Hazel Jenkins, age 16, of Camden, N.J. for her question:

JUST WHAT IS AN ECHINODERM?

Echinoderm is the general name of certain spiny skinned sea animals. Included in a large family of more than 5,000 different kinds of creatures are the starfish, brittle stars, sand dollars, sea cucumbers and sea urchins.

The echinoderm phylum, or large animal group, is the only major phylum made up entirely of sea animals.

Echinoderms have radial symmetry. This means that their body parts are arranged around the center of the animal like the spokes of a wheel around the hub. Echinoderm bodies are usually divided into fi ve sections around the center, with the mouth in the center of the underside.

Most echinoderms have many tiny tube like structures called tube feet that project from the body. They use the tube feet for feeding, sensing, breathing and moving.

Echinoderms reproduce by laying eggs which hatch into larvae and swim freely. Eventually the larvae sink to the ocean bottom and grow into adult echinoderms.