Gametogenesis and reproductive cycles in the sea anemone Anthopleura elegantissima (Brandt, 1835)

Reproduction in the sea anemone Anthopleura elegantissima was investigated in central California for 3 years. Gametogenesis of anemones from four sites is described, and annual reproductive cycles are compared at a harbor and protected outer coast site. Anthopleura elegantissima is dioecious, although one hermaphrodite was found. Spermatogonia arise in the endoderm of the mesenteries of males, migrate into the mesoglea, multiply, and differentiate into spermatozoa. In females, oogonia arise in the endoderm and migrate into the mesoglea where they undergo vitellogenesis. Spawning is synchronous within each population. Gamete growth is correlated with increasing temperature, and spawning occurs during periods of peak summer temperatures.