When a hermit crab spots a new shell, it’ll size up the shell for a good fit. If the shell is too big, the prospecting hermit crab will sit back and wait to steal the castoff shell of a larger crab ...

Size does matter, at least when it comes to some hermit crabs, who appear to have evolved longer penises so they can stay in their shells to protect their homes during sex.

The supply and quality of empty gastropod shells may play important roles in the ecology and evolution of hermit crabs. We compare the life histories of three subtidal hermit crabs in Nantucket Harbor ...