UNIQUE SHELL UTILIZATION BY REEF-FLAT HERMIT CRABS IN GUAM, MICRONESIA

Abstract

Calcinus latens is the hermit crab widely distributed in the Indo-Pacific region. Many authors have reported that C. latens uses gastropod shells having regular whorls and showing regular conical shape, however I found in a coral reef of Guam that many individuals of C. latens used shells of irregular whorls or peculiar shapes, such as the shells of Vermetidae, Cypraeidae, Conidae and they are highly damaged. These shells are significantly heavier than the shells of normal type and sometimes their center of gravity is various. It has been reported that heavier shells influence the growth rate and clutch size of hermit crabs and that unbalanced shells restrict the locomotion ability of hermit crabs. Thus this condition is regarded as worse for C. latens, and may result from the scarcity of normal shells in the reef.