Discrimination of chemical signals from gastropods by hermit crabs

Some species of hermit crabs can locate chemically predation sites where snails are consumed and subsequently obtain their shells. This study addressed four questions: (1) Is chemotaxis to snail odors prevalent among hermit crabs? (2) Do members of hermit crab lineages respond similarly to common snail odors? (3) Do hermit crabs respond more acutely to snails whose shells they most frequently occupy? and (4) Does phylogeny of snails influence responses by hermit crabs? Two sets of congeners (Clibanarius vittatuslC. tricolor and Dardanus venosuslD. fucosus) in the family Diogenidae, and three congeners (Pagurus pollicaris, P. longicarpus, and P. annulipes) in the family Paguridae were tested. Fifteen species of snails from 11 families served as test odors. Hermit crab response was measured by the fondling display, where one hermit crab investigates the shell of a neighboring crab. The diogenids discriminated odors more readily than did the pagurids. Correlations between responses and shells most frequently occupied existed for C. vittatus and D. venosus. Clibanarius tricolor was the only crab to respond to confamilial test odors.