Long-wristed Hermit Crab

Appearance

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.

Distribution

"P. longicarpus" is commonly found along the Atlantic coast of Canada and the United States, from Nova Scotia to Northeastern Florida, as well as along the Gulf coast of the United States to Texas.

These hermit crabs can be found in intertidal and subtidal Atlantic environments on a variety of substrates and at depths of up to 200 meters.

Behavior

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.

Reproduction

"P. longicarpus" breeding season occurs from late March until October with the peak breeding in April.

The main period of reproduction in the species occurs during the spring. Male hermit crabs will compete with other males for available females during breeding season. "P. longicarpus", like many crustaceans, performs precopulatory mate-guarding behaviors, where males will grasp ahold of the female’s shell once the female releases a pheromone signaling sexual maturity.

Male and female crabs can be differentiated based on their pleopod morphology. Males have two pleopods, while females have three branching pleopods where her eggs are attached. "P. longicarpus" have sexual internal fertilization and must exit their shells in order to mate. After fertilization, the female houses the eggs inside her shell where they grow and develop. Larvae are later released into the surrounding ocean where they undergo several planktonic growth stages before developing into adult hermit crabs.

Food

Long-wristed hermit crabs are scavenger feeders with a broad diet consisting of detritus, organic material found in ocean surface foam, microcrustaceans and algae. Feeding is performed by scooping sand or other substrate with the chelipeds, ripping and tearing food, and then passing it to the mouth for consumption.

Predators

The major predators of "P. longicarpus" include birds, fish, snails, octopuses and other crabs, including the green crab. Hermit crab shells are crucial for protection and minimizing predation, and therefore proper shell selection is vital. "P. longicarpus" will avoid selecting shells with extensive damage because they are more vulnerable to predation. The most common type of damage to hermit crab shells is the presence of small holes. These holes are caused by the drilling of nacticid gastropods in order to prey on the original gastropod hosts of the shell.