Strongylocentrotus droebachiensis Green Sea Urchin These three S. droebachiensis were found on a dredge in Friday Harbor Photo taken by Heidee Leno. July 2002
Strongylocentrotus purpuratus (left) is much smaller than its relative Strongylocentrotus franciscanus (right), and has shorter spines. Photo by Dave Cowles, July 2005
This view shows the intricate network of plates and openings on the aboral side of the urchin. The periproct plates in particular are weakly held together and often collapse after the animal dies. The 5 gonopores are located in 5 genital plates arranged around the periproct. One of the genital plates is also the madreporite. Clicking the image will take you to a larger, unlabeled version. Photo by Dave Cowles, Oct 2012.
This species is often found within holes they grind in rock (probably over multiple generations) with their teeth and spines. They may even erode holes in steel pilings by flaking off rust. The photos above and below were taken at Little Corona del Mar, CA by Dave Cowles, March 2005
The species often covers itself with rocks and algae, which it holds onto with its tube feet, as seen in this tidepool at Dana Point, CA Photo by Dave Cowles, March 2005
