Delayed metamorphosis in Florida hermit crabs: Multiple cues and constraints (Crustacea: Decapoda: Paguridae and Diogenidae)

I examined the effects of food availability, shell availability and the presence of adults on survival and duration of the megalopal stage of the intertidal hermit crabs Pagurus maclaughlinae Garcia-Gomez, Paguristes tortugae Schmitt and Clibanarius vittatus (Bose) in the laboratory. I also considered the role of substrate availability on C. vittatus. All species delayed metamorphosis significantly in the absence of empty shells; shells also enhanced megalopal survival in P. maclaughlinae and C. vittatus. Water that had previously housed conspecific adults significantly improved megalopal survival and shortened time to metamorphosis in P maclaughlinae and P. tortugae. Shell-less megalopae of C. vittatus delayed metamorphosis when kept in adult-conditioned water, but metamorphosed more quickly in the presence of sediment. Food availability did not affect the duration of the megalopal stage in P. maclaughlinae or P. tortugae, whereas starved C. vittatus megalopae died in 8 d or less. Although food availability was associated with somewhat enhanced survival in P tortugae, the mechanism underlying this effect is unknown, since P. tortugae was not observed to feed as either megalopae or zoeae. As in other species of Pagurus, megalopae of P. maclaughlinae were not observed to feed, whereas zoeae and juveniles did feed. The differences and similarities in the nature and extent of the delay capabilities of P. maclaughlinae, P. tortugae and C. vittatus appear to reflect the interaction among various aspects of the ecology of the adults and energetic constraints on the megalopae.