Behavioral Adaptations of Intertidal Hermit Grabs

SYNOPSIS. AS an ecotone, the littoral environment is often complexand is generally rich in numbers and species of organisms. Thedisadvantages of the biotope in terms of exposure to physicalfactors of both the marine and terrestrial environments arepatent, but the advantages are not so evident. The continualreplenishment of food brought from the sea, particularly fordetritus-feeding animals such as hermit crabs, coupled withthe possibility and ability to establish microhabitatswith microclimaticconditions may constitute the principal advantage. Escape fromspecialized predators may also be important. Hermit crabs havesuccessfully exploited most intertidal environments. As membersof the "benthic detritus-feeding guild" food is abundant, andby utilizing their shells in conjunction with movements withinthe littoral zone they have met successfully most of the rigorsof the environment. The shell also provides some protectionfrom predation, particularly from non-specialized predators.Indeed,the behavioral patterns associated with living in shells whichpermit the shell to serve as a microhabitat constitute the majoradaptation enabling the hermit crabs to exploit the intertidalenvironment so successfully.