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Thoracotremata
Thoracotremata is a clade of crabs, comprising those crabs in which the genital openings in both sexes are on the sternum, rather than on the legs. It comprises 17 families in four superfamilies . Evolution Thoracotremata is the sister group to Heterotremata within the clade Eubrachyura, having diverged during the Cretaceous period. Eubrachyura itself is a subset of the larger clade Brachyura, which consists of all "true crabs". A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: The internal relationships within Thoracotremata are less certain, with many of the superfamilies found to be invalid. The proposed cladogram below is from analysis by Tsang ''et al'', 2014: Superfamilies and families *Ocypodoidea ** Camptandriidae **Dotillidae ** Heloeciidae ** Macrophthalmidae **Mictyridae **Ocypodidae ** Ucididae ** Xenophthalmidae * Pinnotheroidea **Pinnotheridae * Cryptochiroidea ** Cryptochiridae *Grapsoidea **G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fresh w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eubrachyura
Eubrachyura is a group of decapod crustaceans (ranked as a "section") comprising the more derived crabs. It is divided into two subsections, based on the position of the genital openings in the two sexes. In the Heterotremata, the openings are on the legs in the males, but on the sternum in females, while in the Thoracotremata, the openings are on the sternum in both sexes. This contrasts with the situation in other decapods, in which the genital openings are always on the legs. Heterotremata is the larger of the two groups, containing the species-rich superfamilies Xanthoidea and Pilumnoidea and all the freshwater crabs ( Gecarcinucoidea, Potamoidea). The eubrachyura is well known for actively and constantly building its own burrows. The fossil record of the Eubrachyura extends back to the Cretaceous; the supposed Bathonian (Middle Jurassic) representative of the group, '' Hebertides jurassica'', ultimately turned out to be Cenozoic in age. Here is a cladogram showing Eubra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotremata
Heterotremata is a clade of crabs, comprising those crabs in which the genital openings are on the sternum in females, but on the legs in males. It comprises 68 families in 28 superfamilies. Evolution Heterotremata is the sister group to Thoracotremata within the clade Eubrachyura, having diverged during the Cretaceous period. Eubrachyura itself is a subset of the larger clade Brachyura, which consists of all "true crabs". A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: The internal relationships within Heterotremata are less certain, with many of the superfamilies found to be invalid. The proposed cladogram below is from analysis by Tsang ''et al'', 2014: Superfamilies * Aethroidea * Bellioidea * Bythograeoidea *Calappoidea *Cancroidea * Carpilioidea * Cheiragonoidea * Corystoidea * Dairoidea * Dorippoidea * Eriphioidea * Gecarcinucoidea * Goneplacoidea * Hexapodoidea * Leucosioidea *Majoidea * Orithyioidea * Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclodorippoida
Cyclodorippoida is a group of crabs, ranked as a section. It contains the single superfamily Cyclodorippoidea, which holds three families, Cyclodorippidae, Cymonomidae and Phyllotymolinidae. Below is a cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ... showing Cyclodorippoida's placement within Brachyura: References Crabs {{Crab-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromiacea
Dromiacea is a group of crabs, ranked as a section. It contains 240 extant and nearly 300 extinct species. Dromiacea is the most basal grouping of Brachyura crabs, diverging the earliest in the evolutionary history, around the Late Triassic or Early Jurassic. Below is a cladogram showing Dromiacea's placement within Brachyura: The larvae of Dromiacea resemble those of the Anomura more closely than those of other crabs. This may simply reflect their basal position in the crab phylogeny. The superfamily Eocarcinoidea, containing '' Eocarcinus'' and '' Platykotta'', was previously considered to be a member of the Dromiacea, but has since been transferred to the Anomura. The fossil record of Dromiacea reaches back at least as far as the Jurassic, and, if '' Imocaris'' is indeed a member, into the Carboniferous. Dromiacea primarily consists of two groups of superfamilies - Dromioidea and Homoloidea. See the below cladogram: Recent studies have found that some of the fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raninoida
Raninoida is a taxonomic section of the crabs, containing a single superfamily, Raninoidea. This group of crabs is unlike most, with the abdomen not being folded under the thorax. It comprises 46 extant species, and nearly 200 species known only from fossils. Below is a cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ... showing Raninoidea's placement within Brachyura: References Crabs Taxa named by Wilhem de Haan {{Crab-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gecarcinidae
The Gecarcinidae, the land crabs, are a family of true crabs that are adapted for terrestrial existence. Similar to all other crabs, land crabs possess a series of gills. In addition, the part of the carapace covering the gills is inflated and equipped with blood vessels. These organs extract oxygen from the air, analogous to the vertebrate lungs. Adult land crabs are terrestrial, but visit the sea periodically, where they breed and their larvae develop. Land crabs are tropical omnivores which sometimes cause considerable damage to crops. Most land crabs have one of their claws larger than the other. The family contains these genera: * ''Cardisoma'' * '' Discoplax'' * '' Epigrapsus'' * '' Gecarcinus'' * '' Gecarcoidea'' * '' Johngarthia'' * ''Tuerkayana'' See also *Sesarmidae, another family of terrestrial crabs *Coenobitidae The Coenobitidae are the family of terrestrial hermit crabs, widely known for their land-living habits as adults. They are found in coastal tropical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plagusiidae
The Plagusiidae are a family of crabs, formerly treated as a subfamily of the family Grapsidae, but have since been considered sufficiently distinct to be a family in their own right. The family Plagusiidae includes the subfamily Plagusiinae, comprising the genera ''Percnon'' and '' Plagusia'', which constitute a widespread group of litophilic, intertidal and subtidal crabs that are notorious for their speed and their agility. Six genera are included in the family: *''Davusia'' Guinot, 2007 *'' Euchirograpsus'' H. Milne-Edwards, 1853 *'' Guinusia'' Schubart & Cuesta, 2010 *'' Miersiograpsus'' Türkay, 1978 *''Percnon ''Percnon'' is a genus of crabs. It is "doubtfully placed" in the family Plagusiidae, and it has also been included in the family Grapsidae. Species Seven species are recognised: *''Percnon abbreviatum'' (Dana, 1851) *''Percnon affine'' (Henri ...'' Gistel, 1848 *'' Plagusia'' Latreille, 1804 References Grapsoidea Decapod families {{crab-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyptograpsidae
Glyptograpsidae is a family of crustaceans belonging to the order Decapoda The Decapoda or decapods (literally "ten-footed") are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, shrimp and prawns. Most decapods are scavengers. The order is esti .... Genera: * '' Glyptograpsus'' Smith, 1870 * '' Platychirograpsus'' de Man, 1896 References {{Taxonbar, from=Q2198320 Decapods Decapod families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocypodidae
The Ocypodidae are a family of semiterrestrial crabs that includes the ghost crabs and fiddler crabs. They are found on tropical and temperate shorelines around the world. Some genera previously included in the family are now treated as members of separate families in the superfamily Ocypodoidea, such as the Dotillidae and Macrophthalmidae. In 2016, the genus Uca was split into 13 genera by elevating its subgenera to genus rank, among other things. Further refinements have been made to the organization of the family, which has 4 subfamilies, about 13 extant genera, and about 180 described species as of 2020. The majority of the Ocypodidae species are fiddler crabs, the exceptions being the members of the genus ''Ocypode'', ghost crabs, and the genus ''Ucides'', mangrove crabs. Genera These genera belong to the family Ocypodidae: * '' Afruca'' Crane, 1975 * ''Austruca'' Bott, 1973 * '' Cranuca'' Beinlich & von Hagen, 2006 * '' Gelasimus'' Stimpson 1862 * ''Leptuca'' Bott, 1973 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sesarmidae
The Sesarmidae are a family of crabs, previously included in the Grapsidae by many authors. Several species, namely in '' Geosesarma'', ''Metopaulias'', and ''Sesarma'', are true terrestrial crabs. They do not need to return to the sea even for breeding. Genera The family contains these genera: *''Aratus'' *''Armases'' *'' Bresedium'' *'' Chiromantes'' *'' Clistocoeloma'' *'' Contusarma'' *'' Cristarma'' *'' Danarma'' *''Episesarma'' *'' Fasciarma'' *'' Geosesarma'' *'' Guinearma'' *''Haberma'' *''Karstarma'' *'' Labuanium'' *'' Leptarma'' *'' Manarma'' *'' Metagrapsus'' *''Metasesarma'' *''Metopaulias'' *'' Miersarma'' *'' Migmarma'' *'' Muradium'' *'' Namlacium'' *'' Nanosesarma'' *'' Neosarmatium'' *'' Neosesarma'' *'' Orisarma'' *'' Parasesarma'' *'' Perisesarma'' *'' Platychirarma'' *'' Pseudosesarma'' *'' Sarmatium'' *'' Scandarma'' *'' Selatium'' *''Sesarma'' *'' Sesarmoides'' *'' Sesarmops'' *'' Stelgistra'' *'' Tiomanum'' *'' Trape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mictyridae
''Mictyris'' is a genus of brightly coloured crabs, placed in its own taxonomical family, the Mictyridae. It inhabits the central Indo-West Pacific region. These crabs congregate on mud flats or beaches in groups of a few thousand, and filter sand or mud for microscopic organisms. They congregate during low tide, and bury themselves in the sand during high tide or whenever they are threatened. This is done in wet sand, and they dig in a corkscrew pattern, leaving many small round pellets of sand behind them. Species The genus contains eight species: The predictable behaviour of these crabs has led them to be used in experiments in a form of billiard ball computer A billiard-ball computer, a type of conservative logic circuit, is an idealized model of a reversible mechanical computer based on Newtonian dynamics, proposed in 1982 by Edward Fredkin and Tommaso Toffoli. Instead of using electronic signals li .... References External links * Ocypodoidea {{Crab-stub Cru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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