Population Consequences of Shell Utilization by Hermit Crabs

Abstract

The nearshore hermit crabs Clibanarius vittatus, Pagurus pollicaris, and Pagurus longicarpus have broadly overlapping shell utilization patterns along the Texas coast. Effects of shell stress resulting from this overlap and from an overall shortage of shells on the reproductive potentials of the crabs were examined. Regression analyses indicate that shell weight and internal volume affect the clutch sizes of C. vittatus and P. pollicaris but not P. longicarpus. Clibanarius vittatus maintained in shells smaller than preferred grew more slowly than crabs maintained in shells of preferred size. Clutch size was highly correlated with crab size in this species. Several commensal animals, including polychaetes, gastropods, a hydroid, and a xanthid crab, consumed hermit crab eggs and/or zoeae in the laboratory. These egg predators were encountered in large shells occupied by ♂ ♂ more frequently than in shells in the size range utilized by ovigerous ♀ ♀. These results indicate that shell size may limit hermit crab clutch size through a variety of mechanisms.