Preliminary comparisons of Pagurus samuelis (Decapoda: Anomura) populations from north and south Monterey Bay, California

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An ecological study on the population dynamics of the hermit crab Pagurus samuelis was carried out in two locations of Monterey Bay, California during July, 2003. Morphometries, including shield length, wet weight, sex, shell species and shell weight, were collected on all hermit crabs and compared between sites. In addition, empty gastropod shells and individuals of each snail species were counted at each site to give a profile of relative abundances for those shells available to hermit crab populations.

Results of the study demonstrate that although the ranges of hermit crab sizes and body wet weights were approximately equal over both sites, there was a significant difference in the mean size of hermit crabs between sites. While at Santa Cruz, males constituted the largest crabs but did not outnumber the females, at Carmel males were both the largest crabs found and more numerous than all females combined.

The range of shell species used by P. samuelis was more than the range of snail species collected, suggesting that shells are being brought into local populations of hermit crabs by either inshore wave action or immigrant individuals.

This study constitutes a preliminary investigation in a series of studies that are to be carried out over the course of an entire year.

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