Portal:Crustaceans

The Crustaceans Portal

Crustaceans (from Latin word "crustacea" 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 the more familiar decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimps, 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...)

Selected article

The Cape lobster, Homarinus capensis, is a species of small lobster that lives off the coast of South Africa, from Dassen Island to Haga Haga. Only a few dozen specimens are known, mostly regurgitated by reef-dwelling fish. It lives in rocky reefs, and is thought to lay large eggs that have a short larval phase, or that hatch directly as a juvenile. The species grows to a total length of 10 cm (3.9 in), and resembles a small European or American lobster; it was previously included in the same genus, Homarus, although it is not very closely related to those species, and is now considered to form a separate, monotypic genus – Homarinus. Its closest relatives are the genera Thymops and Thymopides.

Did you know?

... that all that remains of the type specimen of the Mediterranean slipper lobster is a 16th century watercolour (pictured)?
... that the blind crustacean Polycheles typhlops preys on fish and on other crustaceans, probably acting as an ambush predator?
... that Edward J. Miers was paid 60 guineas for his monograph on the crabs of the Challenger expedition?
... that the genus Platythelphusa represents the only evolutionary radiation of crabs to have occurred in a freshwater lake?

Selected biography

The Reverend Thomas Roscoe Rede Stebbing F.R.S., F.L.S. (February 6, 1835 – July 8, 1926) was a British zoologist, who described himself as "a serf to natural history, principally employed about Crustacea".

Having trained as an evangelical Anglican, Stebbing expected to be a staunch opponent of Charles Darwin's recently published theory of evolution by natural selection. Following a critical review of The Descent of Man in The Times in 1871, Stebbing gained prominence by responding in Nature. Stebbing wrote a number of essays on the topic of Darwinism, in which he dissected the argument posited against it, and questioned various aspects of Christianity. His outspoken stance resulted in his being banned from preaching, and he was never offered a parish by the church.

Most of Stebbing's scientific works, comprising more than 110 papers, covered amphipod crustaceans. Stebbing produced a monograph on the amphipods collected on the 1872–1876 expedition by HMS Challenger. He also produced a monograph of the Cumacea, a natural history of the Crustacea, and a biography of the Scottish naturalist and founder of the University Marine Biological Station, Millport, David Robertson. In 1906, Stebbing published the volume on Gammaridea for the series Das Tierreich.

Selected image

Periclimenes imperator (Decapoda: Palaemonidae) is a species of shrimp with a wide distribution across the Indo-Pacific that lives commensally on a number of hosts, including the sea slug Hexabranchus.

General images

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

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