OYARZUN, FX; University of Washington: Nurse eggs and cannibalism influence intracapsular development and survival in a poecilogonous spionid polychaete

Poecilogony is the ability to alternate between multiple developmental modes. Boccardia proboscidea, a spionid polychaete, has three different types of developmental strategies, including one in which capsules have approximately 90% nurse eggs and a mixture of planktotrophic and adelphophagic larvae. In this study I evaluated whether larval development was influenced by the conditions in which larvae develop inside the capsule, by manipulating combinations of larval types and nurse egg concentrations in vitro. Both larval types ate nurse eggs inside the capsule and when they were removed from capsules, showing an active feeding behavior from early stages. Both larval types grew more at higher concentrations of nurse eggs, but adelphophagic larvae grew faster. Planktotrophic larvae continued developing inside the capsule and ate nurse eggs, contrary to predictions from previous studies. I found no significant effect of larval combination on growth rate for either of the two developmental modes, however mortality of planktotrophic larvae was high due to cannibalism, implying that there are big disadvantages for planktotrophic larvae inside capsules that contain adelphophagic siblings. Mother�s capsule-opening behavior is hypothesized as a mechanism to regulate survival of different developmental types in nature.