Echinoids

Echinoids are invertebrate marine animals distinguished by a hard, spiny covering or skin hence the name from the Greek echinos spiny and derma skin. They have been used as food since ancient times particularly by the Romans. All echinoderms have a five way (pentamerous) symmetry and a water vascular system. They come in various forms and include the brittle-stars, sea urchins, starfish and sea cucumbers.

SEA URCHINS

STARFISH

BRITTLE-STARS

SEA CUCUMBERS

Sea urchins have a fragile circular shell. They move by using their spines.

Starfish are distinctive inhabitants of the shoreline, easily recognised by shape.

Brittle Stars are closely related to starfish, but are much commoner and smaller.

The sea cucumber has a tubular body with a mouth and anus at either end.