Marine Life

Purple Sea Urchin
(Strongylocentrotus purpuratus)
Courtesy of Tom Haight

The two most common sea urchins in Southern California are the Purple Sea Urchin and the Red Sea Urchin. The Purple is the smaller of the two, growing to a diameter of approximately 3 inches, while the commercially harvested Red tops out at about 8 inches in diameter. Both are voracious eaters, dining on algae. Sea urchins seem to be better than their competitors in polluted water, which may account for their population boom in the last 50 years. Other factors would include the over harvesting of its predators, the sea otter and the sheephead. While not venomous, like some of it's tropical relatives, the spines can puncture the skin and break off, creating a nasty wound.