Arlene Bomback, age 8, of St. Bonifice 6, Winnipeg, Canada, for her question:

Are there plants at the bottom of the ocean?

There are places where forests of trailing seaweeds cling to the floor of the ocean, waving their greenergy in the moving water. But wherever this happens, the water is sure to be shallow. Out in the deep ocean, there are masses of floating seaweeds. But wherever they are, they are sure to be near the surface. This is because seaweeds and all green plants need sunshine. They use sunlight to create their basic plant food.

The floor of the deep ocean is two or three miles below the surface waves. You would think that sunbeams could plunge down through the water, all the way to the bottom. After all they plunge hundreds of miles down through the air. But water is something different. Sunlight gets lost when it tries to plunge down through the deep sea.

Seaweeds and other plants can live only in the sunny surface water, perhaps to about half a mile deep. No plants can live on the deep ocean floor    where the water is blacker than blackest midnight.