Sexual versus asexual reproduction in an oviparous rope-form sponge, Aplysina cauliformis (Porifera; Verongida)

The order Verongida, considered to be exclusively oviparous and dioecious, exhibits great range in body form, including thin-bodied, rope- and stick-form members which have been postulated to be morphologically adapted to exploit fragmentation as an important asexual reproductive process. Here we report results of a one-year survey of sexual reproductive stages in a rope-form verongid, Aplysina cauliformis, which test the hypotheses of verongiid sexual pattern and reduced resource allocation to sexual reproduction in rope-form sponges. Results confirm the verongiid pattern of oviparity, dioeciousness and production of small oocytes. Data also support the hypothesis that rope-form sponges are characterized by reduced investment in gamete production relative to sponges of other body forms. The sexual reproductive pattern of the main macrosymbiont (parasite) polychaete, Haplosyllis spongicola, shows no correlation to that of its sponge host.