Catherine Botto, age 10, of Portland, Maine, for her question:

Is it true that a whale is not a fish?

Nothing could be truer. Zoologists insist that a whale is not a fish. Neither are clams or oysters, shrimps or lobsters. Most animals that belong to the sea are cold blooded creatures. But only certain ones qualify as true fishes. They must have fishy fins and scaley skins, bony skeletons and gills for taking dissolved oxygen from the water. A whale is a warm blooded animal, which is why he needs all that fatty blubber to keep out the cold. His leathery skin has no scales and he has a peculiar tube for breathing air in and out of his enormous lungs. He cannot breathe under water like a fish.

Actually, the whale is classed as a mammal, because he was born as a live baby and fed on mother's milk. Cats, dogs and many other animals are mammals because their babies feed on mother's milk. All the different big whales and the smaller dolphins and porpoises belong to the same family. They lived on land, but ages ago they went to sea and now they belong there.