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The crustaceans portal

Abludomelita obtusata.jpg

Crustaceans (Subphylum Crustacea) form a very large group of arthropods, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at 0.1 mm (0.004 in), to the Japanese spider crab with a leg span of up to 14 ft (4.3 m) and a mass of 44 lb (20 kg). Like other arthropods, crustaceans have an exoskeleton, which they moult in order to grow. They are distinguished from other groups of arthropods, such as insects, myriapods and chelicerates by the possession of biramous (two-parted) limbs, and by the nauplius form of the larvae. Most crustaceans are free-living aquatic animals, but some are terrestrial (e.g. woodlice), some are parasitic (e.g. fish lice, tongue worms) and some are sessile (e.g. barnacles). The group has an extensive fossil record, reaching back to the Cambrian, and includes living fossils such as Triops cancriformis, which has existed apparently unchanged since the Triassic period. More than 10 million tons of crustaceans are produced by fishery or farming for human consumption, the majority of it being shrimps and prawns. Krill and copepods are not as widely fished, but may be the animals with the greatest biomass on the planet, and form a vital part of the food chain.

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Hemigrapsus estellinensis is an extinct species of crab, formerly endemic to the Texas Panhandle. It was closely related to species from the Pacific Ocean such as Hemigrapsus oregonensis, but lived 500 mi (800 km) inland in a hypersaline spring. Its occurrence so far from the ocean has been described as "curious", and it was "probably a Pleistocene relic". It differed from its relatives by the pattern of spots on its back, and by the relative sizes of its limbs. H. estellinensis 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 to reduce the salt load on the Prairie Dog Town Fork of the Red River.

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Emerita analoga (Decapoda: Hippidae)

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William Elford Leach FRS (February 2, 1790 – August 26, 1836) was an English zoologist and marine biologist. In 1813, Leach was employed as assistant librarian in the Zoological Department at the British Museum. He set himself to sorting out the collections, many of which had been neglected since they had been left to the museum by Hans Sloane. During his time there he was made assistant keeper of the natural history department and became an expert on crustaceans and molluscs. In 1817, he was elected a fellow of the Royal Society. Leach also worked and published on insects, myriapods, arachnids, mammals and birds. Leach's nomenclature was a little eccentric - he named twenty-seven species after his friend John Cranch, who had collected the species in Africa and later died on HMS Congo. In 1818, he named nine genera after Caroline or anagrams of that name, possibly after his mistress. In 1821, he suffered a nervous breakdown due to overwork, and he resigned from the museum in March 1822. His elder sister took him to continental Europe to convalesce, and they travelled through France, Italy and Greece. He died of cholera in the Palazzo San Sebastiano, near Tortona, north of Genoa.

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