Competition for shelter between lobsters ( Homarus americanus) and Jonah crabs ( Cancer borealis): effects of relative size.
Date of Original Version
American lobsters and Jonah crabs inhabit rocky subtidal areas where they take shelter in crevices or burrows. Lobsters dominated crabs of equivalent size in competition for shelter. There was a broad overlap in size of lobsters and Jonah crabs cooccurring in Narragansett Bay, Rhode Island. In laboratory experiments, relative size did not affect the outcome of competition for shelter: lobsters were competitively superior to crabs of all sizes, but some crabs excluded lobsters from shelter. Fish predation on lobsters increased significantly when shelter was limited, but predation on crabs did not. Crabs could escape predation by rapid burrowing, while lobsters were dependent on locating preexisting refuges. Differential vulnerability to predation may explain the lack of size effect in competition between lobsters and crabs. The cost of not obtaining shelter is lower for crabs than for lobsters; thus, crabs utilize alternatives rather than compete with lobsters. -from Authors
Canadian Journal of Fisheries and Aquatic Sciences
Richards, R. A., and J. S. Cobb. "Competition for shelter between lobsters ( Homarus americanus) and Jonah crabs ( Cancer borealis): effects of relative size.." Canadian Journal of Fisheries and Aquatic Sciences 43, 11 (1986): 2250-2255. doi:10.1139/f86-276.