Name: Sea urchin
Scientific Name: Paracentrotus lividus (Lamarck)
Family: Echinidae
Group: Sea-stars, sea-urchins and sea-cucumbers
Class: Invertebrates
Size: 11-25 cm.
The sea urchin is an echinoderm, like the starfish and the sea cucumber. It feeds on other invertebrates and algae it scrapes from the rocks with its 5 teeth, located on the lower side of its body. These form a beak and are attached to a complex system of ossicles and muscles - Aristotle's Lantern. Its teeth are also used for digging shelters in the rocks! It has no eyes but its body is covered by light-sensitive cells. As soon as it detects light, it covers itself with shells, pebbles and algae. Though it does not seem likely, it moves with the help of spines and ambulacral feet. In spite of its hard limestone skeleton and spines, it is eaten by starfish, European crabs and some fish.
Photo by:
Sue Scott (www.marlin.ac.uk)
North Atlantic
