OCEAN
Oceans and seas cover nearly three-quarters of the earth's surface and contain most of its water. Billions of years ago, life on Earth began in the oceans. Today, they contain thousands of different sea creatures, from tiny floating plankton to huges whales.
The ocean's salty water is always water is always moving. It is stirred up by the earth's spinning movements and by winds blowing over it. These movements make huge circular currents that carry water to warm parts of the world and warm water to cold parts. The wind blows the surface of the ocean into waves. these waves can travel thousands of miles before they die out of reach land. As they get near the land, waves grow taller and thinner. Then they topple over and break on the shore.
Ocean Life: Plankton
Wherever there are enough nutrients, tiny plants grows in the ocean and drift with the current. Small animals eat the plants, and drift with them. Together, these plants and animals are known as plankton. Sea birds, bigger fish, and seals feed on the plankton-eaters. Without plankton there would be no life in the ocean.
Coral Reefs
Multi-colored coral reefs are made by tiny animals called polyps (POL-ips) that leave their shells behind when they die. When new polyps grow on the old shells, the reef becomes larger.
