Omar Salinas, age 7, of Houston, Texas, for his question:

How can a starfish see?

A starfish cannot see very well because his tiny little eyes are very poor. But he can see in five different directions. If he is a ten armed starfish he can see in ten directions, all at once. However, he could not see as far as the end of his nose  ¬if he had a nose, which he does not. What he sees is just a blurry mixture of light and shade. This does not bother him, because his eyes are just what he needs to find his way in his dim, watery world.

Every animal has his own special eyes. But human eyes.are some of the better ones in the world. Your bright eyes see clear outlines, near and far and in lovely colors. Nobody has invented colored movies as lovely as the pictures we see all the time  ¬with our own eyes. Dogs have fairly good eyes and cats can see in the dim darkness. But neither of them see colors. Most fishes have very good eyes that never close. But the little starfish is not a true fish.

Instead of real eyes, he has simple little dots called eyespots. He has a strange shaped body and his eyespots are not where you would expect to find them. His five arms are fixed like fingers to a flat round fist in the middle. This fist has a hollow tummy and a little round mouth on the under side. You would expect his eyespots to be somewhere near his mouth. But they are not.

If they were there, they would be no use at all, because the starfish tiptoes around with his mouth close to the wet sand, where he finds his food. He walks on his arms and they need to know where to go. So the starfish has an eyespot at the tapering end of each arm. It cannot see very far or very well. But it can tell him when the water is clear and bright and when a dark object lies in his path. And he has five of them to report the news from all around.

Each eyespot is a small bundle of sensitive cells that can tell the difference between light and darkness. It is fixed to a tiny tiny tentacle that can tell more than this. Experts think that it may be a sensitive little feeler. It may test the water for strong chemicals and sense whether it is warm or cool. When an eyespot's tentacle touches a hard, rough object, it may be able to tell whether it is a useless pebble. Or it may sense that it is a clam, with a delicious dinner hidden inside the rough, hard shells

This is all the starfish needs to know. You may not be able to open a stubborn clam, but he can. His arms have rows of little suckers and he uses them to pull pull pull the shells apart. Then he turns his hollow tummy inside out, through his mouth. He pokes it through the crack and digests the clam meat inside the shells. After dinner, his eyespots and their feelers help him to find his next delicious seafood snack.