Long-wristed hermit crab

This species of hermit crab can reach a shell length of up to half an inch in size. P. longicarpus coloration can vary, but body color is most commonly gray, green or white. The right claw of P. longicarpus is much larger than the left, and each claw has a tan or gray stripe down the middle. The long-wristed hermit crab inhabits the empty shells of gastropods such as periwinkles, snails, and slugs for mobile shelter and protection of their soft abdomens. They anchor themselves into the shells by wrapping their abdomens around the columella, or axis, inside the vacant shell. Hermit crabs cannot produce their own shells, and therefore must scavenge for abandoned ones. Shell selection plays many crucial roles in P. longicarpus, such as providing protection from predators, desiccation and salinity stress, as well as influencing competition, population size, and reproductive behaviors in the species.