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 do 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. Photo courtesy of Tom Haight.
When the urchin dies and its body is eaten or washes out of the shell, the spines fall off leaving a very delicate and beautiful shell for tide poolers and beach combers to admire.
