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.
Cancer pagurus, commonly known as the edible crab or brown crab, is a species of crab found in the North Sea, North Atlantic Ocean, and perhaps the Mediterranean Sea. It is a robust crab of a reddish-brown colour, having an oval carapace with a characteristic "pie crust" edge and black tips to the claws. A mature adult may have a carapace width up to 25 centimetres and weigh up to 3 kilograms. C. pagurus is a nocturnal predator, targeting a range of molluscs and crustaceans. It is the subject of the largest crab fishery in Western Europe, centred on the coasts of the British Isles, with more than 60,000 tonnes caught annually.
Pagurus bernhardus is the common marine hermit crab of Europe's Atlantic coasts. It is sometimes referred to as the common hermit crab or soldier crab. Its carapace reaches 3.5 centimetres (1.4 in) long, and is found in both rocky and sandy areas, from the Arctic waters of Iceland, Svalbard and Russia as far south as southern Portugal, but its range does not extend as far as the Mediterranean Sea. It can be found in pools on the upper shore and at the mean tide level down to a depth of approximately 140 metres (460 ft), with smaller specimens generally found in rock pools around the middle shore and lower shore regions, with larger individuals at depth. P. bernhardus is an omnivorous detritivore that opportunistically scavenges for carrion, and which can also filter feed when necessary.
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.
Pagurus longicarpus, the long-wristed hermit crab, is a common hermit crab found along the Atlantic and Gulf coasts of the United States and the Atlantic coast of Canada.
Pagurus novizealandiae, or the New Zealand hermit crab is a hermit crab of the family Paguridae, endemic to New Zealand. Its body is up to 16 millimetres (0.63 in) wide.
Pagurus hirsutiusculus is a species of hermit crab, commonly called the hairy hermit crab. It lives from the Bering Strait south to California and Japan, from the intertidal zone to a depth of 110 m (360 ft).
Dardanus pedunculatus, commonly referred to as the anemone hermit crab, is a species of hermit crab from the Indo-Pacific region. It lives at depths of up to 27 m and collects sea anemones to place on its shell for defence.
Pseudospongosorites is a genus of sea sponges belonging to the family Suberitidae. Currently, the genus is considered as monotypic, consisting of a single species Pseudospongosorites suberitoides. It is found in the Caribbean Sea, the Gulf of Mexico and on the Atlantic coast of the United States as far north as North Carolina. This species is known by the common name Florida hermit crab sponge, so named because hermit crabs often use it as shelter.
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
Pagurus prideaux is a species of hermit crab in the family Paguridae. It is found in shallow waters off the northwest coast of Europe and usually lives symbiotically with the sea anemone Adamsia palliata.
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.
Paguristes eremita, the eye spot hermit crab, is a species of hermit crab in the family Diogenidae. It is found in the Mediterranean Sea.
Pagurus forbesii is a species of hermit crab in the family Paguridae. It is found in the northeastern Atlantic Ocean and the Mediterranean Sea.
Labidochirus splendescens, commonly known as the splendid hermit crab, is a species of hermit crab found in the northeastern Pacific Ocean off the coast of North America. It is more heavily calcified and inhabits smaller mollusc shells than most hermit crabs.
Pagurus dalli, commonly known as the whiteknee hermit or whiteknee hermit crab, is a species of hermit crab in the family Paguridae. It is found in the northeastern Pacific Ocean at depths down to about 276 m (900 ft). It usually lives in a mutualistic symbiosis with a sponge, or sometimes a hydroid.
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.
