Ken Van Tassell, age 10, of San Diego, California, for his question:

Why do frogs live in the water?

Baby frogs must live in the water because they cannot breathe air. They have fishy gills to take their oxygen from water. At this stage of their lives they are wriggly black tadpoles. Later, they lose their fishy tails and swap their fishy gills for a pair of air breathing lungs. They come up for air and leave the water to spend most of their time on land. However, they never go far from their favorite pond.

Frogs are called amphibians because they belong to both the land and the water. They have special soft skins that need a lot of moisture all the time. This is why they take frequent dips in the pond. Their special skins can take in oxygen from the water and a frog can sit on the bottom of his pond a long time before coming up for air. The water suits his way of life and he feels safely at home there. But a grown up frog, spends more than half his time squatting and hopping around on the ground.