Meeting Abstract
The intertidal zone of the United States Pacific Northwest carries many threats for hermit crabs, including predation, desiccation and temperature stresses. We conducted transect surveys examining the shell use of two species of hermit crabs (Pagurus granosimanus and Pagurus beringanus) in different microhabitats (exposed versus tide pools) at five sites on San Juan Island, Washington state. We found few empty shells available to hermit crabs, implying intense competition for refuges among individual crabs. Further, the two species inhabited different microhabitats. We compared the relative frequency of live gastropod species and the shells used by the hermit crabs, and examined whether shell weight varied consistently with hermit crab body mass across hermit crab species, shell species and sites. Our lab choice experiments revealed that hermit crabs do not prefer the gastropod shells they are most commonly found to inhabit in the field, and this choice was often not driven by shell weight alone. We demonstrated that while the preferred shells, which had thicker walls, could elevate protection against small predatory crabs, large predatory crabs could consume any of the shell choices.
