Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period.
The greater short-toed lark is a small passerine bird. The current scientific name is from Ancient Greek. The genus name, Calandrella, is a diminutive of kalandros, the calandra lark, and brachydactila is from brakhus, "short", and daktulos, "toe".
The Japanese spider crab is a species of marine crab that lives in the waters around Japan. It has the largest leg-span of any arthropod. It goes through three main larval stages along with a prezoeal stage to grow to its great size.
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.
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.
Carcinus maenas is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name green crab or European green crab. In Australia and New Zealand, it is referred to as either the European green crab or European shore crab.
Carcinus aestuarii, also known as the Mediterranean green crab is a littoral crab, native to the Mediterranean Sea.
Maja squinado is a species of migratory crab found in the north-east Atlantic and the Mediterranean Sea. The look of the European spider crab is similar to the much larger Japanese spider crab.
Majidae is a family of crabs, comprising around 200 marine species inside 52 genera, with a carapace that is longer than it is broad, and which forms a point at the front. The legs can be very long in some species, leading to the name "spider crab". The exoskeleton is covered with bristles to which the crab attaches algae and other items to act as camouflage.
Maja is a genus of majid crabs erected by Jean-Baptiste Lamarck in 1801. It includes the following extant species:
The Majoidea are a superfamily of crabs which includes the various spider crabs.
Lithodes maja, the Norway king crab, is a species of king crab which occurs in colder North Atlantic waters off Europe and North America. It is found along the entire coast of Norway, including Svalbard, ranging south into the North Sea and Kattegat, the northern half of the British Isles, and around the Faroe Islands, Iceland, and off south-eastern Greenland. In the West Atlantic, it ranges from the Davis Strait between Greenland and Canada south to The Carolinas in the United States.
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.
Liocarcinus depurator, sometimes called the harbour crab or sandy swimming crab, is a species of crab found in the North Sea, Atlantic Ocean, Mediterranean Sea, and Black Sea. It grows up to 50 millimetres (2.0 in) in width and 40 mm (1.6 in) long, and can be distinguished from other crabs, such as the shore crab Carcinus maenas, by the curved rows of white spots on its carapace.
Isaea is a small genus of amphipod crustaceans that live commensally on the mouthparts of other crustaceans.
Calliactis parasitica is a species of sea anemone associated with hermit crabs. It lives in the eastern Atlantic Ocean and Mediterranean Sea at depths between the intertidal zone and 60 m (200 ft). It is up to 10 cm × 8 cm in size, with up to 700 tentacles, and is very variable in colour. The relationship between C. parasitica and the hermit crab is mutualistic: the sea anemone protects the hermit crab with its stings, and benefits from the food thrown up by the hermit crab's movements.
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.
Around 65 species of crab occur in the waters of the British Isles. All are marine, with the exception of the introduced Chinese mitten crab, Eriocheir sinensis, which occurs in fresh and brackish water. They range in size from the deep-water species Paromola cuvieri, which can reach a claw span of 1.2 metres, to the pea crab, which is only 4 mm (0.16 in) wide and lives inside mussel shells.
Distomus variolosus is a species of tunicate or sea squirt in the family Styelidae. It is native to the northeastern Atlantic Ocean where it lives on the seabed, typically on the stems and fronds of kelp.
