Interspecific Shell Fighting in Three Sympatric Species of Hermit Crabs in Hawaii

Abstract

Interspecific competition is often difficult to measure due to the lack of a definitive limiting factor for the two (or more) species. The gastropod shell inhabited by a hermit crab represents a very discrete, definable portion of the ecological needs of every animal. A hermit crab must have protection for its soft abdomen or it will rather quickly be eaten. In addition, the ritualized shell fighting behavior patterns of hermit crabs (Hazlett, 1966a, 1966b, 1967) offer an easily observed specific behavioral parameter which reflects the extent of interspecific vs. intraspecific competition for this ecological factor.