Burying Behavior in Relation to Substrate and Temperature in the Hermit Crab, Pagurus Longicarpus

Pagurus longicarpus (Say) migrates in autumn from a shallow estuary to deeper waters of Narragansett Bay, Rhode Island, when ambient water temperature are between 10° and 4° C. Critical thermal minimum experiments indicated that crabs ceased locomotor activity at approximately 3°C and righting response at 1.5°C. When presented with different substrates, crabs used their walking legs and, occasionally, their chelae to scoop a depression in the substrate. They were not able to construct a proper depression in gravel and, although they succeeded in burying themselves in both mud and sand, they remained only in sand. Winter dredging seaward of an estuary in which hermit crabs were found in fine sand. No crabs were found several meters away at 20 m on a silty mud bottom. The water temperature was less than 2°C in all areas sampled. It is hypothesized that, as environmental temperatures decrease, hermit crabs move into deeper water and bury themselves in regions of sandy bottom. Overwintering in this manner might decrease the predation of hermit crabs by benthic organisms while the crabs are in a state of torpor.