The earth's oceans can reach depths of up to 11,000 metres.

That is deep enough to cover Mt. Qomolangma! The oceans

are incredibly (不能相信地) large and contain several different

habitats. To make it easier to describe the various parts of the

oceans, marine (海洋的)scientists usually divide the oceans into

five zones. Each zone is different mainly as a result of how much

sunlight reaches it.

Most of the life in the ocean can be found in the first zone, which

begins at the surface and goes down about 200 metres. Because there

is sunlight at this level, plants are able to grow.

　　 Marine animals such as dolphins, sharks, sea turtles and sea

lions, and of course a variety of fish, live in the sunlit (阳光照射的)

part of the ocean. It is difficult to hide from other animals in this area.

　　The second zone starts at 200 metres and goes down to about

1,000 metres. Some sunlight can reach this level, but it is not enoughfor

plants to grow. Because this zone is relatively dark, many of the creatures

that live here are able to make light with their body. The light from these

animals makes the water look like a sky with moving stars in it.

　　The third zone of the ocean is dark. This place, about 3,000 metres

deep, may not seem a likely habitat, but there are more creatures here

than one might think. Most of the animals that live here are black or

red because of the lack of light.

　　Below 4,000 metres, the temperature is near freezing and there is

no light at all. In fact, the zone is so dark and empty that scientists

named this zone after the Greek word for "no bottom". There is not

much life to be found in this cold and unpleasant part of the ocean, but

some small creatures still manage to survive here despite the high water

pressure.

　　The very deepest part of the ocean is found 2,000 metres further down. At this depth, the water pressure is extremely high and life is very difficult for the few creatures that live here. Compared to the other zones, this one has very little life. Since there is no light here, some of the animals do not have eyes.

Next time you look at the ocean from the beach or on a map, remember that what you are seeing is only the surface - only the beginning of the large and varied adventure.