Population ecology of the Intertidal Anemone Actinia tenebrosa II Geographical distribution, synonymy, reproductive cycle and fecundity

Abstract

Synonymy and geographical distribution of A. tenebrosa are discussed. Reproductive cycle and fecundity were examined between 1972 and 1975 inclusive at Kaikoura, New Zealand. At any one time, up to 77% of the adult population developed gonads and 20-94% of adults were brooding young. The main periods of gonad development, November-April inclusive, coincided with the warmest annual sea temperatures. Over 99.4% of brooded embryos dissected from 1851 adults were tentaculate young; the rest were planulae. It is suggested that the normal reproductive mode of the observed population is cross-fertilizing labile gonochorism, in which adults change from one sex to the other within each breeding season. Brooding adults would therefore be the maternal parents of their brooded embryos, even though subsequently the brooders would appear to be asexual or could become functional males.