Amy Hamilton, age 12, of E1 Cajon, Calif., for her question:

WHY IS THE SLOTH SO SLOW?

Sloth is the common name of a family of South American animals which have slow and peculiar ways of moving about. They walk upside down, moving in the trees and hanging from the branches. They can hang so securely with their hooklike claws that they even sleep in this upside down position.

We use the word "slothful" to describe lazy people. The animal's sluggishness, scientists tell us, is caused by its very low body temperature. The sloth moves about one third of a mile per hour, when he moves at all. Many develop growths of green algae on their hair.

A sloth has almost no tail or ears. His hair is long and coarse and grayish in color. He seldom comes out of his tree and feeds on leaves, buds and young twigs.