REPRODUCTION OF THE EXTERNALLY BROODING SEA ANEMONE EPIACTIS PROLIFERA VERRILL, 1869

¹ Department of Zoology, University of California, Berkeley, California, and University of California Bodega Marine Laboratory, Bodega Bay, California

1. Epiactis prolifera is a gynodioecious hermaphrodite, most of the intermediate-size individuals being female and most of the larger ones hermaphroditic. The population studied lacked purely male individuals.

2. Fertile animals may be found not brooding young, but all brooding individuals examined were fertile. Both females and hermaphrodites brood.

3. Gametogenesis proceeds in characteristic fashion, although oogenesis is accompanied by the formation of a trophonema between the oocyte and edge of the mesentery. All stages of both types of gametes were present throughout the year.

4. The zygotic nucleus divides a number of times and the resulting nuclei segregate into two layers before cytokinesis occurs. Mesenteries form while endodermal cells are still yolk-laden, and before it is all absorbed, tentacles with functional nematocysts and gland cells develop. Thus attached juveniles are capable of capturing prey.

5. Mucus and perhaps nematocysts, both of parental origin, are probably responsible for adhesion of the young to the parent's column. Enfolding by the parent ectoderm may also play a role in the early stages.

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