Although there are only 4 species of sea urchins found commonly on west-coast shores they represent a large and conspicuous component of low intertidal and subtidal communities. Because of their generally large sizes, abundance, and accessibility, and the important roles they play in community ecology as herbivores, they are well represented in research studies. The red urchin Strongylocentrotus franciscanus is harvested in several locations, mainly to provide gonads for use in the sushi industry (uni-zushi). 
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ANIMATION of snail meeting SEA URCHIN
© 2010 Thomas Carefoot

To learn about west-coast SEA URCHINS: select a topic from the sea-urchin menu at the top of the page

OR: play the ANIMATION of the snail meeting the SEA URCHIN

OR, if you want to see other animations: follow the snail on its ODYSSEY by CLICKING on any X-marked invertebrate on the map

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Phylum Echinodermata  (lit. “spiny skin” G.), including sea urchins, sea stars, sea lilies, brittle stars, and sea cucumbers

Class Echinoidea (lit. “like a spine” G.), including sea urchins and sand dollars

NOTE  the name “urchin” is derived from an old French/English word “urchone” (one of several spellings), used to describe a hedgehog or porcupine.  Since the invertebrate in question is also spiny, it became known as a “sea urchone” and, later, “sea urchin”.  Sea urchins and all other echinoderms are strictly marine. For a recent review of phylogenetic relationships in the Family Strongylocentrotidae, see Biermann et al. 2003 Evol & Dev 5: 360.
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