Because we have all seen trained seals in the circus, and because seals are such fun to watch in the zoo, they have a kind of fascination for us. Yet surprisingly little is known by most people about these creatures.

The order of seals includes the fur seals, the sea lions, hair seals, sea elephants, and the walrus. Seals are mammals, and they stand halfway between typical mammals such as cows and dogs, and such sea mammals as whales.

Actually, seals are descended from land mammals, which means that at one time they had to adapt themselves to living in the water. They have not lived in the water for as long as whales have. The result is that seals are not nearly so well adapted to aquatic life as whales are.

Seals cannot live under water all the time. Not only that, but their young must be born on land. In most cases, the babies must be taught to swim by their mothers! So you can see why a seal is halfway between a land mammal and a sea mammal.

As they adapted themselves for life in the water, certain changes took place. They developed webbed hind-limbs and paddlelike forelimbs to be able to swim fast. They acquired a layer of blubber to keep them warm. They have also either lost or reduced the size of their external, or outside, ears in order to lessen water resistance. And they began to feed on such sea-creatures as squid, octopuses, and fish.

Although nature has changed the seal greatly for water life, seals spend a good deal of time on land. They like to sun themselves or sleep on beaches or ice floes. On shore, they move either by wriggling along or by dragging themselves with their fore-flippers.

In the United States, the most familiar seals are the California sea lions. They are active and intelligent. They can be trained easily to do tricks, such as juggling and balancing balls on the ends of their noses.

The habits of seals make them an easy prey for man. This is especially so during their breeding season when they can be approached on the beaches or ice floes. For centuries, the Eskimos have used seals for food, clothing, and their oil for cooking and light.