Image of Strongylocentrotidae Gregory 1900

Description:

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.