From Wikipedia, the free encyclopedia

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.

Show new selections | Go to random article

Selected article

Seychellum alluaudi (Decapoda, Potamonautidae)
Seychellum alluaudi is a species of freshwater crab endemic to the Seychelles, and the only true freshwater crab in that country. It lives in rainforest streams on the archipelago's granitic high islands. Although it may be abundant, little is known about its biology, and it is currently listed as Least Concern on the IUCN Red List. Adults are dark yellow to brown in colour, and have a quadrangular carapace with a width of around 50 mm (2 in). The claws are unequal in size.

S. alluaudi was described as a species of Deckenia in 1893 and 1894, and later split off into the monotypic segregate genus Seychellum. Its closest relatives are the two species currently in Deckenia, both of which are found in East Africa. Several hypotheses have been published to explain how Seychellum reached its isolated location; some means of transport across the open ocean is considered the most likely explanation. Seychellum differs from Deckenia in a number of characters, including the lengths of the legs and antennae, and the fact that Deckenia species have flattened legs, compared to those of Seychellum.

Did you know?

A yellowish shrimp, with one conspicuously large claw contrasting with its smaller pair.

Selected biography

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.

Associated Wikimedia

Crustacea on Wikinews  Crustacea on Wikiquote  Crustacea on Wikibooks  Crustacea on Wikisource  Crustacean on Wiktionary  Crustacea on Wikiversity  Crustacea on Wikimedia Commons
News Quotations Manuals & Texts Texts Definitions Learning resources Images & Media

Purge server cache

Retrieved from "https://en.wikipedia.org/w/index.php?title=Portal:Crustaceans&oldid=683257799"
This content was retrieved from Wikipedia : http://en.wikipedia.org/wiki/Portal:Crustaceans
This page is based on the copyrighted Wikipedia article "Portal:Crustaceans"; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA