[3] 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.

[5][6][7] 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.

[2] 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.

P. longicarpus faces extreme temperature and salinity fluctuations while inhabiting tidal pools due to the rising and falling tides, as well as changing climate.

[9] Long-wristed hermit crabs are scavenger feeders with a broad diet consisting of detritus, organic material found in ocean surface foam, microcrustaceans and algae.

[8][10] 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.

[12] One of the most important limited resources to hermit crabs is their shell, which is key to their survival and reproductive success.

From an energetic standpoint, if a shell is too large, crabs will extend unnecessary energy carrying and maneuvering it.

Larvae are later released into the surrounding ocean where they undergo several planktonic growth stages before developing into adult hermit crabs.