Sea Urchin

ID points

• Globe-shaped shell covered with long spines that can swivel
• Mouth in the centre of the underside, with five white teeth
• Slender tube feet reach out between the spines

Basics

Family

Echinoidea

Length

5–20 cm

Depth

0-50 m

Regions

Indo-Pacific reefs · Caribbean & W. Atlantic · Open ocean

Distribution

Coral and rocky reefs in all oceans

Diet

Algae

Easily confused with

Blue StarfishEntirely saturated cobalt blue, with no other markingsChristmas Tree WormTwo spiral cones of feathery gills, like a pair of tiny Christmas treesFeather Duster WormA ring of feathery gill plumes opens at the top like a duster

Fun fact

The Sea Urchin is an echinoderm that keeps coral reefs healthy by grazing seaweed and stopping algae from overrunning them. In some species the spines carry venom, and standing on one causes agonising pain.