Belinda Sneed, age 10, of Santa Maria, Calif., for her question:

ARE CROCODILES MAMMALS?

A mammal must be a warmblooded animal, which means that his body has a sort of thermostat to keep him comfortable when things get too hot or too cold. The crocodile is a coldblooded animal, which means he gets his warmth from things around him. A mammal must wear fur, fleece or some kind of hair. Pigs and elephants have just a few bristles, but this is enough to qualify. A crocodile has a scaly skin and no hair of any sort.

These features are enough to disqualify the crocodile as a mammal. However, the real test comes with the children.

Mammals give birth to live babies and, most important, the babies are fed on mother's milk. The crocodile lays eggs and the babies have to fend for themselves. He is classed as a reptile, along with the snakes and the turtles.