DISTINGUISHING FEATURES AND BEHAVIORS

Hermit crabs earned their name because they live in shells created by other mollusks and because of their tendancy to withdraw into their shells when they feel threatened. Two of the most common species of hermit crabs in Narragansett Bay are the broad-clawed and the long-clawed hermit crab. They can be distinguished fromeach other by the shape of their claws and their size.

Hermit crabs are not considered to be true crabs because their exoskeleton does not cover the entire body. To protect their soft abdomen, hermit crabs steal shells formed by other mollusks, usually snails, periwinkles, or whelks. Their bodies are curved and the last pair of appendages on the abdomen are modified to form a clamp, enabling the crab to maintain its position in the shell. It is very difficult to remove hermit crabs from their shells by pulling without injuring or killing them.

Long-clawed hermit crabs are the smallest species and inhabit vacant periwinkle and oyster drill shells. They live mostly in shallow water and are common in tide pools and salt marshes. The major claw is narrow and usually hairless. The broad-clawed hermit crab, the largest hermit crab in Narragansett Bay, has broad, flat major claws, and resides in large whelk shells or moon snails. They live in deeper waters of the Bay.

Hermit crabs are nomadic, always searching for new shells when they grow too big for their old ones. They move about actively, pausing only for the inspection of possible food or a new shell. Upon finding a new shell, they will get as close to it as possible and then quickly switch shells. Until if finds a new shell, a hermit crab will never leave the safety of the old shell. Larger crabs will often evict smaller crabs from a choice shell by using aggressive force.

As omnivorous scavengers, they eat small bits of fish, shore shrimp, dead plants, algae, and other hermit crabs.

RELATIONSHIP TO PEOPLE

Hermit crabs play an important role in the benthic community. They are scavengers, helping to recycle energy back into the ecosystem. The meat found in the tails of larger hermit crabs is often used as bait in recreational fishing.