John Potter, age 11, of Atlantic City, N.J., for his question:

HOW DID THE STICKLEBACK GET ITS NAME?

The stickleback is a name given to a family of small fishes of the Northern Hemisphere. They are called sticklebacks because some of their fins are made of strong, sharp separated spines.

Instead of having scales, the body of a stickleback is usually covered by hard plates.

There are both fresh water and ocean sticklebacks. The fresh water fish reach lengths of from one to three inches while the ocean sticklebacks grow to be about seven inches long.

The brook stickleback is common in the interior parts of Canada and in the states in the Great Lakes area. These fish, like other sticklebacks, build muff shaped nests of sticks and roots for receiving the spawn.

The male stickleback carefully guards the spawn. He also watches over the young for several days after the fish are hatched.

Sticklebacks eat the young of other fish.