Portal:Crustaceans

The Crustaceans Portal

Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (/krəˈsteɪʃə/), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), 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 (insects and entognathans) 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 (oligostracans and multicrustaceans).

The 67,000 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 3.8 m (12.5 ft) and a mass of 20 kg (44 lb). Like other arthropods, crustaceans have an exoskeleton, which they moult 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 their larval forms, such as the nauplius stage of branchiopods and copepods.

Most crustaceans are free-living aquatic animals, but some are terrestrial (e.g. woodlice, sandhoppers), some are parasitic (e.g. Rhizocephala, fish lice, tongue worms) and some are sessile (e.g. barnacles). The group has an extensive fossil record, reaching back to the Cambrian. More than 7.9 million tons of crustaceans per year are harvested by fishery or farming for human consumption, consisting mostly of shrimp 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. The scientific study of crustaceans is known as carcinology (alternatively, malacostracology, crustaceology or crustalogy), and a scientist who works in carcinology is a carcinologist. (Full article...)

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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.

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Did you know?

... that Cameroon is named after the ghost shrimp Lepidophthalmus turneranus (pictured) which Portuguese settlers observed swarming in the Wouri River in the 15th century?
... that the porcelain crab Pisidia longicornis is sometimes found among mussels and oysters in European fish markets?
... that the meat of the slipper lobster Ibacus peronii is considered inferior to that of the Moreton Bay bug because it sometimes tastes of garlic?
... that Tanymastix stagnalis is the only species of fairy shrimp to occur in Ireland?

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Charles Chilton (1860–1929) was a New Zealand zoologist, the first rector to be appointed in Australasia, and the first person to be awarded a D.Sc. degree in New Zealand.

Chilton was born on September 27, 1860 at Little Marstone, Pencombe (near Leominster, Herefordshire, England) but emigrated with his family to New Zealand in 1862. They settled on a farm at East Eyreton, North Canterbury. He was troubled by his hips from an early age, and had his left leg amputated, using an artificial leg and a crutch thereafter. In 1881, he gained an M.A. with first class honours from Canterbury College, having been taught by Frederick Wollaston Hutton, who inspired him to take up biology, especially the study of crustaceans, which had been little studied in New Zealand up to that time.

Chilton's first scientific publication followed that same year, when he described three new species of crustacean (two crabs and one isopod) from Lyttelton Harbour and Lake Pupuke. He surprised the scientific world later that year by describing four species of amphipod and isopod from groundwaters at the family farm in Eyreton. He went on to discover the isopod Phreatoicus typicus in the same location, the first example ever described of the suborder Phreatoicidea, the "earliest derived isopod[s]".

Charles Chilton became rector of Christchurch University College in 1921, the first time such a post had been granted in Australia or New Zealand. Chilton died on October 25, 1929 of a sudden attack of pneumonia, before he could collect his life's work into a single monograph. He had published 130 papers on crustaceans, mostly amphipods, isopods and decapods, from all around the world, but especially from New Zealand, subterranean and sub-Antarctic waters.

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Triops longicaudatus (Branchiopoda: Anostraca)

Credit: Micha L. Rieser

Triops longicaudatus (left: dorsal; right: ventral) is a species of tadpole shrimp which has existed since the Triassic.

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General images

The following are images from various crustacean-related articles on Wikipedia.

Image 1The large ostracod Herrmannina from the Silurian (Ludlow) Soeginina Beds (Paadla Formation) on eastern Saaremaa Island, Estonia (from Ostracod)
Image 2Copepods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 3Articulated ostracod valves in cross-section from the Permian of central Texas; typical thin section view of an ostracod fossil (from Ostracod)
Image 4Cancer pagurus (Eucarida: Decapoda) (from Malacostraca)
Image 5Abludomelita obtusata, an amphipod (from Crustacean)
Image 6Ostracod (from Ostracod)
Image 7Grapsus grapsus, a terrestrial crab (from Malacostraca)
Image 8Porcellio scaber and Oniscus asellus (Peracarida: Isopoda) (from Malacostraca)
Image 9Squilla empusa,
a mantis shrimp (from Malacostraca)
Image 10Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 11Norway lobsters on sale at a Spanish market
Image 12Leptostraca such as Nebalia bipes retain the primitive condition of having seven abdominal segments. (from Malacostraca)
Image 13Ostracod swimming motions (in real time) (from Ostracod)
Image 14Zoea larva of the European lobster, Homarus gammarus
Image 15Odontodactylus scyllarus (Hoplocarida: Stomatopoda) (from Malacostraca)
Image 16Artemia salina (Anostraca: Artemiidae) (from Branchiopoda)
Image 17Anatomy of Cypridina mediterranea (from Ostracod)
Image 18Daphnia pulex (Cladocera: Daphniidae) (from Branchiopoda)
Image 19A shed carapace of a lady crab, part of the hard exoskeleton
Image 20Body structure of a typical crustacean – krill (from Crustacean)
Image 21Eryma mandelslohi, a fossil decapod from the Jurassic of Bissingen an der Teck, Germany
Image 22Eggs of Potamon fluviatile, a freshwater crab