Sea Urchin

Taxonomy
Phylum: Echinodermata
Class: Echinoidea
Order: Echinoida
Family: Strongylocentrotidae

Red and Green Sea Urchin

Distribution
Rocky areas throughout exposed and protected coastal waters.

Habitat
Rocky substrates, especially ledges and crevices; locate near or in giant or bull kelp beds and other brown algae in areas of moderate to swift currents; larvae drift and feed in plankton; juveniles settle near kelp beds, often associate with aggregations of adults, remain under adult spines until they reach 40 mm.

Tidal elevation
Extreme low tide to 100 m subtidal depth; most concentrated abundance just below the upper limit of range, usually 5-10 m subtidal.

Growth Rate

Red Sea Urchin: Slow, very dependent on food (i.e. kelp) supply; sexually mature at 50 mm test diameter reached at 2 yr; reaches commercial size, 100 mm at 4-5 yr; may reach 190-200 mm test diameter.

Green Sea Urchin: Slow; average size is 50-60 mm, but may reach a maximum size of about 85 mm.

 Source: Fisheries and Oceans Canada