Henry Kay, age 10, of Tucson, Ariz., for his question:   

WHICH ANIMAL LIVES THE LONGEST?

An animal inherits his life span. If his grandparents and his great‑great‑great grandparents lived very long lives, then he can expect to do the same. He does not always get what he expects. After all, he may run into a fatal accident long before he reaches his normal life span.

There are at least a million different animals in the world and, barring accidents, each species can expect to live so long and no longer. They start out as youngsters, become mature parents, grow old and die. Elephants and other big animals tend to live a long time, but life span is not entirely related to size.

For example, an elephant can    expect to live about 60 years. The blue and red macaw, a parrot‑type bird, often lives to be 64. The long‑legged ostrich, biggest bird in the world, grows old and dies around the age of 50. An owl may live to be 24, and the splendid Canada goose may live to celebrate 32 birthdays.

A little mouse is an old‑timer at the age of 2 and rarely lives much longer‑‑unless he happens to be a pampered, tame mouse. Most of the fishes are eaten long before they grow old, especially the small ones. Barring accidents, a little seahorse may live six years, but a rainbow trout can expect only four years.

A goldfish can expect to live 25 years, and a big halibut may live 40 years. So far as we know, the fish that usually lives the longest is the sturgeon, who may reach 50. Perhaps the bird with the longest life span is the raven, a smart fellow who may reach 70.

A tiger may live 11 years, but a lucky lion may live to see 25. On the farm, the sheep may live 15 years, the goats 10 years and the horses 30 years. Even a wild zebra can expect to live 22 years.

Some frogs live six years and the bullfrog may live 15. But some of the reptiles live longer than amphibians or fishes, birds or mammals.  So far as we know the animals that live the longest are turtles. Some of the huge turtles of the Galapagos Islands have been known to live almost a century. But the ordinary little box turtle may reach the ripe old age of 123.

It is not an easy job to figure out the various life spans of the different animals. Some tend to live longer in captivity, where they are protected and well fed. Birds and other wild animals can be banded and checked, but this task is enormous. At present, the oldest old‑timer seems to be the box turtle. But maybe other animals can live even longer than 123 years.