Michele Day, age 7, of Bridgeport, Connecticut, for her question:

Why does a whale spout water?

The whale's spout looks for all the world like a fountain of water. But it really is a fountain of foamy moisture: It so happens that the seagoing giant cannot breathe underwater. He has lungs to breathe air, just as we do. This means that he can stay below only as long as he can hold his breath. Then he must come up to breathe out and fill his great lungs with another helping of fresh air.

The whale's big spongy lungs are warm and moist. This is where he holds each breath for half an hour or so. Naturally, the air down there gets moist and steamy. When he comes up to empty his lungs, this moist steamy air is puffed up like a fountain. Though from a distance it looks like a fountain of water, actually it is a plume of foamy moisture.