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Purple Sea Urchin

Page history last edited by Emanuel Brazil 10 years, 4 months ago


Scientific Name: Strongylocentrotus purpuratus



Purple sea urchins are echinoderms. The purple sea urchin has vivid purple spines that stick out from it's hard rounded body. The outer body has tentacle like things called tube feet which are used for movement, feeding and respiration. Sea urchins move by pushing with it's spines or using its tentacle like tube feet. These tube feet have suction disks at the end. These tube feet are used for respiration as well. They also use their tube feet to cover themselves in seaweed in an attempt to hide from predators such as crabs, fish and sea otters. 




The purple sea urchin inhabits rocky shores in shallow waters and tide pools, down to depths of 160 metres. It is found on the sea bed, typically occupying areas that experience strong wave actionThe purple sea urchin is found in the Pacific Ocean along the coast of North America, ranging from Alaska to Cedros Island, Mexico


Predator Adaptations:

The purple sea urchins diet consists of plants, animal matter, including Algae, dead fish, sponges, decaying matter, mussels, Barnacle's and kelp.


Prey Adaptations:

The purple sea urchin is prey of crabs, sunflower stars, snails, most birds, fish, sea otters, and humans. In some country the purple sea urchin is a delicacy. 


Symbiotic Interactions:

The purple sea urchin has a symbiotic relationship with small grooming organisms that live between their spines. At first they were thought to be feeding off of the food near the sea urchin or the particles of food attached to the sea urchin but this theory was proven wrong. These small organisms are a importance to the purple sea urchins care by keeping its surface free from other animal or plant organisms that may have been harmful. This type of symbiotic relationship is called Commensalism. 


Species Comparison:

Similarities: The purple sea urchin is similar to the sea star because they are both echinoderms. As for their habitat they both live among rocky surfaces and the sea floor. The sea stars arms have tube feet just like the sea urchin but way more. 

Differences: Sea stars are carnivores therefore they only eat meat but a sea urchins diet doesn't consist of only meat. 



Purple sea urchin. Arkive. May 27th 2013. http://www.arkive.org/purple-sea-urchin/strongylocentrotus-purpuratus/

Purple Sea Urchin. Cabrillo Marine Aquarium. May 27th 2013. http://www.cabrillomarineaquarium.org/exhibits/socal-species-details.asp?id=32

Purple sea urchin. Monterey Bay Aquarium. May 27th 2013. http://www.montereybayaquarium.org/animals/animaldetails.aspx?id=781774

Annie H. The Purple Sea Urchin. May 29th 2013. 


Stephanie Barccini. Arbacia punctulata. 2001. Animal Diversity Web, University Of Michigan Museum of Zoology. May 29th 2013. http://animaldiversity.ummz.umich.edu/site/accounts/information/Arbacia_punctulata.html















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