Reproductive seasonality in the comatulid crinoid Antedon bifida (Pennant) from the English Channel

Abstract

Genital pinnules from the north east Atlantic comatulid crinoid Antedon bifida (Pennant) were sampled monthly over a five-season period , from a site at Berry Head , English Channel, U .K . A. bifida uniquely broods its spawned ova and early larvae, during the period May to July . Nevertheless, a high level of sexual maturity was maintained throughout the annual cycle in both males and females. Three cellular gametogenic features: facets on the mature oocyte cell wall, nutritive phagocytes in the gonad lumen and yolk nuclei in the pre-vitellogenic oocytes, were present at all times of the seasonal cycle. Development of gonads along the length of an arm was not synchronous. All specimens sampled had pinnules, sections of arm or whole arms missing, an damean of 17% of all pinnules from the population were missing or regenerating The commonest small fish in the area, Crenilabrus was observed to nibble oil the genital pinnules. A strategy is suggested involving toleration of such losses, in place of less-expendable parts of the body.