David Nolan, age 8, of Decatur, Ill., for his question:

HOW MUCH DOES A HIPPOPOTAMUS WEIGH?

Third largest animal that lives on land is the hippopotamus. Only the elephant and the rhinoceros are larger. There are two kinds: the river hippopotamus or common hippopotamus and the pygmy hippopotamus.

The river hippopotamus may weigh as much as 5,800 pounds, although most of the animals weigh between 2,500 and 3,000 pounds. The animal stands about five feet tall and ranges in length from 12 to 15 feet.

The pygmy hippopotamus has a smaller head in proportion to its body than does the river hippopotamus. It weighs from 400 to 600 pounds and stands only about 2 1/2 feet tall. It ranges from five to six feet long.

The river hippopotamus can be found in central and southern Africa where it lives in rivers, lakes and marshy ponds. The pygmy lives in Liberia, Sierra Leon and southern Nigeria.

A female hippopotamus has her first baby when she is five or six years old. In the wilds, hippopotamuses lives to be about 30 years old but in the more peaceful environment of zoos, they usually live to be 50 years old.