Meeting Abstract

31.10  Tuesday, Jan. 5  Differences in the timing of development of feeding structures and the acquisition of feeding ability between small-egg and large-egg larvae of Streblospio benedicti (Annelida, Spionidae) PERNET, B.*; MCHUGH, D.; California State University, Long Beach; Colgate University bpernet@csulb.edu

In marine invertebrates with planktonic larval development, evolutionary changes in per-offspring maternal investment are commonly associated with changes in larval nutritional mode. These coordinated shifts are thought to have occurred many times in many taxa. However, for most taxa we lack detailed understanding of the developmental changes that link changes in maternal investment to changes in larval nutritional mode. We are studying these developmental changes in larvae of the spionid polychaete Streblospio benedicti. Females of this species produce either small eggs that develop into planktotrophic larvae, or large eggs that develop into facultatively planktotrophic larvae. Feeding experiments show that larvae developing from large eggs acquire the ability to feed at a later stage (as indicated by segment number) relative to larvae developing from small eggs. We used comparative analyses of larval form to identify developmental correlates of this difference in the timing of acquisition of feeding ability. Specifically, we describe the timing of development of particle capture and digestive systems in both types of larvae, relating these developmental events to segment number as an indicator of developmental stage. Identification of morphological changes associated with differences in larval nutrition permits us to begin to apply the tools of developmental biology to explain linkages between maternal investment, larval morphology, and larval functional biology.