Efficiency of aggregations for shell recruitment by hermit crabs.

Several species of hermit crabs form aggregations around gastropod predation sites. The literature suggests that these aggregations mainly function as “shell markets”, being mostly attended by hermit crabs occupying badly fitting shells. In the summer 2004, we conducted experiments and observations in a salt marsh of New England (USA) to understand the relative role played by aggregations in Pagurus longicarpus’ shell recruitment.