Life under the sea

By Helen B.

The sea is a great body of water that covers 71% of the earths surface. People also call it the ocean. The people who study the sea are called Oceanographers.
The sea helps control the temperature by supplying the water for the rain. If there were no sea, life could not exist on this planet.

The sea is exploding with life. A true fish has a backbone, gills, and fins. Some animals are called invertebrates, some are mammels. Invertebrates are fish with no backbones. For example: a jellyfish, a starfish (Also called a sea star) and shellfish (scallops, crabs, snails, mussels).

Fish: How can fish breath under water? People have lungs that take oxygen from the air. Fish have gills that can take oxygen from the water. Water flows into the mouth, then the gills, and out through slits in the fish's sides.

Examples of fish are: tuna, pirahna, sharks.

What kinds of mammals are there? Whales, sealions, sea otters, and dolphins. They live in the water but must come to the surface to breathe.


Tide Pools are big puddles of water left on shore when the tide goes out. And here is what you might see in tidepools: starfish, periwinkles, sea anemones, and sea urchins.

A coral reef is made of tiny animals called coral polyps. Coral is colored by one-celled plants plants called algae. Thay live inside the coral polyps. Without algae coral would be plain white.

The ocean floor is mostly flat. An island is really a mountain formed under water. A valley is called a trench under water. The deepest trench is 7 miles down.

Arrow shows Marianas Trench.
Sources:
World Book 1991
The Oceans Martyn Bramwell, 1987
NatureScope 1988