Oceans, Lakes, And Rivers

Studying Oceans, Lakes, and Rivers Earth has five oceans. They are the Indian, the Atlantic, the Arctic, the Pacific, and the Southern Oceans, Together, they cover more than 70 percent of Earth. About 97 percent of the world's water comes from oceans. Rivers and lakes can be found all over the world. Rivers are bodies of water that flow to lakes, oceans, and other rivers. Lakes are bodies of water surrounded by land.

• All Earth's life forms need water to survive. Healthy oceans are full of plants, fish, and other animals.

Ocean, Lake, and River Facts Did you know that the world's largest ocean is the Pacific Ocean? It covers about one-third of Earth. Read on to learn more about oceans, lakes, and rivers.

• Ocean water is salty. Most lakes and rivers have fresh water.This means there is very little or no salt in the water. • More than 99 percent of Earth's water is frozen or salt water.This means people cannot use it. • Eighty percent of life on Earth is found under the ocean's surface. • The longest river on Earth is the Nile River in Egypt. It is 4,160 miles (6,695 kilometers) long. • Nearly half of the world's lakes are located in Canada • Plants and animals cannot live in the Dead Sea because the water is too salty.

Salt Water Oceans are full of salt water. The salt in the ocean is not the same salt people put on food. The salt in ocean water comes from minerals. Minerals are found in soil and rocks. Water carries soil and rocks into rivers and lakes. The water in rivers and lakes flows into the oceans. Salt does not evaporate. The amount of salt in the ocean continues to build. About 3 to 3.5 percent of ocean water is salt.

• Ocean water contains about 4 ounces (118 mL) of salt per gallon (4 L) of water.

Fresh Water Fresh water has very little salt. Most lakes and rivers are fresh water. Still, some lakes have salt water.

About half the water a person uses each day comes from freshwater lakes and rivers. The rest of the water comes from groundwater. Fresh water weighs less than salt water because it has fewer minerals.lt is easier to float in salt water than fresh water.

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• LakeTahoe,on the border of California and Nevada, contains enough water for every American to use 50 gallons (129 L) per day for 5 years. j

Oceans From space, Earth appears mostly blue in color. Some scientists think Earth should have been named Oceanus. The world's oceans are really one big body of water known as the world ocean. The continents divide this body of water into the five oceans. The ocean floor has mountains, volcanoes, and valleys.

• Water can appear to be many different colors. The reflection of the sky, the depth of the water, and the amount of dirt in the water all affect color.

Rivers A river is a body of flowing water. Gravity causes rivers to flow from high to low ground. Rivers flow into lakes and other rivers and into oceans.

Most cities and towns are built near rivers. Rivers are used to water crops, ship goods, and to provide water for drinking. Rivers can also be used to make electricity.

Lakes Lakes form when water settles in a depression, or a low spot in the ground. Lakes can form anywhere in the world. Over time, they can disappear. When water in a lake evaporates, it disappears. Some lakes are called seas. Usually, this means the lake contains salt water. The largest lakes in the world are the Caspian Sea, between Europe and Asia, Lake Superior, partly in Ontario, Canada and partly in the state of Michigan, and Lake Victoria, in Africa.

• The Aral Sea is a large lake in the Middle East Farming has caused the lake to shrink 60 percent over the last 30 years.

Water Uses People use water to drink, wash, and clean. Only about 1 percent of the world's water can be used by people.

The Water Cycle Earth has a limited amount of water. Water recycles itself through the water cycle. Oceans, lakes, and rivers are part of the water cycle. This diagram shows how the water cycle work:

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Ocean Life Ocean creatures can be tiny like shrimp or large like whales. The world's largest mammal is the blue whale. It grows to between 80 and 110 feet (24 to 34 meters) in length and weighs up to 240,000 pounds (108,862 kilograms). Plankton are the smallest creatures in the ocean. They are very tiny floating plants and animals. Many fish and whales feed on plankton. Oceans are also home to many types of plants, including algae, kelp, and seaweed. These plants provide food and habitats for ocean life.

• More than one million species of plants and animals are known to live in the ocean.

Life in Rivers and Lakes Some types of fish or animals can only live In salt water or oceans. Others can only live in freshwater lakes and rivers. A few animals, such as the bull shark, can live in both salt water and fresh water.

Freshwater fish or animals can be very small or large.The smallest creatures in rivers and lakes include clams, snails, and worms. Larger animals include many fish species, such as salmon aqd rainbow trout.

Sockeye salmon are born in freshwater rivers and streams, but live most of their lives in the ocean, .i

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Working in Water An oceanographer is someone who studies the ocean. Oceanographers study the ocean floor, currents, water, and tides. Scientists can learn much from the oceans. They have discovered new medicines and foods by studying oceans. Studying water helps scientists predict long-term weather. Scientists can also learn how people and animals change water.

• Good oceanographers must be willing to spend about half their time conducting research in water.

Playing in Water Oceans, lakes, and rivers are popular places to spend holidays.There are many fun water activities, such as swimming, boating, and fishing. Americans take about two million trips to ocean, lake, and river beaches each year. More than half of the American population spend their vacation at a beach or lake. It is important to protect oceans, lakes, and rivers so that people can continue to enjoy them. Polluted oceans, lakes, and rivers are not nice places to visit.

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Waterskiing originated in the United States around 1900.

Protecting Water Oceans, lakes, and rivers are not only sources of à f water. They are habitats for life forms. Many types of plants and animals make their homes in water. Oceans, lakes, and rivers also hold resources such as oil, minerals, and food.

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The United States has many laws to protect oceans, lakes, and rivers. The laws protect the plants and animals that live in oceans, lakes, and rivers. They also set rules to keep the water safe to drink.

• In 1972, the U. S. Congress created clean water laws. As a result, water surfaces today are cleaner.

Life of Science Jacques Cousteau

Jacques Cousteau, a French naval officer, was well known for underwater exploration. He invented the self-contained underwater breathing apparatus, or S.C.U.B.A.This tank allows divers to breathe underwater. J .^^j^cques Cousteau was " also known for movies I he made while exploring • underwater.Two of his movies, The Silent World and World Without Sun, won Academy Awards. Cousteau also had his own television show ' called "The Undersea ; World of Jacques ^ Cousteau." On this "1«

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show, he talked about what he found during his underwater explorations.

Surfing Water Science How can I find more information about oceans, lakes, and rivers? • Libraries have many interesting books about oceans, lakes, and rivers. • Aquariums are great places to learn about oceans, lakes, and rivers. •The Internet offers some great Web sites dedicated to oceans, lakes, and rivers. Where can I find a good reference Web site to learn more about oceans, lakes, and rivers? Encarta Homepage www.encarta.com •Type any water-related term into the search engine. Some terms to try include "ocean" and "water pollution." How can I find out more about oceans, lakes, and rivers? United States Environmental Protection Agency Environmental Kids Club www.epa.gov/kids • Click on "water" to learn about water ecosystems and the different plants and animals that live in water.

Science in Action See the Difference This experiment will show the differences between salt water and fresh water.To complete the experiment, you will need: • 1 fresh egg • 1 large glass • water •salt • spoon Fill the glass with fresh water. Carefully add the egg to the glass of fresh water. Watch what happens. Remove the egg from the glass of fresh water. Next, stir some salt into the glass of water. Carefully replace the egg in the water. Watch what happens. Did the egg float better in salt water or fresh water? Why?

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What name do some scientists think Earth should have been given?

How much of the world's water can people use?

Do objects float better ¡n salt water or freshwater?

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What is the world's largest animal? What is a scientist who studies oceans called?

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continents: the seven large land masses on Earth—Africa, Antarctica, Asia, Australia, Europe, North America, and South America currents: paths along which a body of water moves evaporate: changing from a liquid or solid to a gas gravity: the force that pulls objects toward the center of Earth groundwater: water beneath Earth's surface

habitats: the natural places where plants and animals live minerals: natural substances that are not an animal or plant polluted: made dirty by harmful materials such as gases, chemicals, and waste recycles: returns to an original condition so a process can begin again tides: the regular rise and fall of water level in the oceans, caused by the pull of the Sun and Moon on Earth

animals 4,5,14,15,16, 18,20

lakes 4,5,6,7,10,11, 12,15,16,17,18,20

Cousteau, Jacques 19

oceans 4,5,6,8,9,11, 12,13,14,15,16, 17,18,20

fish 4,10,14,15 freshwater 5,7,15,21 glaciers 11,12

rivers 4,5,6,7,9,11, 12,13,15,16,17, 18,20 saltwater 5,6,7,15 water cycle 12-13

plants 4,5,14,18,20 pollution 17,20