The Decapoda or decapods are an order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 extant species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossils of the group date to the Devonian.
King crabs are decapod crustaceans in the family Lithodidae that are chiefly found in deep waters. King crabs are not true crabs and are generally thought to be derived from hermit crab ancestors within the Paguridae, which may explain the asymmetry still found in the adult forms. This ancestry is supported by several anatomical peculiarities which are present only in king crabs and hermit crabs. Although some doubt still exists about this hypothesis, king crabs are the most widely quoted example of carcinisation among the Decapoda. Several species of king crabs, especially in Alaskan and southern South American waters, are targeted by commercial fisheries and have been subject to overfishing.
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.
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.
Petrolisthes is a genus of marine porcelain crabs, containing these extant species:
The Paguridae are a family of hermit crabs of the order Decapoda. The king crabs, Lithodidae, are now widely understood to be derived from deep within the Paguridae, with some authors placing their ancestors within the genus Pagurus.
Pagurus is a genus of hermit crabs in the family Paguridae. Like other hermit crabs, their abdomen is not calcified and they use snail shells as protection. These marine decapod crustaceans are omnivorous, but mostly prey on small animals and scavenge carrion. Trigonocheirus and Pagurixus used to be considered subgenera of Pagurus, but the former is nowadays included in Orthopagurus, while the latter has been separated as a distinct genus.
Calcinus is a genus of hermit crabs in the family Diogenidae, containing the following species:
Paguristes is a genus of hermit crab in the family Diogenidae. It includes the following species :
Dardanus is a genus of hermit crabs belonging to the Diogenidae family.
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.
Ciliopagurus is a genus of hermit crabs, of the family Diogenidae, which are sometimes referred to as the "left-handed hermit crabs", because in contrast to most other hermit crabs, the left chela (claw) is enlarged instead of the right. They are found in the Indo-Pacific region and in the eastern Atlantic Ocean.
Ciliopagurus liui is a species of hermit crab native to the Gulf of Tonkin and waters to the south of Japan.
Ciliopagurus tricolor is a species of hermit crab native to Madagascar. It is one of four species in the "strigatus complex", having morphological similarities to C. strigatus, with the most prominent variance being coloration.
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.
Aniculus maximus, the hairy yellow hermit crab or large hairy hermit crab, is an aquatic hermit crab of the family Diogenidae.
Diogenes heteropsammicola is a species of hermit crab discovered during samplings between 2012 and 2016 in the shallow waters of the Japanese Amami Islands. This D. heteropsammicola is strongly associated with the walking corals. This hermit crab species is unique due to the discovery that they use living, growing coral as a shell. They live in the inside of the coral and can be distinguished from other types of hermits by their thin chelipeds and leg shape. Crustaceans of this type commonly replace their shell as the organism grows in size, but D. heteropsammicola are the first of their kind to use solitary corals as a shell form. Heteropsammia and Heterocyathus are the two solitary corals that this hermit species has been observed as occupying. These two coral species are also used as a home by symbiotic Sipuncula of the genus Aspidosiphon, which normally occupy the corals that were previously occupied by crabs.
Calcinus morgani, commonly known as Morgan's hermit crab, is a species of hermit crab in the family Diogenidae found in the Indo-West Pacific region, the type locality being Indonesia.
Pseudopaguristes is a genus of hermit crabs in the family Diogenidae.
Aniculus is a genus of aquatic hermit crab of the family Diogenidae.
