(full paper is archived in the Miller Library)
Title: The intertidal and subtidal distribution of four species of Pagurus (Fabricius) at Mussel Point, California
Student Author(s): Belknap, Robert
Location: Final Papers Biology 175H
Date: June 1965
Keywords: hermit crab
Abstract: A survey of the intertidal and subtidal areas off Mussel Point has shown: (1) the Pagurus spp. found intertidally occupy definite horizontal and vertical zones. The inner section of the transect contains primarily P. samuelis, the middle section P. granosimanus, and the outer regions P. hemphillii, with P. hirsutiusculus extending over most of the transect. (2) Juveniles of P. granosimanus are not clustered together in large quantities under rocks and algal cover, whereas the other three species of Pagurus exhibit high population densities under these conditions. (3) The data on population in figure 4 suggests the following hypothesis -- any sample with a population density greater than 100 per 0.1 meter squared will tend to be composed predominantly of one species. (4) Pagurus spp. may be located in terms of a preferred environment P. samuelis can be found in rocky exposed areas, where P. hirsutiusculus prefers regions with algal cover. P. granosimanus is found in the pools and mild surge channels of the middle and lower intertidal, where P. hemphillii prefers the deeper waters and constant surge of the lower intertidal and subtidal regions. (5) The number of Pagurus spp. is reduced in the subtidal region. P. hemphillii is the dominant species, P. granosimanus is found occasionally, with P. samuelis and P. hirsutiusculus absent entirely in the small region studied here.