Cabrillo Marine Aquarium

Purple Sea Urchin

Strongylocentrotus purpuratus


Fun Facts

    Sea urchins have tube feet, which they use for attachment, locomotion and feeding.

    Sea urchins are one of the favorite foods of sea otters, wolf eels, and California sheephead.



  The purple sea urchin is a spiny, hard-shelled organism that lives along the rocky shore. It lives from the intertidal zone down to depths of about 33 feet. When in high numbers, sea urchins can graze away all seaweeds except the hard-textured coralline algae. To survive the pounding surf in the intertidal, the purple sea urchin often lives in shallow depressions in rocks. These “foxholes” are dug by the urchins as they hold on with their suction cup tube feet and scrape the rock with their teeth and spines. They have tiny jaw-like pedicellariae among the spines that keep the body surface free of settling organisms and may also deter predators.
Rocky shore organisms are at risk from coastal development and pollution, including waste oil and agricultural runoff. Some areas are also in danger of being "loved to death" by visitors. Tread lightly as you explore the rocky intertidal to avoid crushing algae and animals, and never take organisms from their habitat.
Purple sea urchins are usually found at the Aquarium in tanks number 1, 3, 6 and the Tidepool Touch Tank.