Induced Settlement and Metamorphosis of Sand Dollar (Dendraster Ecentricus) Larvae in Predator‐Free sites: Adult Sand Dollar Beds

Dendraster excentricus larvae capable of metamorphosis presented with various substrates show a significant preference for adult—associated sand. Adult D. excentricus produce a chemical cue, possibly a small peptide (molecular mass <10 ,000), that is sequestered by some component in the sand and that is stable for at least 7 wk. Thus, larval settlement occurs within or adjacent to existing sand dollar beds which often contain several hundred adults per square metre. Experimental evidence indicates survival of newly metamorphosed D. excentricus is significantly reduced by an extremely abundant, tube—building predator. Leptochelia dubia (Crustacea: Tanaidacea). Tenaidacean and possibly other micropredators, however, are excluded from sand dollar beds by the reworking activities of adult sand dollars. Thus, preferential settlement of D. excentricus larvae near adults of the species should result in increased larval and juvenile survival.