Portal:Crustaceans

The Crustaceans Portal

Crustaceans (from Latin word "crustacea" meaning: "those with shells" or "crusted ones") are mandibulate arthropods that are traditionally a part of the paraphyletic subphylum Crustacea (/krəˈsteɪʃə/). Crustaceans are mainly aquatic, including decapods (shrimps, prawns, crabs, lobsters, and crayfish), seed shrimps, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. It is now well accepted that hexapods (insects and entognathans) are cladistically crustaceans, with the two groups now combined in the monophyletic clade Pancrustacea. The three classes Cephalocarida, Branchiopoda, and Remipedia are more closely related to the hexapods than they are to any 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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Fossil of P. pustulosus at the Jura Museum

Pseudastacus (meaning 'false Astacus', in comparison to the extant crayfish genus) is an extinct genus of decapod crustaceans that lived during the Jurassic period in Europe, and possibly the Cretaceous period in Lebanon. Many species have been assigned to it, though the placement of some species remains uncertain and others have been reassigned to different genera. Fossils attributable to this genus were first described by Georg zu Münster in 1839 under the name Bolina pustulosa, but the generic name was changed in 1861 after Albert Oppel noted that it was preoccupied. The genus has been placed into different families by numerous authors, historically being assigned to Nephropidae or Protastacidae. Currently, it is believed to be a member of Stenochiridae.

Reaching up to 6 cm (2.4 in) in total length, Pseudastacus individuals were small animals. Members of this genus have a crayfish-like build, possessing long antennae, a triangular rostrum and a frontmost pair of appendages enlarged into long and narrow pincers. Deep grooves are present on the carapace, which is around the same length as the abdomen. The surface of the carapace is usually uneven, with either small tubercles or pits. Sexual dimorphism is known in P. pustulosus, with the pincers of females being more elongated than those of the males. There is evidence of possible gregarious behavior in P. lemovices in the form of multiple individuals preserved alongside each other, possibly killed in a mass mortality event. With the oldest known record dating to the Sinemurian age of the Early Jurassic, and possible species surviving into the Cenomanian stage of the Late Cretaceous, Pseudastacus has a long temporal range and was a widespread taxon. Fossils of these animals were first found in the Solnhofen Limestone of Germany, but have also been recorded from France, England and Lebanon. All species in this genus lived in marine environments. (Full article...)

Did you know?

... that, during the breeding season, the male blueband hermit crab (pictured) carries the female around for up to a day?
... that Aenigmastacus, a fossil crayfish from Canada, belongs to a family only otherwise known from the Southern Hemisphere?
... that the New Zealand lobster was incorporated into the country's Quota Management System after a parliamentary corruption scandal?
... that Balanus perforatus is a barnacle shaped like a volcano?

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Robert Gurney (July 31, 1879 – March 5, 1950) was a British zoologist most famous for his monographs on British Freshwater Copepoda (1931–1933) and the Larvae of Decapod Crustacea (1942). He was born in 1879 as the fourth son of John Gurney and Isabel Charlotte Gurney (later Baroness Talbot de Malahide) of Sprowston Hall, Norfolk. He went to school at Eton College, and went on to study at New College, Oxford, graduating with first class honours in 1902. He was never associated with any institution, but worked from his home, initially in Norfolk, but later at Boars Hill. Realising the need for a specialist field station for freshwater biology to match the marine biological stations at Plymouth and Naples, Robert and his brother Eustace set up Great Britain's first freshwater laboratory at Sutton Broad. Gurney's two great study objects were the Copepoda and the larvae of Decapoda (zoea larva of Homarus gammarus pictured), and his greatest works were the three-volume monograph British Freshwater Copepoda, published by the Ray Society in 1931–1933, and his Larvae of Decapod Crustacea published by the Ray Society in 1942. Gurney travelled to North Africa and Bermuda, and received material from other foreign expeditions, including the Terra Nova Expedition (1910–1913) and the Discovery Investigations of the 1920s and 1930s.

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Credit: Hans Hillewaert

Eurydice pulchra, the speckled sea louse, is a species of isopod crustacean found in the northeast Atlantic Ocean.

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General images

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

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