Lisa Taylor, age 10, of St. Catharines, Ontario, Canada, for her question:

Do all animals have hair?

There are at least a million different animals in the world    but only about 15,000 of them have real hair. That fuzzy stuff on the feelers of a moth does not count as real hair. Neither do the fluffy coats worn by certain caterpillars. Only the mammals have hair    and some of them are almost bald.

The mammals, as we all know, are the warm blooded, air breathing animals who feed their babies on mother's milk. No other animals nurse their babies and no other animals grow genuine hair. The furry cats are mammals, so are the dogs and horses and cows. Mammal hair may be coarse or fine and silky    and a sheep's hair is fleecy wool. The pig is an almost bald mammal. The great ocean going whale is a mammal and he too is almost bald.