Larvae of all seven species of echinoids occurring in coastal waters from southern British Columbia to central California have been reared through metamorphosis. Larvae of Dendraster excentricus, Brisaster latifrons, and Strongylocentrotus franciscanus can be distinguished from all others by skeletal traits alone. Living larvae of Strongylocentrotus droebachiensis and Strongylocentrotus purpuratus can be distinguished from all others by color of pigment spots combined with skeletal differences. Larvae of Allocentrotus fragilis and Strongylocentrotus pallidus have similar skeletons and pigment spots of the same color, so it is difficult to identify specimens even if they are alive. A key is provided for identification of echinoplutei.Development of Brisaster latifrons is similar to that of Brisaster fragilis in the Atlantic. The development is unusual for echinoderms in that large eggs develop into large feeding larvae with a long pelagic period. Moreover, the juveniles formed at metamorphosis have about the same diameter as juveniles of echinoids with much smaller eggs but similar pelagic periods.
Elevation of the intracellular pH activates respiration and motility of sperm of the sea urchin, Strongylocentrotus purpuratus.
