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.
Ocypode is a genus of ghost crabs found in the sandy shores of tropical and subtropical regions throughout the world. They have a box-like body, thick and elongated eyestalks, and one claw is larger than the other in both males and females. They inhabit deep burrows in the intertidal zone. They are primarily nocturnal, and are generalist scavengers and predators of small animals. The genus contains 21 species.
Mictyris is a genus of brightly coloured crabs, placed in its own taxonomical family, the Mictyridae. It inhabits the central Indo-West Pacific region. These crabs congregate on mud flats or beaches in groups of a few thousand, and filter sand or mud for microscopic organisms. They congregate during low tide, and bury themselves in the sand during high tide or whenever they are threatened. This is done in wet sand, and they dig in a corkscrew pattern, leaving many small round pellets of sand behind them.
Sand bubbler crabs are crabs of the genera Scopimera and Dotilla in the family Dotillidae. They are small crabs that live on sandy beaches in the tropical Indo-Pacific. They feed by filtering sand through their mouthparts, leaving behind balls of sand that are broken up by the incoming high tide.
Hemigrapsus crenulatus, the hairy-handed crab or papaka huruhuru, is a marine crab of the family Varunidae, endemic to the New Zealand coast, although a taxon in Chile may be conspecific. It is an intertidal species with semi-terrestrial tendencies. They are named by their characteristic setae, or patches of thick hair, on the chelipeds and legs. They can range from green to brown in coloration. Adult crabs are generally 2–4 cm (0.8–1.6 in) wide at the carapace, although the smallest mature crabs can be around just 1 cm (0.4 in) wide. and are able to survive and reproduce in environments of widely varying salinities.
Leptograpsus variegatus, known as the purple rock crab, is a marine large-eyed crab of the family Grapsidae, found in southern subtropical Indo-Pacific Oceans. It grows to around 50 millimetres (2.0 in) shell width. It is the only species in the genus Leptograpsus.
Charybdis is a genus of swimming crabs in the family Portunidae. It is named after the monster Charybdis of Greek mythology.
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.
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.
Ocypode gaudichaudii, also known as the painted ghost crab or cart driver crab, is a species of crab found on Pacific beaches from El Salvador to Chile as well as on the Galápagos Islands. The species was first described by Henri Milne-Edwards and Hippolyte Lucas in 1843.
The Panopeidae are a family containing 26 genera of morphologically similar crabs, often known as "mud crabs". Their centers of diversity are the Atlantic Ocean and eastern Pacific Ocean.
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.
Ocypode brevicornis is a species of ghost crab native to the Indian Ocean, from the Gulf of Oman to the Nicobar Islands. They are relatively large ghost crabs with a somewhat trapezoidal body. The carapace reaches a length of 41 mm (1.6 in) and a width of 50 mm (2.0 in). They are a mottled brown to yellow in coloration. Like other ghost crabs, one of their claws is much larger than the other. Their eyestalks are large and elongated, tipped with prolongations at the tip known as styles. They are common inhabitants of open sandy beaches, living in burrows in the intertidal zone.
Calappilia is an extinct genus of box crabs belonging to the family Calappidae. The type species of the genus is Calappilia verrucosa.
The Red-claw mangrove crab is a crab species in the genus Parasesarma and the family Sesarmidae. It is distributed in coastal brackish water habitats of the western Indian Ocean.
Austruca is a genus of indo-west Pacific fiddler crabs in the family Ocypodidae. There are about 13 described species in this genus.
Libinia spinosa is a majoid crab found in mud and sand bottoms of the Southwestern Atlantic and Pacific oceans. It is a generalist feeder on organisms such as algae, sponges, cnidarians, mollusks, polychaetes, crustaceans, and small fish. It commonly engages in a symbiotic relationship with the medusa Lychnorhiza lucerna.
Pseudohelice subquadrata is a species of crab in the family Varunidae. It is found from the eastern Indian Ocean to the western Pacific Ocean, north to Japan, south to Eastern Australia, east to French Polynesia, west to Indonesia and Thailand. It lives near mangroves, burrowing in firm soils, firm muddy sand or loose stones. Burrows are towards or above the high tide line on shores of estuaries and near river mouths of bays, and can have offshoots horizontal beneath the surface as long as three metres.
