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. They are generally covered with a thick exoskeleton. They generally have five pairs of legs, and they have pincer claws on the ends of the frontmost pair. They first appeared during the Jurassic period, around 200 million years ago.
Homarus gammarus, known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, H. americanus. It may grow to a length of 60 cm (24 in) and a mass of 6 kilograms (13 lb), and bears a conspicuous pair of claws. In life, the lobsters are blue, only becoming "lobster red" on cooking. Mating occurs in the summer, producing eggs which are carried by the females for up to a year before hatching into planktonic larvae. Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots, mostly around the British Isles.
Isopoda is an order of crustaceans. Members of this group are called isopods and include both aquatic species, and terrestrial species such as woodlice. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax called the marsupium.
The Japanese spider crab is a species of marine crab and is the biggest one that lives in the waters around Japan. At around 3.7 meters, it has the largest leg-span of any arthropod. The Japanese name for this species is taka-ashi-gani,, literally translating to “tall legs crab”. It goes through three main larval stages along with a prezoeal stage to grow to its great size.
Nephrops norvegicus, known variously as the Norway lobster, Dublin Bay prawn, langoustine or scampi, is a slim, coral colored lobster that grows up to 25 cm (10 in) long, and is "the most important commercial crustacean in Europe". It is now the only extant species in the genus Nephrops, after several other species were moved to the closely related genus Metanephrops. It lives in the north-eastern Atlantic Ocean, and parts of the Mediterranean Sea, but is absent from the Baltic Sea and Black Sea. Adults emerge from their burrows at night to feed on worms and fish.
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 Ireland and Britain, with more than 60,000 tonnes caught annually.
The Tasmanian giant crab, also known as the giant deepwater crab, giant southern crab, queen crab, or bullcrab, is a very large species of crab that resides on rocky and muddy bottoms in the oceans off Southern Australia. It is the only extant species in the genus Pseudocarcinus.
Maja brachydactyla is a species of crab in the family Majidae. It was initially described as a subspecies of M. squinado. A review of the species complex published in 1998 was able to differentiate between specimens from the Mediterranean Sea and those from the Atlantic Ocean, and concluded that the Atlantic specimens were a separate species, accepted as M. brachydactyla Balss, 1922.
The Majoidea are a superfamily of crabs which includes the various spider crabs.
Ovalipes catharus, commonly known as the paddle crab, swimming crab, or Māori: pāpaka, is a species of crab in the family Ovalipidae. They are found in shallow, sandy-bottomed waters around the coasts of New Zealand, the Chatham Islands, and uncommonly in southern Australia. They are opportunistic and versatile feeders active mostly at night, preying predominantly on molluscs and crustaceans. They are also highly prone to cannibalism both as part of their regular diet and as part of their mating behaviour. Their paddle-shaped rear legs and streamlined carapace allow them to swim rapidly to capture prey and to burrow in the sand in order to escape predation. Their mating season is in winter; the male carries the female until she moults, after which the two mate and the female moves into deeper waters to disperse her larvae.
Crab fisheries are fisheries which capture or farm crabs. True crabs make up 20% of all crustaceans caught and farmed worldwide, with about 1.4 million tonnes being consumed annually. The horse crab, Portunus trituberculatus, accounts for one quarter of that total. Other important species include flower crabs, snow crabs (Chionoecetes), blue crabs, edible or brown crabs, Dungeness crab, and mud crabs, each of which provides more than 20,000 tonnes annually.
Scyllarides latus, the Mediterranean slipper lobster, is a species of slipper lobster found in the Mediterranean Sea and in the eastern Atlantic Ocean. It is edible and highly regarded as food, but is now rare over much of its range due to overfishing. Adults may grow to 1 foot (30 cm) long, are camouflaged, and have no claws. They are nocturnal, emerging from caves and other shelters during the night to feed on molluscs. As well as being eaten by humans, S. latus is also preyed upon by a variety of bony fish. Its closest relative is S. herklotsii, which occurs off the Atlantic coast of West Africa; other species of Scyllarides occur in the western Atlantic Ocean and the Indo-Pacific. The larvae and young animals are largely unknown.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
Chionoecetes opilio, a species of snow crab, also known as opilio crab or opies, is a predominantly epifaunal crustacean native to shelf depths in the northwest Atlantic Ocean and north Pacific Ocean. It is a well-known commercial species of Chionoecetes, often caught with traps or by trawling. Seven species are in the genus Chionoecetes, all of which bear the name "snow crab". C. opilio is related to C. bairdi, commonly known as the tanner crab, and other crab species found in the cold, northern oceans.
The curled octopus, also known as the horned octopus, lesser octopus or northern octopus, is a species of cephalopod found in the northeast Atlantic, ranging from Norway to the Mediterranean, including the British Isles. The total length of an adult is around 50 cm, but their arms are often tightly curled. It immobilises and eats large crustaceans by drilling a hole through their shell. It is mainly by-catch in commercial fisheries of the north eastern Atlantic and Mediterranean, where the common octopus is the preferred species.
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.
Macropodia rostrata, common names, the common spider crab, long-legged spider crab, long-legged crab, is a species of marine crab in the family Inachidae. The Macropodia Rostrata visually mimics many other types of small crabs with the exception of its long legs. By attaching algae to their thin legs, they can be confused with the stem of seaweed. This is both a defense mechanism and a predatory advantage, as unsuspecting fish will hide in seaweed beds from nearby predators. This behavior can be absent among larger crabs, and those that live at great depths like giant Japanese spider crabs.
Ibacus alticrenatus is a species of slipper lobster that lives in the waters of Australia and New Zealand.
Crustaceans are invertebrate animals that constitute one group of arthropods that are a part of the subphylum Crustacea, a large, diverse group of mainly aquatic arthropods including decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans.
Aristaeomorpha foliacea, the giant red shrimp or giant gamba prawn, is a species of deep water benthopelagic decapod crustacean. It is found in all the world's oceans in the temperate and tropical zones. It is subject to some commercial fishing activity in the Mediterranean Sea.
