RIORDAN, T.J.*; LINDSAY, S.M.: Chemically stimulated deposit-feeding in the spionid polychaete, Polydora quadrilobata

In marine soft-sediment habitats, chemical sensing by deposit feeding organisms most likely plays a critical role in feeding behavior, yet few specifics about this role and its ecological implications are known. As part of a multi-disciplinary investigation of chemoreception in the spionid polychaete Polydora quadrilobata, we have identified several phagostimulatory chemical cues. Using glass beads as a proxy for sediment, we tested for feeding responses to a selected number of potential cues that might be used to indicate food availability or quality. We presented two sets of beads to individual intact worms: one with and one without covalently bound compounds such as single amino acids, mixtures of amino acids, and single simple sugars. Worms were exposed to the beads under slow flowing seawater so that any dissolved cues were flushed from the test chamber. Each worm was videotaped for fifteen minutes immediately following the addition of beads and these records were scored for the time the worm spent in a variety of behaviors. Responses to beads with and without cues were compared to identify compounds as stimulatory, inhibitory, or inactive. Cues eliciting significant behavioral responses will be used in future neurobiological examinations of this species to identify and localize chemoreceptor cells. Supported by NSF grant OCE-9973327 to SML.