major difficulty in seeking to explain why viviparity is so common in the Antarctic is that in general viviparity is not as well marked in the Arctic. It cannot therefore be envisaged as a natural response to cold water or “ difficult ” ecological conditions. The whole concept of “ difficult ” conditions in the polar regions must surely derive from an anthropocentric viewpoint. No biologist aware of the great diversity of life in Antarctic waters, the enormous bulk of organic matter produced, and the close adaptations that have been made to the main physical cyclic changes throughout the year, can surely believe that this is not a “ successful ” biota. Rather than “ difficult ”, the environment must be almost perfect for those organisms which have adapted successfully to it. Wohlschlag’s work on the physiology of Antarctic fishes almost indicates that Antarctic animals may be adapted

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even more efficiently to their environment than are animals in temperate or tropical waters. It is not difficult to find differences between Arctic and Antarctic conditions, it is only difficult to find differences of sufficient scope to explain differences in the incidence of viviparity or brood protection. Nor is the difference in incidence always marked. Hedgpeth (1969b) for example, has noted that in some Arctic forms of the pycnogonid genus Nymphon, the males actually carry the developing young about until they are quite large. This habit has not been observed in any species of Nymphon in the Antarctic. Hedgpeth believes that this may be because the more abundant food available in the Antarctic makes such a degree of parental care unnecessary. Such asimple explanation ignores the many other cases of brooding and parental care amongst Antarctic animals. It seems to the writer that a basic fallacy in seeking explanations of this Antarctic phenomenon stems from the method of proposing the problem in the form, " why should this habit be developed by Antarctic animals? ". A more fruitful line of enquiry might well result from considering the problem from a different viewpoint such as, " why have animals with a capacity for viviparous development been able to invade Antarctic waters so successfully?'' or " why does the capacity for viviparous development give so many Antarctic animals an adaptational advantage? ". Changes of viewpoint in regard to the position of direct and indirect development amongst the echinoderms has been outlined above. Direct development may be more widespread than indirect. At least it is an important method of reproduction. It may be significant that the ophiuroids in which the habit is well developed outside the Antarctic are one of the most successful groups in the Antarctic, and that the best represented Antarctic groups amongst the echinoids are the cidaroids and the spatangoids in which brooding, especially amongst Southern Hemisphere members is reasonably common. The writer (Dell, 1962) has shown that brood protection occurs much more commonly amongst chitons than had been thought previously. The Antarctic-Subantarctic occurrence in such forms as Hemiarthrum setulosum is not therefore such an unusual occurrence. It seem8 likely that no group that does not show some degree of viviparity amongst its members elsewhere develops the habit in the Antarctic. Even the 1 % of comatulids outside the Antarctic quoted by Dearborn and Rommell (1969) as being viviparous is significant. Some groups which generally have viviparity as the main method of reproduction have adapted themselves extremely well to the Antarctic. The

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most outstanding examples are probably the isopods, amphipods and cirripedes, and the philobryid bivalves. An investigation of the adaptational advantages to be gained by animals reproducing viviparously could be a valuable study. It is extremely likely that the relatively restricted period of phytoplankton production in Antarctic waters gives advantages to animals that can adapt themselves to a period of abundant plankton food followed by a longer period when food must be sought elsewhere, or where reserves can be utilized. There is evidence that a number of the life histories already investigated do in fact conform to this type of rhythm. A viviparous life cycle is obviously easily adapted to such a cycle. It is sometimes intimated that by evolving a viviparous life cycle, or a brooding period in the life cycle, the animal concerned sacrifices the ability to disperse itself widely. This is another example of human Iogic to which most of the animals concerned do not subscribe. Many of the animals which protect their eggs and developing young most effectively and for the longest time have achieved the widest distribution pattern, often including some of the most isolated islands of the Subantarctic, such as Kerguelen, within their ranges. Against all logic, therefore, animals which brood their young have often achieved the widest distribution patterns. Such dispersal success is easily enough understood when the animal concerned is a bivalve like Philobrya or Gaimardia which normally attaches itself to algae and can achieve its dispersal by passive means. The significance of such a bivalve arriving in a new area with several hundred well-developed young ready for release is obvious enough. When the animal concerned lives buried in the substrate or fixed to rocks, it is only the method of dispersal which has become difficult to envisage. One of the best examples known to the writer is the small chiton, Hemiarthrum setulosum, which has been discussed by the writer (Dell, 1964). This chiton has been recorded from the Crozets, Kerguelen; Heard, and Macquarie Islands, southern Chile, Magellan Strait, South Georgia, the South Orkneys and the Antarctic Peninsula, a familiar enough Antarctic-Subantarctic distribution pattern. Hemiarthrum lives firmly adhering to rocks and broods its eggs and developing young under the protection of the adult shell until they are small replicas of the adult. It normally lives attached to rock in shallow water and has never been reported attached to algae, or even to other molluscs such as mussels which could in turn be attached to algae. Such a species must be distributed as an adult or subadult, by a combination of circumstances which must be moderately rare, when suitable rocks to which the chiton is adhering are torn away by attached algae and

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successfully float from one island to another. Rare though the dispersal method must be, the chiton has achieved a very wide distribution. Perhaps the ability to arrive in a new locality with a number of welldeveloped juvenile specimens is of more importance in achieving dispersal, than a floating larval stage. It seems extremely unlikely that there is a single factor which will explain why brooding of young is so common in Antarctic seas. Some of the reasons may well be found in the past geological history of the area.

VIII. BIPOLARITY Hedgpeth (1970) stated, “ This perennial favourite of biogeographers dies hard ”. Unfortunately this will probably not be the epitaph for the topic of bipolarity, the concept that some species occur in Arctic and Antarctic waters as a kind of relict of a once widely dispersed fauna, which has been replaced everywhere except in the two polar regions. The topic has captured the imagination of writers on semi-popular biology and far too many scientists have devoted their efforts to listing examples of bipolarity, or to providing explanations to avoid the “ relict ” hypothesis. Peculiarly enough, now that the hypothesis itself has no adherents, bipolarity seems to have taken on an importance of its own. Hedgpeth (196984 reviewed the argument by D’Arcy Thompson (1898) who had shown that even at that date the number of supposedly bipolar species was comparatively insignificant in relation to the total fauna, and had indicated that many of these species would be shown by critical comparison to be different species. Both lines of argument are even more apposite today. Groups in which bipolarity is still considered to occur are on the whole “ difficult ” groups systematically. Thus Koltun (1969, 1970) recognized three bipolar species of sponges from an Antarctic fauna of 300 Antarctic species. Amongst sipunculids Edmonds (1969) rather cautiously accepted seven species as bipolar. The priapulids have been considered to present good examples of bipolarity. Better collections and more critical systematics have shown that priapulids are much more widely distributed in deep water, and that most of the other “ species ” concerned differ in each polar area (Lang, 1951 ; Murina and Starobogatov, 1961 ; van der Land, 1970). There appear to be no bipolar species of brachiopods (Foster, 1969), stylasterine corals, scleractinian corals, benthic molluscs, benthic pycnogonids or benthic fishes. The identification of an anomuran crab from the Antarctic as Paralomis spectabilis known previously from off Greenland and Iceland (Birstein and Vinogradov, 1967) is one of the

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few recent examples to be brought forward. The small free-living hydroid, Boreohydra simplex recorded from muddy substrates in northern Europe and South Georgia (Westblad, 1952) will surely be collected in intermediate localities.

IX. ORIGINSOF THE ANTARCTIC BIOTA Unfortunately the direct evidence for the origins of the Antarctic fauna and flora is extremely poor for the Tertiary, which is the geological period from which evidence would be most useful. All other evidence is indirect, being based either upon geological deductions regarding climate, derived from many sources, or upon deductions based on the present faunal and floral elements. The earlier geological history of Antarctica probably bears little relationship to the existing fauna. A rich Cretaceous marine fauna in West Antarctica indicates an environment of temperate to cooltemperate climate. None of the Mollusca present appears to be related to any of the present Antarctic fauna, although there are discernible relationships with living forms from the Subantarctic and farther north. Similarly the echinoderms represented in these beds no longer survive in the Antarctic (Lambert, 1910). Lower Miocene beds from West Antarctica contain fossil penguins and a " cool " molluscan fauna (Adie, 1970). None of the Mollusca seems to be identical with existing forms. Smith Woodward (1908) identified six teleost vertebrae centra from the Tertiary of Seymour Island as belonging to Notothenia. The Notothenioid fishes have thus been in the area for some 30 million years. The echinoid genus Schixaster occurs in the Eocene of Snow Hill Island (Lambert, 1910). Schixaster is closely related to the living Antarctic schizasterid genera, Abatus, Amphipneustes and Tripylus. However, the family Cassidulidae represented in the same beds no longer occurs in Antarctic waters. Discussing the geological history of the Cirripedia in the Antarctic, Newman and Ross (1971) concluded that in spite of the extensive Cretaceous and Tertiary faunas, no genera or species known as fossils have survived except for the Pleistocene Bathylasma corolliforme. Based on a study of palaeomagnetically dated deep-sea cores spanning some four and a half million years, Hays (1970) presented an extremely useful time scale for the last few million years. Present conditions result in a belt of terrigenous deposits around the Antarctic Continent (and extending generally to the limit of pack ice) followed by a beIt of diatom-radiolarian ooze (which extends as far north as the Antarctic Convergence). These two zones have fluctuated northwards repeatedly in the last 400 000 years, the ooze beginning to be deposited A.Y.B.-lO

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about 2 million years ago. Hays believes that on this evidence glaciation began about 4.5 million years ago, and that there have been two periods of rapid cooling since then, one at about 2.5 million years ago, the other at 700 000 years ago. From a study of Radiolaria in sea bottom deposits, Hays (1965) concluded that the Antarctic Convergence could have shifted north by about 5' of latitude during glacial maxima. It seems certain therefore that gradual cooling set in about midTertiary, and that the Antarctic Continent has not been free of ice since this period of refrigeration set in. The general hydrological conditions existing today would probably be initiated once ice shelves dominated the edges of the Continent, and began to produce the cold Antarctic Bottom Water. Adie (1963) considered that problems connected with the distribution of faunas and floras of the Southern Hemisphere fell into two clearcut periods, the first before the Cretaceous, and the second, after the Cretaceous. Although there may well have been suitable connections between South America and Antarctica through the Andean geosyncline in the Carboniferous, this connection does not appear likely to have influenced the existing fauna. However, since the early Tertiary there appears to have been some form of connection between South America and Antarctica through the Scotia Arc (Adie, 1963). Some Antarctic groups appear to be of relatively ancient origin. The ophiuroid genera differ markedly from genera in other parts of the world. The evidence points to a long evolution in comparative isolation during the Tertiary (Fell, 1961). The cidarid ecninoids originating in the Palaeozoic have shown slow rates of evolution throughout their history. However, the subfamily Ctenocidarinae has developed in the Antarctic. Pawson (1969a) considered that the only close relationship of the Antarctic holothurian fauna with any Subantarctic area was with southern South America. The generic composition lends credence to the belief that the Antarctic fauna has been built up by those forms which could tolerate low temperatures, and which could enter the area from South America. Some of these elements may have been derived ultimately from the Indo-Pacific or even the New Zealand area with the assistance of the West Wind Drift. Two opposing views have been advanced regarding the origin of the Antarctic crinoids. Marr (1963) suggested that the high Antarctic forms probably originated on the shelf, the evidence being largely based upon the circumpolar distribution of such endemic species as Promachocrinus kerguelensis. On the other hand, John (1938) believed that

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the fauna originated on the southern extremity of South America. Judging by the evidence from other groups it seems highly probable that both views will prove to be partly true. The outstanding feature of the Antarctic fish fauna is the almost overwhelming part played by the superfamily, the Nototheniiformes. The diversity of habit shown by the members of the superfamily, the fact that one family has acquired the unique feature of whitebloodednew, and the unique mechanisms developed for cold adaptation all bear out the contention of Regan (1914b), Norman (1938) and Andriashev (1965) that this group could only have developed in an area that was isolated fairly effectively probably throughout the Tertiary. The four Antarctic families of the Nototheniiformes, together with the Muraenolepidae make up an old endemic element, possibly with long term connections with South America (Andriashev, 1965). The Congiopodidae represent a later invasion by a widespread Southern Hemisphere family. Its occurrence together with occasional representatives of such families as the Rajidae and the Bothidae is not surprising, although the few families so represented is unusual. The Antarctic members of the two primarily boreal families, Zoarcidae and Liparidae, have obviously been derived immediately from southern South America. Another faunal group has obviously been derived from widely distributed deeper water families, e.g. the Macruridae and Brotulidae. Andriashev (1966) concluded his discussion of Antarctic fish origins, Thus, by its ancient roots and t o a lesser extent by modern influence the Antarctic fauna of bottom fishes is connected with the coldtemperate (subantarctic) South American fauna. Considerably weaker are the links with the New Zealand fauna. . . . There is practically no relation to other regions of the southern hemisphere ”. The above statement relating t o fishes could be repeated with slight variations for group after group of Antarctic organisms. An ancient element which may have developed into a single endemic genus or species, or which occasionally has radiated into numerous species, genera, or much more rarely endemic families, has often established itself widely within the confines of the Antarctic Continent. More recent invasions may show more obvious, and more recent relationships with southern South America, or with the more widely dispersed Subantarctic Islands. Only one great migration route may have existed into Antarctica, and out of Antarctica, throughout the Tertiary in the form of the Scotia Arc. This should never be envisaged as a great broad highway along which South American species marched in their steady echelons into Antarctica. The Scotia Ridge has probably always acted as a filtering ((

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mechanism supplying a possible route for some forms occasionally, and never quite effective enough for other forms to achieve dispersal by this means. Distances between shallow water areas, direction and strength of ocean currents, and fluctuating temperature differentials would provide a series of variables to match the varying facilities for dispersal

FIQ.17. Existing dispersal routes into Antarctica based upon ocean currente and the islands of the Scotia Aro. The same mechanisms allow Antarctic species to reach the Magellan region through the Scotia Arc, and then to be dispersed by the West Wind Drift.

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inherent in Southern Hemisphere plants and animals. Given the periods of geological time involved, the Scotia Arc could supply a differential dispersal route in both directions between the Antarctic and South America and thus to the Atlantic and Pacific Oceans. The other great dispersal mechanism available in the southern part of the Southern Hemisphere is the West Wind Drift (Fig. 17). This is also an obviously highly differential migration route, with longer distances between land masses but perhaps a more certain method for species which can utilize a passive form of dispersal. The West Wind Drift has also probably been in operation through the Tertiary. The fact that the latitudinal belt through which the West Wind Drift has operated may have fluctuated, would only have served to make this more effective as a dispersal mechanism. Two studies supplying statistical data on the effectiveness of the West Wind Drift have been those of Holdgate (1960) in relation to the marine fauna of Tristan da Cunha, and of Fell (1962) in relation to echinoderms. For such organisms as have been able to utilize the mainly passive dispersal methods supplied by the West Wind Drift, circum-subantarctic distribution is possible. By reaching southern South America any such species can be tested by the filter of the Scotia Arc. Similarly any Antarctic species which have reached southern South America, the Falklands or South Georgia by a northward migration may be dispersed through the Subantarctic by the West Wind Drift. Thus any Southern Hemisphere species with the necessary mechanisms for dispersal by the West Wind Drift, over the period of time available through the Tertiary, could have been recruited to the Antarctic biota by utilizing only those dispersal mechanisms which are in operation at present. Similarly Antarctic organisms which are not strictly stenothermal, and which have the necessary dispersal mechanisms could also have been distributed to the Subantarctic islands. Much of the Antarctic fauna seems adapted to live over a wide depth range, and a high percentage of the fauna is found in depths considerably deeper than is usual in other parts of the world. Biogeographers have therefore legitimately postulated that some of the Antarctic fauna may have been derived from adjacent deep-water areas, or that it could have migrated to Antarctica along the series of roughly radiating ridges, especially the Kerguelen and Macquarie Ridges, even though these are too deep to be considered as possible migration routes for normal shelf animals. Dawson (1970) has shown that the Macquarie Ridge provides only the most tenuous link between Macquarie Island and the Antarctic for echinoderms.

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Recent work on the material collected from the Antarctic deep-water basins by the Eltanin have indicated that these faunas form a faunal entity with little direct relationship to the Antarctic fauna (Newman and Ross, 1971; Kott, 1969a; Hartman, 1967b). Consideration of the depth ranges of Antarctic benthic animals shows a similar pattern for many different groups. A very small element is confined to the shelf, while a large number of species is found in archibenthal (or bathyal) depths. At the same time a large number of forms show wide depth tolerances across the shelf and slope. One is tempted to postulate a possible history of a fauna with these elements, and is confronted with the almost inescapable conclusion that the shallow-water element was almost completely eradicated at the height of Pleistocene glaciation. It is amongst the remaining shallow-water molluscs that some of the " old " elements still occur, e.g. Adamussium, Laternula elliptica, Yoldia (Aequiyoldia)eightsi and Neobuccinum eatoni. Similar examples can be cited for other groups, e.g. Glyptonotus (Isopoda), Xterechinus neumayeri (Echinoidea). It is probably premature to pursue any further the question of the origins and relationships of the Antarctic fauna. Too few of the collections made since the I.G.Y. have been written up, and those which have been raise so many new lines of evidence, that speculation at present seems unwise. One of the most productive " studies " for Antarctic biogeography would be an analysis of the distribution of plants and animals along the islands of the Scotia Arc and into the Antarctic Peninsula at one end and into the Magellan Region at the other. Even full studies on the distribution of single well represented groups of animals would be indicative, but studies involving all possible groups would be most valuable.

X. CONCLUSIONS The writer (Dell, 1968, p. 116) has stressed some of the difficulties encountered in working with Antarctic Mollusca. These difficulties are probably equally true of other groups but accentuated in the case of the Mollusca by the bulk of the contributions. First, expeditions have usually been nationally inspired and financed, the countries mainly concerned being England, Scotland, France, Germany, Belgium, Norway, Sweden, the United States, the Soviet Union, Argentina, Australia, and New Zealand. Science may be international, and science in the Antarctic is demonstrably so, but the publication of biological results has certainly tended to be national. A t the peak periods of expedition activity one detects a rivalry to achieve prior publication that goes beyond the bounds of being healthy. How-

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ever, more than in almost any other area the results of Antarctic biological research have appeared in a wide range of languages and in an extremely wide range of scientific journals and expedition reports. One other concomitant result is that the type specimens of Antarctic animals are scattered through the national museums of the world t o an extent that is hardly comparable for any other geographical area (except perhaps South America). This undoubtedly hampers comparison of type specimens and this has proved highly necessary for many Antarctic forms. The concept that Antarctic species might be widely distributed both around the continent and into the Subantarctic has been slow to develop. One suspects that some early workers envisaged the Antarctic as it appeared on a Mercator’s projection of the world. Be that as it may many workers seem to have been over-awed with the distances between Antarctic localities without realising the general uniform conditions. It is also painfully obvious that some workers have been completely oblivious of the sheer bulk of literature on the Antarctic that already exists. Perhaps none of these reasons accounts for the distinguished worker on Mollusca who in the early days of biological work in Antarctic waters (1906) managed to describe the same species under three separate specific, and two different generic names, all from the South American quadrant, and all in the same year. Fortunately more general reviews on specific groups of animals are now appearing and there is now little excuse for lack of knowledge of the literature. Another difficulty in the study of any particular benthic group is undoubtedly the large gaps in collecting around the continent and t o the north. Distribution maps for even the commonest, most widely dispersed species really only delineate the human collecting effort rather than any other biological fact. Even for such important areas as the Scotia Ridge, collections are as yet too restricted to allow for detailed analysis of this area as a migration route. Even when most of the available collections have been written up it still does not seem that enough detailed information will exist t o show, for example, how many species show a direct link between the Magellan Region and the South Shetlands and the Antarctic Peninsula without also occurring a t the South Orkneys and South Georgia. I n addition to collections from the obvious areas around the Continent t o fill distribution gaps and very detailed coverage of the Scotia Ridge it would be extremely useful to have a few studies of faunal change with depth in rather more detail than is a t present available even from such well-worked areas as the Ross Sea.

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The great need is still indisputably for faunal monographs of all groups prepared by experienced systematists and utilizing as many as possible of the national collections already in existence. No administrator should be left in any doubt that, at the present stage of our knowledge, comprehensive studies on the systematics and distribution of Antarctic organisms are of basic importance, not only to a narrow range of specialists, but to all biologists concerned with biogeography. The relatively few studies in depth of common Antarctic species have already shown the value of this approach in understanding adaptation to Antarctic environments and basic ecological relationships. The study of the biology of additional single important species and of the structure of some of the common assemblages will allow better understanding of the whole Antarctic benthic biota. Before the relationships of the Antarctic benthos are properly understood, much more work must be done in investigating the life on the shelves surrounding the Subantarctic Islands especially Marion and Prince Edward Islands, the Crozets, Kerguelen and Heard. XI. BIBLIOGRAPHY AND REFERENCES In compiling this bibliography, all papers concerned primarily with the systematics, distribution or biology of specific Antarctic benthic plants and animals have been included. Papers referring to the Subantarctic have, in general, not been included. Reference to reports of the Challenger Expedition and the German Deep-sea Expedition has been made only when the particular contribution has relevance t o Antarctic organisms in the restricted sense. Some short preliminary papers have been excluded when the main paper appeared within a short period, and where the preliminary paper was made completely redundant. When new taxa were proposed in these preliminary papers, these have usually been included. Adie, R. J. (1963). Geological evidence on possible Antarctic land connections. I n " Pacific Basin Biogeography " (J. L. Gressitt, ed.) pp. 455-463. Honolulu. Adie, R. J. (1970). Pas environments and climates of Antarctica. I n " Antarctic Ecology ". (M. Holgate, ed.) pp. 7-14. Academic Press, London and New York. Agateb, C. P. (1967). Some elasipodid holothurians of Antarctic and Subantarctic Seas. Antarct. Res. Ser. 2, 49-71. Allen, R. S. (1963). On the evidence of austral Tertiary and Recent brachiopods on Antarctic biogeography. I n " Pacific Basin Biogeography " (J.L. Gressitt, ed.) pp. 451-454. Honolulu. Allgen, C. A. (1933). Bipolaritiit in der Verbreitung freilebende mariner Nematoden. 2001. Anz., 105, 331-334.

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Allgen, C. A. (1959). Freeliving marine Nematodes. Further 2001. Reaulta Swed. Antarct. Exped. 1901-1903, 5 (2), 293 pp. Allgen, C. A. (1960). Antarktische meistens neue freilebende marine Nematoden aus dem Graham Lane. 2001.Anz., 164, 474-499. Andersson, K. A. (1905). Brutpflege bei Antedon hirsuta Carpenter. Wiaa. Ergebn. schwed. Siidpolarexped. 1901-1903, 5, 7 pp. Andriashev, A. P. (1958). Ichthyological research made by the Soviet Antarctic Expedition in 1955-1958, and some problems in antarctic zoogeography (in Russian). Inf. Biull. sw.antarkt. Eksped. 3, 63-66. (English transl. 1959, Int. Oceanogr. Congr. Washington, 129-130). Andriashev, A. P. (1962). On the systematic position of the giant Nototheniid fish from the McMurdo Sound, Antarctica. 2002. Zh. 41 (7), 1048-1050 (English summary). Andriashev, A. P. (1965). A general review of the antarctic fish fauna. Biogeography and ecology in Antarctica. Monographiae biol. 15, 491-550. Andriashev, A. P. and Permitin, Y. E. (1961). Ichthyological investigations. Rep. Soviet Antarct. Exped. 19, 261-273. Andriashev, A. P. and Tokarev, A. K. (1958). Ichthyofauna. Rep. Compl. Antarct. Exped. Akad. Sci. U.S.S.R., Descr. Exped. R.V. ‘’ Ob ” 1955-1956, 195-207.

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