Warren Scott, age 9, of North Vancouver, British Columbia, Canada, for his question:

Do dolphins breathe under water?

Long ages ago, the dolphins lived on the land and breathed air. They are mammal animals and all the mammals must breathe air into their lungs to stay alive. These dolphin ancestors liked to fish for their food and spent more and more time swimming in the sea. In time their legs became more like fins and flippers, so they swam better and faster. At last they gave up coming back to the land and stayed in the sea all the time.

Nowadays the dolphins swim like fast fishes and play leap frog with the waves. They dive and swim under water    but they must come up for every breath of fresh air. They cannot breathe under water because their lungs must breathe air. Instead of a nose like yours, a dolphin has a blow hole in the top of his head. Every few minutes he comes up to blow the used air from his lungs and refill them with fresh air. When he goes below he closes his blow hole and holds his breath until he comes up for a refill.