Responses of deposit-feeding spionid polychaetes to dissolved chemical cues

Few studies have investigated capabilities or ecological implications of ch emical sensing in deposit feeders. We tested three species of spionid polyc haetes (Boccardia proboscidea Hartman, Polydora cornuta Bose, and Pseudopol ydora kempi japonica Imajima and Hartman) for responses to a variety of com pounds: amino acids, carbohydrates, organic acids, nucleotides, and plant a nd animal extracts that might have been used as general indicators of food quality or of the presence of specific foods. Five individuals of each spec ies were exposed to 44 different dissolved chemical cues introduced in slow , laminar flow to control location and dose (1 mM for most cues) of deliver y. Cues that altered feeding behaviors of one or more species were then tes ted against ten additional individuals of each species, in part to overcome dangers of multiple testing in the original screening. We observed differe nces among the three species both in their background behavioral patterns a nd in their responsiveness to dissolved cues applied ar palp level just abo ve the sediment-water interface, although significant changes in feeding be havior occurred only in Boccardia and Pseudopolydora. Taurine, threonine an d valine acted as strong phagodepressants, whereas proline was significantl y phagostimulatory to Boccardia. No hexoses elicited significant responses. Natural extracts were more stimulatory than the low-molecular-weight monom ers tested. (C) 1999 Elsevier Science B.V. All rights reserved.