Judy Ruff, age 12, of Highland Park, N.J., for her question:
DO SEA URCHINS LIVE IN THE ATLANTIC?
Lately we have been scared silly by nightmares of toothy sharks. Bathers along our sunny beaches half expect to be bitten by these ghastly jaws. However, nightmares of this sort are not likely to happen. So if you feel a toothy stab when wading in the water, do not panic. Chances are you have stepped on a prickly sea urchin.
There are 800 different sea urchins distributed throughout the seas around the world. Some types belong in the Pacific, others in the Indian Ocean and warm tropical seas near the equator. And many types of sea urchins prefer life in the Atlantic, from the cool waters north of New Jersey to the cool waters of South America.
Most live in shallow waters along the shores, often partly or completely buried in the sandy sea bed. Others are found farther out to sea, on ocean floors 1,500 feet below the surface. The smallest types are prickly balls no wider than half an inch. Most types measure 5 or 6 inches, though a giant sea urchin may measure 1 1/2 feet including his long prickly spine.
Living sea urchins look like pretty pincushions, tinted with yellow or red, green or orange, pink or purple. But great changes occur when the little sea dweller dies. The colored skin and outer layer of flesh soon wither and peel away. The spiky spines fall out of their sockets. only a bony round shell is left, ornamented with rows of pits and beady bumps. This is the sea urchin's skeleton ¬and if you find one washed up on the beach it becomes a collector's item for a seashell fan.
Many of these sea urchin remains are found on the beaches along almost all the Atlantic shores. Meantime their living relatives are submerged in shallow water. The sea urchins off the California coast often make pests of themselves. Some have been known to gnaw through steep pipes. Others devour the wondrous forests of kelp seaweed. However, the playful sea otters regard sea urchins as tasty snacks. As the sea otters multiply, there are fewer sea urchins, so the kelp beds grow thicker.