Internal brooding of clonal propagules by a sea anemone, Anthopleura sp.

Abstract

We investigated the seasonal prevalence of reproductive activities and of the development of brooded propagules in an intertidal sea anemone, Anthopleura sp., on the rocky shore of Mutsu Bay, in northern Japan. A monthly examination of anemones, by dissection and histological techniques, revealed no sign of gonad development, but did reveal that they produce and internally brood propagules throughout the year. Release of propagules was observed in the field. This anemone population appears to be entirely asexual and agametic, and may persist solely through clonal propagation.

Distribution of intertidal sea anemones in Mutsu Bay, northern Japan

“…This dispersal pattern contrasts with the wider dispersal of the propagules of spawners, in which the buoyant planulae are dispersed by both tidal currents and wind (Harii et al 2002). Propagules of A. atodai are not buoyant and have no swimming phase (Isomura et al 2003). Therefore, it is unlikely that they float in the water column, and it also seems unlikely that they can disperse widely, like the propagules of blue coral.…”