A fiddler crab, sometimes known as a calling crab, may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae. A smaller number of ghost crab and mangrove crab species are also found in the family Ocypodidae. This entire group is composed of small crabs, the largest being slightly over two inches (5 cm) across. Fiddler crabs are found along sea beaches and brackish intertidal mud flats, lagoons and swamps. Fiddler crabs are most well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, while the females' claws are both the same size.
Mary Jane Rathbun was an American zoologist who specialized in crustaceans. She worked at the Smithsonian Institution from 1884 until her death. She described more than a thousand new species and subspecies and many higher taxa.
Pinnotheres is a genus of crabs, including the pea crab. Many species formerly in Pinnotheres have been placed in new genera, such as Zaops ostreus, the oyster crab and Nepinnotheres novaezelandiae, the New Zealand pea crab. The species currently recognised in the genus Pinnotheres are:
Parathelphusinae is a subfamily of freshwater crabs, which was formerly placed in the family Parathelphusidae; they are mainly found in South and Southeast Asia, but also found elsewhere in Asia and in Australia. The family is now considered as a junior synonym of the family Gecarcinucidae.
Potamonautes is a genus of African freshwater crabs in the family Potamonautidae. It is both the most widespread and most diverse genus of African freshwater crabs, including more than half the species of this continent. They are found in most freshwater habitats of the African mainland and some species are semi-terrestrial.
Potamonautidae is a family of freshwater crabs endemic to Africa, including the islands of Madagascar, the Seychelles, Zanzibar, Mafia, Pemba, Bioko, São Tomé, Príncipe and Sherbro Island. It comprises 18 extant genera and 138 extant species. Fossil remains dating from the Late Miocene period have been attributed to the family Potamonautidae.
Geosesarma is genus of small freshwater or terrestrial crabs, typically less than 10 mm (0.4 in) across the carapace. They live and reproduce on land with the larval stages inside the egg. They are found from India, through Southeast Asia, to the Solomon Islands and Hawaii.
Sesarma is a genus of terrestrial crabs endemic to the Americas.
Atergatopsis is a genus of crabs in the family Xanthidae, containing the following species:
Around 1,300 species of freshwater crabs are distributed throughout the tropics and subtropics, divided among eight families. They show direct development and maternal care of a small number of offspring, in contrast to marine crabs, which release thousands of planktonic larvae. This limits the dispersal abilities of freshwater crabs, so they tend to be endemic to small areas. As a result, a large proportion are threatened with extinction.
Seychellum alluaudi is a species of freshwater crab endemic to the Seychelles, and the only true freshwater crab in that country. It lives in rainforest streams on the archipelago's granitic high islands. Although it may be abundant, little is known about its biology. If its habitat were to decline in quality, S. alluaudi might become endangered, but it is currently listed as Vulnerable on the IUCN Red List.
Demanietta is a genus of freshwater crabs found in Indochinese Peninsula of Southeast Asia. Most of them are found in fast flowing water habitats, giving their common name "waterfall crabs". The genus contains ten described species:
Syntripsa flavichela is a species of freshwater crab found in Lake Towuti and Lake Mahalona on the Indonesian island of Sulawesi.
Oziotelphusa ceylonensis is a species of freshwater crabs in the family Parathelphusidae. It is endemic to Sri Lanka. The species is not threatened in their habitats, where they observed to be survive well in man-made settlements as well. The species was discovered from nine localities around Kandy hills. The preferred habitats are embankments of paddy fields, where many irrigation canals constructed to provide continuous supply of water to the field.
Eosamon is a genus of freshwater crabs in the subfamily Potamiscinae, found in East and South-East Asia.
Sayamia is a genus of freshwater crabs, found in South-East Asia. Three species are included on the list of least concern (lc) arthropods, but S. melanodactylus is endangered.
Mekhongthelphusa is a genus of freshwater crabs in the family Gecarcinucidae, found in South-East Asia.
Guinothusa is a genus of freshwater crabs, found in South-East Asia.
Esanthelphusa is a genus of freshwater crabs, found in South-East Asia.
Leptuca is a genus of fiddler crabs belonging to the family Ocypodidae.
