Dyspanopeus sayi | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Decapoda |
Suborder: | Pleocyemata |
Infraorder: | Brachyura |
Family: | Panopeidae |
Genus: | Dyspanopeus |
Species: | D. sayi |
Binomial name | |
Dyspanopeus sayi (S. I. Smith, 1869) | |
Synonyms [1] | |
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Dyspanopeus sayi is a species of mud crab that is native to the Atlantic coast of North America. It has also become established outside its native range, living in Swansea Docks since 1960, the Mediterranean Sea since the 1970s, the North Sea since 2007 and the Black Sea since 2010. It can reach a carapace width of 20 mm (0.8 in), and has black tips to its unequal claws. It feeds on bivalves and barnacles, and is in turn eaten by predators including the Atlantic blue crab, Callinectes sapidus . Eggs are produced from spring to autumn, the offspring reach sexual maturity the following summer, and individuals can live for up to two years. The closest relative of D. sayi is D. texanus , which lives in the Gulf of Mexico; the two species differ in subtle features of the genitalia and the last pair of walking legs.
Dyspanopeus sayi is a small crab, similar in appearance to Eurypanopeus depressus . [2] It reaches a maximum carapace width of 20 millimetres (0.8 in), with sexually mature females having a carapace 6.1 millimetres (0.24 in) or more across. [3] The carapace is roughly hexagonal, about 1.3–1.4 times as wide as long and strongly convex. [2] It has a finely granular surface, [4] and has a light covering of hair, especially towards the front and sides. [2] The chelae (claws) are unequal: the right claw is stouter, and the left claw is narrower. [4] The carapace is olive-green to brown, but the tips of the claws are black. [4]
The natural range of D. sayi extends from the Baie des Chaleurs (eastern Canada) to the Florida Keys (south-eastern United States), [5] where it lives from the intertidal zone down to depths of 46 metres (151 ft). [6] It tolerates a wide range of temperatures and salinities. [6]
D. sayi has also been recorded from a number of locations in Europe. The first sighting was in Swansea Docks, South Wales (United Kingdom) in 1960, and the scientist who reported it, E. Naylor, believed there was "no doubt" that the species had arrived through trans-Atlantic shipping. [7] The first record from the Mediterranean Sea was made in 1993, when the species was discovered in the Venetian Lagoon (north-eastern Italy), [5] although it is thought to have been living there since the late 1970s. [4] In 2007, D. sayi was recorded from the North Sea coast of the Netherlands. [8] It was discovered in the Black Sea in 2010, living in Constanța harbour (Romania), [9] and in the Ebro delta of the Balearic Sea (western Mediterranean Sea) in 2012. [6]
Dyspanopeus sayi lives predominantly on muddy bottoms, [2] where it is a predator of bivalve molluscs. [6] In its native environment, it hides among colonies of polychaetes to avoid being preyed on by the Atlantic blue crab, Callinectes sapidus . [3] It is an important predator of the quahog, Mercenaria mercenaria , in Narragansett Bay, and of the barnacle Balanus improvisus in Delaware Bay. [2] In the Adriatic Sea, it has been observed to feed on the striped venus clam, Chamelea gallina , and the introduced Asian date mussel, Musculista senhousia . [10]
The life cycle of D. sayi begins with copulation, which normally takes place shortly after the female has moulted, while her exoskeleton is still soft. [11] Spawning occurs within hours or days of copulation, and the eggs are brooded on the female's pleopods (swimmerets) until they are ready to hatch. Females have been found carrying eggs from April to October; [2] in a study of crabs caught at Gloucester Point, Virginia in 1978, females were observed to carry between 686 and 14,735 eggs. The number of eggs increases with carapace width according to a power law; extrapolation of the power law suggests that the largest D. sayi females are capable of carrying over 32,000 eggs each. [11]
At 29 °C (84 °F), the eggs can take only 9 or 10 days to develop, and this increases to 16 days at temperatures of 20 °C (68 °F). [11] The young crabs hatch as zoea larvae, and pass through three further zoeal stages and one megalopa before becoming juveniles. [6] Juveniles are thought to reach maturity in the summer after they hatch. [2] The total lifespan of an individual can be up to 2 years. [3]
The species had been noticed by the American zoologist Thomas Say, and formed part of the species he called "Cancer panope" – a junior homonym of "Cancer panope" Herbst, 1801, [12] which is itself a junior synonym of Sphaerozius scaber (Fabricius, 1798). [13] In 1869, Sidney Irving Smith described seven new species in the genus Panopeus , including "P. sayi", in addition to the twelve species already placed in the genus at that time. [12] Common names for the species include "Say's mud crab" and "Say mud crab".
Smith noted the similarity of the species to "Panopeus texanus", which had been described ten years earlier by William Stimpson, and Smith considered that the two might be the same species. [12] In 1880, John Sterling Kingsley and Alphonse Milne-Edwards independently synonymised "P. sayi" with "P. texana", which remained until Mary J. Rathbun moved both taxa to the genus Neopanope and re-established Smith's taxon as a subspecies of "N. texana". [14] She argued that the two taxa should be considered subspecies, as hybrids between them occurred, although the specimens she saw are now thought to be D. sayi. [14]
In 1972, Lawrence G. Abele re-examined "N. texanus texanus", "N. texanus sayi" and N. packardi , and concluded that they were all good species, and so re-elevated "N. sayi" to the rank of species. [14] In 1986, Joel W. Martin and Abele placed N. texanus and N. sayi in a separate genus, Dyspanopeus , reaffirming their close relationship. [15] However, P. texana only occurs in the Gulf of Mexico, and can be distinguished from P. sayi by the form of the fifth pereiopod (last walking leg) and that of the male gonopod. [16]
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.
Cancer pagurus, commonly known as the edible crab or brown crab, is a species of crab found in the North Sea, North Atlantic Ocean, and perhaps the Mediterranean Sea. It is a robust crab of a reddish-brown colour, having an oval carapace with a characteristic "pie crust" edge and black tips to the claws. A mature adult may have a carapace width up to 25 centimetres and weigh up to 3 kilograms. C. pagurus is a nocturnal predator, targeting a range of molluscs and crustaceans. It is the subject of the largest crab fishery in Western Europe, centred on the coasts of the British Isles, with more than 60,000 tonnes caught annually.
Portunus pelagicus, also known as the blue crab, blue swimmer crab, blue manna crab and flower crab is a species of large crab found in the Indo-Pacific, including off the coasts Indonesia, Malaysia, Cambodia, Thailand, the Philippines, and Vietnam; and in the intertidal estuaries around most of Australia and east to New Caledonia.
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.
Menippe adina is a species of crab, sometimes called the Gulf stone crab or Western Gulf stone crab. It is very closely related to the Florida stone crab, Menippe mercenaria, of which it is sometimes considered to be a subspecies.
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.
Pilumnus hirtellus, the bristly crab or hairy crab, is a species of European crab. It is less than 1 inch (25 mm) long and covered in hair. It lives in shallow water and feeds on carrion.
Pisidia longicornis, the long-clawed porcelain crab, is a species of porcelain crab that lives in the north-eastern Atlantic Ocean. It varies from reddish to white, and grows to a carapace width of 1 cm (0.4 in). It was first named by Carl Linnaeus in 1767, although the etymology remains unclear.
Xantho hydrophilus, the furrowed crab or Montagu's crab, is a species of crab from the family Xanthidae. It is yellowish-brown and grows to a carapace width of 70 mm (2.8 in). It is a nocturnal omnivore that lives in shallow marine waters from western Scotland to the Cape Verde Islands.
Paromola cuvieri is a species of crab in the family Homolidae, the carrier crabs. It occurs in the eastern Atlantic Ocean and the Mediterranean Sea, from Angola to Norway, the Northern Isles and Iceland. It is demersal, occurring at depths of 10–1,212 metres (33–3,976 ft), but it is primarily found deeper than 80 m (260 ft). It prefers areas with mud and emerging rocks, and has been observed in deep-water coral gardens and sponge aggregations. It is locally common.
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
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.
Dyspanopeus is a genus of crabs in the family Panopeidae, comprising two species:
Brachynotus sexdentatus is a species of crab in the family Varunidae. It is native to the Mediterranean Sea and Black Sea, and became established for a time in Swansea Docks. It grows to a maximum carapace width of 18 mm (0.71 in), and lives in shallow water on muddy bottoms.
Dyspanopeus texanus is a species of crab known as the Texas mud crab.
Loxothylacus panopaei is a species of barnacle in the family Sacculinidae. It is native to the Gulf of Mexico and the Caribbean Sea. It is a parasitic castrator of small mud crabs in the family Panopeidae, mostly in the Gulf of Mexico, the Caribbean Sea and the eastern Atlantic Ocean.
Panopeus lacustris, the knot-fingered mud crab, is a true crab belonging to the infraorder Brachyura. It can be distinguished from related species by its exceptionally broad and knobbly main chela (claw).
Eurypanopeus depressus, the flatback mud crab or depressed mud crab, is a true crab belonging to the infraorder Brachyura and the family Panopeidae. It is native to the western Atlantic Ocean and is often found in estuaries and lagoons, commonly living in close association with oysters.
Armases cinereum, also known as the squareback marsh crab or wharf crab, is a species of crab in the family Sesarmidae. The wharf crab is a small crab that is dark brown to muddy in color, which allows it to blend in with its usual surroundings. It is found on the Atlantic southeastern coast, down into the Gulf of Mexico. It is an omnivore and is prevalent in marshy coastal environments along the Southwestern Atlantic.