Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an asymmetric abdomen concealed by a snug-fitting shell. Hermit crabs' soft (non-calcified) abdominal exoskeleton means they must occupy shelter produced by other organisms or risk being defenseless.
The Coenobitidae are the family of terrestrial hermit crabs, widely known for their land-living habits as adults. They are found in coastal tropical regions around the world and require access to the ocean to breed.
The halloween hermit crab, also known as the striped hermit crab or orange-legged hermit crab, is a brightly colored aquatic hermit crab of the family Diogenidae. Besides its ability to routinely clean algae in aquaria, the halloween hermit crab's festive striped coloration also appeals to enthusiasts; it is considered the most brightly colored hermit crab in normal aquarium use.
Clibanarius is a genus of hermit crabs in the family Diogenidae. Like other hermit crabs, their abdomen is soft-shelled and sheltered in a gastropod shell. Typically marine like all their relatives, the genus includes C. fonticola, the only known hermit crab species that spends all its life in freshwater. The feeding rates of Clibanarius species change with temperature which, given their broad distributions, may have considerable consequences for the stability reef systems as sea temperatures rise in the future.
Coenobita perlatus is a species of terrestrial hermit crab. It is known as the strawberry hermit crab because of its reddish-orange colours. It is a widespread scavenger across the Indo-Pacific, and wild-caught specimens are traded to hobby aquarists.
The Diogenidae are a family of hermit crabs, sometimes known as "left-handed hermit crabs" because in contrast to most other hermit crabs, its left chela (claw) is enlarged instead of the right. It comprises 429 extant species, and a further 46 extinct species, making it the second-largest family of marine hermit crabs, after the Paguridae.
Paguristes cadenati, the red reef hermit crab or scarlet hermit crab, is a small species of hermit crab with a bright red body and yellow eyestalks that lives in the Caribbean Sea. The specific name honours the French ichthyologist Jean Cadenat (1908-1992), who collected the type specimen and sent it to the French carcinologist Jacques Forest, who described it as a new species.
Clibanarius erythropus is a species of hermit crab that lives in rockpools and sublittoral waters. It is found in the Mediterranean Sea, Black Sea and eastern Atlantic Ocean from the Azores to Brittany, the Channel Islands and as far north as the south Cornwall coast. Individuals may grow up to a carapace length of 15 millimetres (0.6 in).
The Pylochelidae are a family of hermit crabs. Its members are commonly called the 'symmetrical hermit crabs'. They live in all the world's oceans, except the Arctic and the Antarctic, at depths of 2,000 m (6,600 ft). Due to their cryptic nature and relative scarcity, only around 60 specimens had been collected before 1987, when a monograph was published detailing a further 400.
Dardanus megistos, the white-spotted hermit crab or spotted hermit crab, is a species of hermit crab belonging to the family Diogenidae.
Clibanarius fonticola is a species of hermit crab from Vanuatu. It lives exclusively in fresh water, the only hermit crab in the world to do so. While a number of other hermit crabs are terrestrial or live in estuarine habitats, and certain brackish water species can tolerate low salinity levels for a time, no other hermit crab spends its entire life in fresh water; the only other fully freshwater anomurans are the South American aeglids.
The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, Clibanarius fonticola, on Espiritu Santo, Vanuatu. They live between 20° S and 50° S, at altitudes between 320 and 3,500 m (1,050–11,480 ft).
Ciliopagurus liui is a species of hermit crab native to the Gulf of Tonkin and waters to the south of Japan.
Pagurus samuelis, the blueband hermit crab, is a species of hermit crab from the west coast of North America, and the most common hermit crab in California. It is a small species, with distinctive blue bands on its legs. It prefers to live in the shell of the black turban snail, and is a nocturnal scavenger of algae and carrion.
Porcellana sayana is a species of porcelain crab that lives in the western Atlantic Ocean, often as a commensal of hermit crabs. It is red with white spots, and has a characteristic bulge behind each claw.
Dardanus venosus, the starry-eyed crab or stareye crab, is a species of hermit crab in the family Diogenidae. It occurs in shallow water on the eastern coasts of America from Florida southward to Brazil. It is sometimes kept in reef aquaria.
The thinstripe hermit crab, Clibanarius vittatus, is a species of hermit crab in the family Diogenidae. It is found in the Caribbean Sea, the Gulf of Mexico and the western Atlantic Ocean.
Cancellus is a genus of hermit crabs in the family Diogenidae. Members of this genus are most commonly found living in small crevices in the outer continental shelf at mesophotic depths. They can be found living in rocks, sponges, and algae among other places. The genus has a cosmopolitan distribution. Four species are known from the western Atlantic.
Janaria is a genus of commensal athecate hydroids in the family Hydractiniidae. It is a monotypic genus and the only species is Janaria mirabilis, commonly known as staghorn hydrocoral. It is a colonial species and lives on a shell occupied by a hermit crab. It is native to the tropical and semitropical eastern Pacific Ocean.
Paguristes puncticeps is a hermit crab, in the family Diogenidae. It is found in shallow waters in the tropical western Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico. Like other hermit crabs, it lives inside an empty mollusc shell, which it changes periodically as it grows.
