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.
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, 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. 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, swamps, and various other types of brackish or salt-water wetlands.
Leptuca pugilator, the sand fiddler crab, Atlantic sand fiddler crab, or Calico fiddler, 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 the morphologically similar 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 G. 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 western Africa and southwestern Europe.
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 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
Australoplax tridentata, commonly known as the furry-clawed crab or tuxedo shore crab is a species of crab in the family Macrophthalmidae that is found in Queensland, New South Wales and the Northern Territory.
Helopgrapsus haswellianus or Haswell’s shore crab, is the sole species of crab in the genus Helograpsus. It lives in river mouths and bays on the eastern coast of Australia. The carapace is strongly convex with one distinct notch behind the eye. Adult males have larger claws than adult females. The carapace is olive, dark slate grey or reddish. Claws of adult males are orange-yellow. Carapace size is up to 30 mm wide. The orange color is stronger when these crabs live in habitat with lower pollution levels.
Tubuca polita, commonly known as the polished fiddler crab. or pink-clawed fiddler crab is a species of fiddler crab that is found in the northern part of Australia including the Torres Strait Islands
Tubuca coarctata is a species of fiddler crab found in the western Pacific ocean, including Japan, Taiwan, the Philippines, Indonesia, New Guinea and Australia. The common name of these crabs is either the compressed fiddler crab, or the orange-clawed fiddler crab,. They are found on tidal mud flats adjacent mangroves and muddy tidal creek and river banks.
Tubuca dussumieri, is a species of fiddler crab that is found in the western and south pacific including New Caledonia, Indonesia, Malaysia, Taiwan, Japan, north eastern Australia
Tubuca signata, the signalling fiddler crab, is a species of fiddler crab that is found in Australia from Queensland to northwestern Australia.
Tubuca capricornis, the capricorn fiddler crab, is a species of fiddler crab that is found in north west and northern Australia. It was named after its occurrence near the Tropic of Capricorn. These crabs live on shaded mud flats in mangroves.
