Echinodermata
Sea urchins
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Although only four species of sea urchins are 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 Mesocentrotus franciscanus is harvested in several locations, mainly to provide gonads for use in the sushi industry (uni-zushi).

NOTE  formerly Strongylocentrotus franciscanus

   

ANIMATION of the snail's odyssey © Thomas Carefoot 2023
map used by the snail in A SNAIL'S ODYSSEY

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  • OR: play the animation to the left
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Sponge Sea anemone Abalone Tunicate

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

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

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

NOTE  recent molecular investigations suggest that the dominant west-coast sea-urchin species Strongylocentrotus franciscanus should be reclassified in the genus Mesocentrotus.  In view of this, any references in the ODYSSEY to this species from October 2014 will appear as Mesocentrotus franciscanus. Genus classification of S. purpuratus, S. droebachiensis, S. pallidus, and S. polyacanthus is unchanged. For a review of phylogenetic relationships in the Family Strongylocentrotidae, see Biermann et al. (2003)

Biermann et al.   2003   Evol & Dev 5: 360