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 freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period.
Rhithropanopeus harrisii is a small omnivorous crab native to Atlantic coasts of the Americas, from New Brunswick to Veracruz.
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 European green crab.
The Jonah crab is a marine brachyuran crab that inhabits waters along the east coast of North America from Newfoundland to Florida. Jonah crabs possess a rounded, rough-edged carapace with small light spots, and robust claws with dark brown-black tips. The maximum reported carapace width for males is 222 mm, while females rarely exceed 150 mm. It is the closest relative to the European brown crab in the Western Atlantic.
Hemigrapsus sexdentatus, also called the “common rock crab” or “common shore crab,” is a marine crab indigenous to the southern shores of New Zealand. This crab is a member of the Varunidae family in the order Decapoda.
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.
The smooth shore crab is a marine large-eyed crab of the family Grapsidae, found in New Zealand and the Juan Fernández Islands of Chile.
Charybdis is a genus of swimming crabs in the family Portunidae. It is named after the monster Charybdis of Greek mythology.
The Grapsoidea are a superfamily of crabs; they are well known and contain many taxa which are terrestrial (land-living), semiterrestrial, or limnic. Another well-known member with a more conventional lifestyle is the Chinese mitten crab, Eriocheir sinensis.
The Varunidae are a family of thoracotrematan crabs. The delimitation of this family, part of the taxonomically confusing Grapsoidea, is undergoing revision. For a long time, they were placed at the rank of subfamily in the Grapsidae, but they appear to be closest to Macropthalmus and the Mictyridae, which are usually placed in the Ocypodoidea. It may thus be better to merge the latter superfamily with the Grapsoidea, retaining the latter name as it is older.
Hemigrapsus takanoi, the brush-clawed shore crab or Asian shore crab, is a small crab of the family Varunidae that lives on rocky shores surrounding the Pacific Ocean, and which is invasive along the European coastlines. This crab is omnivorous and eats small fish, invertebrates and algae.
Helice tridens is a species of crab which lives on mudflats around the coasts of Japan and the Korean Peninsula.
Pachygrapsus marmoratus is a species of crab, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea, the Mediterranean Sea and parts of the Atlantic Ocean. It is dark violet brown, with yellow marbling, and with a body up to 36 millimetres (1.4 in) long. A semiterrestrial omnivore, it feeds on algae and various animals including mussels and limpets.
Hemigrapsus estellinensis is an extinct species of crab, formerly endemic to the Texas Panhandle. It was discovered by Gordon C. Creel in 1962 and was probably already extinct before his description was published in 1964, after the Estelline Salt Springs where it lived were contained by the United States Army Corps of Engineers. H. estellinensis is closely related to species from the Pacific Ocean such as Hemigrapsus oregonensis, but lived 800 km (500 mi) inland in a hypersaline spring. It differed from its relatives by the pattern of spots on its back, and by the relative sizes of its limbs.
Hemigrapsus is a genus of varunid crabs comprising thirteen species native almost exclusively in the Pacific Ocean, but two have been introduced to the North Atlantic region.
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.
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.
Potamon ibericum is a Eurasian species of freshwater crab. It is an omnivore that feeds on land, but returns regularly to the water, and can survive short periods of drought in burrows and under stones. Its natural range stretches from north-eastern Greece, around both sides of the Black Sea and to beyond the Caspian Sea; populations have also been introduced to southern France. It is included as a near threatened species on the IUCN Red List, and is included in the Red Data Book for Ukraine.
Hemigrapsus penicillatus is a species of crab. The native range of Hemigrapsus penicillatus extends from the Russian Far East along the coasts of Japan, China, Taiwan and Korea, as far south-west as Hong Kong. Although the species was reported from Hawaii in 1903, this is likely to have been an error; there are no recent records of the species in the central Pacific. Reports of H. penicillatus on the coasts of Europe refer to a related species, H. takanoi, which was only distinguished from H. penicillatus in 2005, several years after its discovery in Europe. Hemigrapsus penicillatus lives in the intertidal zone on stony or muddy shores.
Polyascus is a genus of barnacles in infraclass Rhizocephala. It was circumscribed in 2003 by Henrik Glenner, Jørgen Lützen, and Tohru Takahashi. They included three species, all transferred from Sacculina. The generic name polyascus refers to the typical presence of multiple external sac-like female bodies, known as externae. In Polyascus species, these originate from asexual reproduction.
