The Decapoda or decapods are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns, and shrimp. Most decapods are scavengers. The order is estimated to contain nearly 15,000 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 fossil decapod is the Devonian Palaeopalaemon.
Xanthidae is a family of crabs known as gorilla crabs, mud crabs, pebble crabs or rubble crabs. Xanthid crabs are often brightly coloured and are highly poisonous, containing toxins which are not destroyed by cooking and for which no antidote is known. The toxins are similar to the tetrodotoxin and saxitoxin produced by puffer fish, and may be produced by bacteria in the genus Vibrio living in symbiosis with the crabs, mostly V. alginolyticus and V. parahaemolyticus.
Portunidae is a family of crabs which contains the swimming crabs.
Sand bubbler crabs are crabs of the genera Scopimera and Dotilla in the family Dotillidae. They are small crabs that live on sandy beaches in the tropical Indo-Pacific. They feed by filtering sand through their mouthparts, leaving behind balls of sand that are disintegrated by the incoming high tide.
Charybdis is a genus of swimming crabs in the family Portunidae; "Charybdis" is Greek for whirlpool.
Menippidae is a family of crabs of the order Decapoda.
Ovalipes australiensis is a species of crab found in southern Australia. Its range extends from Western Australia to Queensland, including Tasmania. It is fished commercially and recreationally, although it is not as important as the blue swimmer or mud crab.
Hexapus is a genus of crabs in the family Hexapodidae. It contains only three extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.
The Varunidae are a family of thoracotrematan crabs. The delimitation of this family, part of the taxonomically confusing Grapsoidea, is undergoing revision. For a long time, they were placed at the rank of subfamily in the Grapsidae, but they appear to be closest to Macropthalmus and the Mictyridae, which are usually placed in the Ocypodoidea. It may thus be better to merge the latter superfamily with the Grapsoidea, retaining the latter name as it is older.
Homolodromiidae is a family of crabs, the only family in the superfamily Homolodromioidea. In contrast to other crabs, including the closely related Homolidae, there is no strong linea homolica along which the exoskeleton breaks open during ecdysis. The family comprises two genera, Dicranodromia, which has 18 species, and Homolodromia, with five species.
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus Hexapus, and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of Stevea williamsi, from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa.
Romaleon is a genus of marine crabs formerly considered in the genus Cancer.
Pugettia is a genus of kelp crabs, in the family Epialtidae. It comprises the following species:
Zalasius is a genus of crabs in the family Xanthidae, containing the following species:
Atergatis is a genus of crabs in the family Xanthidae, containing the following species:
Brachynotus is a genus of crabs, comprising the following species:
Galenidae is a family of crabs, one of three in the superfamily Pilumnoidea. It contains four genera, three of which are monotypic. At present five species have been described in this family.
William Stephenson MBE (1916–1996) was a British/Australian marine biologist and academic.
Ovalipidae is a family of sand crabs in the order Decapoda. There are at least 3 genera and more than 20 described species in Ovalipidae. These were formerly members of the family Portunidae
