Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. Many other animals with similar names – such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs, and crab lice – are not true crabs, but many have evolved features similar to true crabs in a process of carcinisation.
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.
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.
Leptuca pugilator, the sand fiddler crab is a species of fiddler crab that is found from Massachusetts to the Gulf of Mexico. It lives in burrows in coastal and estuarine mud-flats, and can be extremely abundant. It can be differentiated from its congeners Minuca pugnax and Minuca minax by the smoothness of the inside of its claws. One claw is larger than the other, and can be much larger than the crab's body, at up to 41 mm (1.6 in) long.
Minuca pugnax, commonly known as the Atlantic marsh fiddler crab, is a species of fiddler crab that lives on north-western shores of the Atlantic Ocean.
Austruca mjoebergi is a species of fiddler crab discovered by and named after the Swedish zoologist Eric Mjöberg (1882–1938), member of a Swedish scientific expedition to Australia in the early 1900s.
Austruca perplexa is a species of fiddler crab. It is found from the Ryukyu Islands, Japan to India, throughout the Malay Archipelago, along eastern Australian coasts from Queensland to New South Wales, and in various Pacific islands, including Fiji, Tonga and Vanuatu.
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 U. vocans have been recognised, with their authors often granting them the taxonomic rank of full species or subspecies.
Afruca tangeri is a species of fiddler crab that lives along the Atlantic coasts of southwestern Europe and western Africa.
Paraleptuca chlorophthalmus, is a common fiddler crab found in the mangroves of East Africa, from Somalia to South Africa, as well as Madagascar and Mauritius. Marsh fiddlers dig burrows in the muddy or sandy banks of salt marshes, which they use to protect themselves from predators, high tide and extreme temperatures. They feed by filtering detritus out of mud, and defend their burrows against other fiddler crabs. Paraleptuca chlorophthalmus is characterised by its red pereiopods and blue and black markings on its carapace.
Austruca annulipes is a species of fiddler crab found along the coastline from South Africa to Somalia, Madagascar, India, China, Indonesia, Malaysia and the Philippines.
Paraleptuca crassipes or the thick-legged fiddler crab is a species of fiddler crab that lives in intertidal habitats distributed across the western Pacific Ocean.
Minuca minax, commonly known as the red‐jointed fiddler crab or brackish-water fiddler crab, is a species of fiddler crab that is found in the United States from Massachusetts to the Gulf of Mexico. It is one of the most common macroinvertebrates in salt marshes in these states. It prefers areas of lower salinity than other fiddler crabs, and can be found in great numbers along the banks of tidal streams, even at distances greater than 50 km (31 mi) from the sea.
Tubuca urvillei is a species of fiddler crab. It is found in the Southeastern Africa from southern Somalia to the South Africa and Madagascar.
Tubuca alcocki is a species of fiddler crab. Its range includes most of the northern Indian Ocean, from western Thailand, through the Bay of Bengal and India, to the Red Sea.
Tubuca flammula, commonly known as the flame-backed fiddler crab is a species of fiddler crab that is found in the northwest of Western Australia, the northern part of the Northern Territory and the western half of Papua New Guinea
Minuca longisignalis, the longwave gulf fiddler, is a species of American broad-front fiddler crab in the family Ocypodidae.
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.
Austruca is a genus of indo-west Pacific fiddler crabs in the family Ocypodidae. There are about 13 described species in this genus.
