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.
Ghost crabs are semiterrestrial crabs of the subfamily Ocypodinae. They are common shore crabs in tropical and subtropical regions throughout the world, inhabiting deep burrows in the intertidal zone. They are generalist scavengers and predators of small animals. The name "ghost crab" derives from their nocturnality and their generally pale coloration. They are also sometimes called sand crabs, though the name refers to various other crabs that do not belong to the subfamily.
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.
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.
Hemigrapsus oregonensis is a small shore crab of the family Varunidae; formerly classified under the family Grapsidae. It is known under several common names, including yellow shore crab, hairy shore crab, green shore crab, mud-flat crab, bay shore crab and Oregon shore crab. Despite its common name, the crab actually has a wide variety of coloration. It is found along the West Coast of the United States and Canada, specifically along shorelines and similar geographical areas. In 2009, H. oregonensis was included on a list of animals petitioning for the endangered species label, but there was not enough scientific information available for it to be considered as such, so it remains unevaluated to the present day.
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.
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.
The eastern swamp crayfish is a species of small freshwater crayfish from coastal New South Wales, Australia. It is distinguished from related species by large genital papilla on the males, large raised postorbital ridges, a laterally compressed carapace, and elongated chelae.
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 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
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.
Leptuca batuenta, commonly known as the beating fiddler crab, is a species of fiddler crab native to the tropical eastern Pacific, from El Salvador to northern Peru.
Gelasimus vomeris is a species of fiddler crab found in the southwest Pacific Ocean. In Australia, it is found in the east and north from Darwin to Sydney.
The sensory trap hypothesis describes an evolutionary idea that revolves around mating behavior and female mate choice. It is a model of female preference and male sexual trait evolution through what is known as sensory exploitation. Sensory exploitation, or a sensory trap is an event that occurs in nature where male members of a species perform behaviors or display visual traits that resemble a non-sexual stimulus which females are responsive to. This tricks females into engaging with the males, thus creating more mating opportunities for males. What makes it a sensory trap is that these female responses evolved in a non-sexual context, and the male produced stimulus exploits the female response which would not otherwise occur without the mimicked stimulus.
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.
