GAMETOGENESIS AND REPRODUCTIVE PERIODICITY OF THE SUBTIDAL SEA ANEMONE URTICINA LOFOTENSIS (COELENTERATA: ACTINIARIA) IN CALIFORNIA

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Abstract
Sexual reproduction of the actiniid sea anemone Urticina (= Tealia) lofotensis was studied for one year (1976-1977) in 105 specimens collected by hand monthly at 7-16 m in Carmel Bay, California. Gametogenesis, evaluated by light microscopy, is typical for an actinian. Oocyte maturation is asynchronous, even within a mesentery, whereas spermiogenesis of each male is synchronous. Each oocyte is associated with a trophonema, and eggs may exceed 1200 µm in diameter. The study population is dioecious, with a significant excess of females. Gonad indices and histological data indicate that the period of maximum female ripeness ends in December as the male maximum begins. The spawning peak appears to occur then, just as water temperature begins to fall from its annual high. Some females contain large oocytes and seem to release eggs throughout the year. Greatest reproductive quiescence is in April and May, when water temperature is at its minimum.