Experimental evidence of polymorphysm of sexual development in Capitella sp. B (Polychaeta: Capitellidae) from Barcelona, Spain

Abstract

The development and growth of Capitella sp. B obtained from Barcelona were studied under culture conditions. Trochophore and metatrochophore larvae hatched non-simultaneously (two release periods) from single brood tubes. This is the first laboratory evidence of polymorphysm of sexual development in the Capitella capitata species-complex. During the first release period, only free swimming trochophores hatched. The females, still bearing larvae inside the brood tube, were transferred to another dish. After three days, ciliated metatrochophores hatched from 8.7% of the transferred broods. In a culture experiment, larvae maintained in sediment enriched with artificial food grew to immature and mature adults. In this condition, the larvae that hatched during the first release reached the immature adult stage, while the larvae derived from the second release became mature adults. Oogenesis was observed three times in one female from the second release, though no spawning and fertilization occurred under incubation with sib mature males. Two different sizes of coelomic oocytes were observed. Polymorphysm of sexual development is discussed as an advantageous reproductive strategy enhancing survival in organic enriched sediments.