Annette Johnson, age 9, of Charlotte, N.C., for her question:

WHAT ARE AMPHIBIANS?

Millions of years ago, the scientists tell us, occasional fishlike creatures breathed air with great difficulty and became the first eventually to walk on the

land. As the ages passed, descendants breathed air more easily and traveled farther from water in which they had passed their infancy. XX

A class of animals is now living that we call amphibians. They are bound to water by a need for keeping their eggs moist and for the nurture of their larval stage, but as soon as they reach adulthood they can hop or crawl away from the water to a new home on dry land.

Amphibia means double life and refers to the ability of the animals to live in water or on land at different times. During the water phase, gills like those of fish help them absorb oxygen from the water. Some amphibians retain their gills for life and never leave water permanently, but in most the gills are absorbed at the same time lungs begin to function.

We have three orders of amphibians living today: the Salientia, which includes frogs and toads and is the largest group; the Caudata, which includes the salamanders, and the Gymnophiona, legless, burrowing caecilians that live only in the tropics and are not seen often because of their secret habits.

Most caecilians burrow in soft earth and seldom come above ground except when a rainstorm fills their burrows. They are limbless and are extremely primitive in structure. They do not have pelvic girdles.

Salamanders are also secretive and like to hide. There are 225 different species and subspecies known at the present time, so they're not what you would call rare.

Largest group of amphibians are in the frog and toad family. Some 2,600 different species make up this very large family. They live just about any place on earth with the only exceptions being snow capped mountaintops, waterless deserts and some of the islands in the Pacific Ocean.

Members of the toad and frog family are born in the water and spend the first phase of their lives under the wet stuff. Then as life advances for them, they come up for air and eventually become creatures of the land.

Amphibians do not make good pets since they do not do well in a restricted area. It is best to enjoy them as they run free.