Portal:Crustaceans

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The Crustaceans Portal

Crustaceans are a group of arthropods that are 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 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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Johngarthia lagostoma is a species of terrestrial crab that lives on Ascension Island and three other islands in the South Atlantic. It grows to a carapace width of 110 mm (4.3 in) on Ascension Island, where it is the largest native land animal. It exists in two distinct colour morphs, one yellow and one purple, with few intermediates. The yellow morph dominates on Ascension Island, while the purple morph is more frequent on Atol das Rocas. The species differs from other Johngarthia species by the form of the third maxilliped.

J. lagostoma lives in burrows among vegetation, at altitudes of up to 400 m (1,300 ft), emerging at night to feed on plant matter and occasionally on animals. From January to March there is an annual migration to the sea to release the planktonic larvae. The species was first described (as Gecarcinus lagostoma) by Henri Milne-Edwards in 1837 from material sent to him by the naturalists Jean René Constant Quoy and Joseph Paul Gaimard, collected by the French ship Astrolabe.

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Did you know?

... that the gooseneck barnacle Pollicipes polymerus (several pictured) will become sterile if there are no others within 20 cm (8 in)?
... that the clawless lobster Tricarina is known from a single fossil, obtained from an oil well 3,852 m (12,638 ft) below ground in western Iran?
... that Japanese skeleton shrimp are invading the coastlines of North America, Europe, and New Zealand?
... that swarms of Japanese soldier crabs of the species Mictyris guinotae, named after French biologist Danièle Guinot, can be used in place of the billiard balls in billiard-ball computers?

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Edward J. Miers F.Z.S. F.L.S. (1851–1930) was a British zoologist and curator of the crustacean collection at the Natural History Museum in London. He contributed to the scientific reports from the Challenger expedition of 1872–1876, and described 32 new genera and at least 260 new species and subspecies of decapod crustaceans, along with four genera and 72 new species in other orders.

Miers published his Catalogue of the stalk- and sessile-eyed Crustacea of New Zealand in 1876 and revised the Plagusiinae, Hippidae, Majidae, Squillidae and Idoteidae in monographs dated 1878–1881. He also reported on the collections donated by the Admiralty from a number of voyages, including the survey of the coast of Japan by H.M.S. Sylvia (1870–1877), an expedition to view the Transit of Venus in Kerguelen and Rodrigues (1874–1875), a survey of the Galápagos Islands by H.M.S. Petrel, Novaya Zemlya by H.M.S. Isbjorn (1879), Baron Hermann-Maltzan's voyage to Gorée in 1881, and the voyages of H.M.S. Alert to Patagonia and the Strait of Magellan (1881–1882). The upheavals at his workplace and the quantity of work to be done may have taken their toll on Miers, and he was "completely prostrated with illness" for three months.

Miers was still working on material from the Alert expedition, when six boxes containing the crabs from the Challenger expedition arrived, sent by John Murray. Describing these crabs would be Miers' largest taxonomic work, one which was published in 1886 as Report on the Brachyura collected by H. M. S. Challenger during the years 1873–1876 in 1886. Miers' honorarium for this work was £63 (60 guineas).

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Credit: Hans Hillewaert

Nototropis falcatus (formerly Atylus falcatus) is a species of amphipod from sandy bottoms in the North Atlantic and North Sea.

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General images

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

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