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.
Belliidae is a family of crabs of the order Decapoda.
Discoplax is a genus of terrestrial crabs. It is very closely related to the genus Cardisoma.
Liocarcinus is a genus of crabs, which includes the flying crab, the vernal crab and several other swimming crabs.
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.
Gecarcinucoidea is a superfamily of freshwater crabs. Its members have been grouped into families in various ways, with some authors recognizing families such as "Deckeniidae", "Sundathelphusidae", and "Parathelphusidae", but now only the family Gecarcinucidae is currently recognized.
The Gecarcinucidae are a family of true freshwater crabs. The family Parathelphusidae is now demoted to the rank of subfamily, as the Parathelphusinae, within the Gecarcinucidae. "Family" Parathelphusidae is now considered as a junior synonym.
Lybia is a genus of small crabs in the family Xanthidae. Their common names include boxer crabs, boxing crabs and pom-pom crabs. They are notable for their mutualism with sea anemones, which they hold in their claws for defense. In return, the anemones get carried around which may enable them to capture more food particles with their tentacles. Boxer crabs use at least three species of anemones, including Bundeopsis spp. and Triactis producta. The bonding with the anemone is not needed for survival, however, and boxer crabs have frequently been known to live without them, sometimes substituting other organisms such as sponges and corals for the sea anemones.
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.
Eubrachyura is a group of decapod crustaceans 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 representative of the group, Hebertides jurassica, ultimately turned out to be Cenozoic in age.
Johora is a genus of freshwater crabs found in the Malay Peninsula and surrounding islands. It includes the following species:
Eriphioidea is a superfamily of crabs, containing the six families Dairoididae, Eriphiidae, Hypothalassiidae, Menippidae, Oziidae and Platyxanthidae. They are united by a number of characters, including a marked difference in size between the left and right claws, where the larger one has a crushing tooth, and the smaller one does not, and the relative breadth of the male abdomen.
Epialtidae is a family of crabs, containing the subfamilies:
Karstarma is a genus of karst-dwelling crabs formerly included in Sesarmoides.
Johngarthia weileri is a species of land crab in the genus Johngarthia from the eastern Atlantic Ocean.
Heikeopsis is a genus of crabs containing two species, Heikeopsis japonica and Heikeopsis arachnoides. The genus was originally described under the name "Heikea" by Lipke Holthuis and Raymond B. Manning in 1990, but was later revealed to be a junior homonym of the gastropod genus Heikea, erected by Orvar Isberg in 1934.
Conleyus defodio is a species of crab, the only species in the genus Conleyus and the family Conleyidae. It lives in rubble beds in Guam, and is named after the collector Harry T. Conley.
