COLONY FORMATION VIA SEXUAL AND ASEXUAL REPRODUCTION IN SALMACINA-DYSTERI (HUXLEY) (POLYCHAETA, SERPULIDAE)

Reproduction and colony formation in the tubicolous serpulid polychaet e Salmacina dysteri (Huxley) were investigated on the Okinawan coral r eef. Numerous individuals of this species aggregate and construct an a rborescent pseudo-colony which is formed by physiologically unconnecte d individuals. This species reproduces both sexually and asexually. Th e proportion of the two modes of reproduction varied according to the position of individuals in the colony. Growing tips of colony branches included more asexually reproducing worms, while basal or central par ts of a colony contained more sexually mature ones. The predominant mo de of reproduction in a colony changed with colony size. In colonies w ith < about 500 worms, asexual reproduction was more frequent than sex ual reproduction, but in colonies with > 2,000 worms, sexual reproduct ion predominated.