Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting tail-like abdomen, 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 on each arm. They first appeared during the Jurassic period, around 200 million years ago.
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.
Johngarthia is a genus of crabs in the land crab family Gecarcinidae, formerly included in the genus Gecarcinus, and containing six species. The genus bears the name of John S. Garth, a 20th century naturalist who specialized in crabs and other arthropods.
Sesarma is a genus of terrestrial crabs endemic to the Americas.
Latreilliidae is a small family of crabs. They are relatively small, long-legged crabs found on soft bottoms at depths of up 700 metres (2,300 ft) in mostly tropical and subtemperate waters around the world. Their carapace is very small and doesn’t cover the bases of their legs, which protrude from the cephalothorax in a spider-like manner. The family and its type genus are named after Pierre André Latreille. The oldest known fossils from the Latreillidae have been dated to the middle of the Cretaceous period. It comprises seven extant species.
The Paw Paw Formation is a geological formation in Texas whose strata date back to the late Albian stage of the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
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.
Potamon fluviatile is a freshwater crab found in or near wooded streams, rivers and lakes in Southern Europe. It is an omnivore with broad ecological tolerances, and adults typically reach 50 mm (2 in) in size during their 10–12 year lifespan. They inhabit burrows and are aggressive, apparently outcompeting native crayfish.
Vultocinus anfractus is a species of crab, the only species in the family Vultocinidae. It has been found around the Philippines, Vanuatu and New Caledonia, and lives on driftwood. Its discovery forced a reappraisal of the relationships within the superfamily Goneplacoidea, and to the recognition of Mathildellidae, Conleyidae and Progeryonidae as separate families.
Heloecius cordiformis is a species of semiterrestrial crab found in mangrove swamps and mudflats along the east coast of Australia. Adults are around 25 mm (1 in) wide, with males being larger and having larger and more conspicuously coloured claws. The males wave their claws to communicate with other crabs, giving them their common name of semaphore crab. They can breathe both in air and under water, and feed at low tide on detritus in the sediment. H. cordiformis is the only species in the genus Heloecius and the family Heloeciidae.
Gelasimus vocans is a species of fiddler crab. It is found across the Indo-Pacific from the Red Sea, Zanzibar and Madagascar to Indonesia and the central Pacific Ocean. It lives in burrows up to 50 centimetres (20 in) deep. Several forms of G. vocans have been recognised, with their authors often granting them the taxonomic rank of full species or subspecies.
Guinotellus melvillensis is a species of crabs in the family Xanthidae, the only species in the genus Guinotellus. It is a benthic crab with an ovate carapace within the subfamily Euxanthinae.
Neoglyphea inopinata is a species of glypheoid lobster, a group thought long extinct before Neoglyphea was discovered. It is a lobster-like animal, up to around 15 centimetres (5.9 in) in length, although without claws. It is only known from 17 specimens, caught at two sites – one at the entrance to Manila Bay in the Philippines, and one in the Timor Sea, north of Australia. Due to the small number of specimens available, little is known about the species, but it appears to live up to five years, with a short larval phase. A second species, previously included in Neoglyphea, is now placed in a separate genus, Laurentaeglyphea.
Red Devil Vampire Crabs are decapod crustaceans part of Brachyura. They are land living, freshwater crabs from tropical areas and are endemic to Indonesia. Like all other crabs, they have a carapace, two chelae and ten jointed legs. They are omnivorous.
Geosesarma dennerle is a species of small land-living crabs found on Java, Indonesia.
Notopus is a genus of frog crabs from the family Raninidae, it consists of a single extant species and two extinct species.
Latreillia elegans is a species of crab belonging to the family Latreilliidae. This family of crabs is identified by their appearance as small, long-legged crabs. The species belongs to the genus Latreillia which has only five identified species: L. elegans, L. metanesa, L. williamsi, L.valida, and L. pennifera. It was previously thought that L. elegans and L. mannengi were two separate species, but it has since been revealed that the two species are synonymous. All the thought to be differences between L. elegans and L. mannengi were in actuality overlaps. The L. mannengi is simply referring to the close relative to the species of L. elegans found in the western Atlantic.
Leptuca thayeri, known generally as the Atlantic mangrove fiddler crab or mangrove fiddler, is a species of true crab in the family Ocypodidae. It is distributed all across the Western Atlantic.
Nanhaipotamon is a genus of freshwater crabs, in the subfamily Potamiscinae, found in southern China and Taiwan. As of 2018, 18 species have been described. The genus is named after the South China Sea, for it occurs mostly in coastal areas. The genus was first described by R. Bott in 1968 as Isolapotamon (Nanhaipotamon), i.e., a subgenus of Isolapotamon.
Limnopilos is a genus of small hymenosomatid crabs endemic to Southeast Asia. The genus was described by Christina Chuang and Peter Ng in 1991, who identified the new species Limnopilos naiyanetri and distinguished it from the closely related genus Hymenicoides. Its true taxonomic classification was debated for several years, but in 2007 the discovery of a new species of crab in this genus solidified the distinction between Limnopilos and Hymenicoides. Many aspects of the genus Limnopilos are still poorly understood. Their ecology and natural history have not been studied in detail, and their reproductive cycle remains mysterious.
