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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Potamon fluviatile is a freshwater crab found in or near wooded streams, rivers and lakes in Southern Europe. It is an omnivore with broad ecological tolerances, and adults typically reach 50 mm (2 in) in size during their 10–12 year lifespan. They inhabit burrows and are aggressive, apparently outcompeting native crayfish. P. fluviatile has been harvested for food since Classical antiquity, and is now threatened by overexploitation. Many of the island populations are particularly vulnerable, and the Maltese subspecies has become a conservation icon. A population in Rome is the only population of freshwater crabs to occur in the middle of a large city, and may have been brought there before the founding of the Roman Empire.

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... 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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Mary J. Rathbun (1860–1943) was an American zoologist, specialising in crustaceans. She was born on June 11, 1860 in Buffalo, New York the youngest of five children. Her mother died when she was only one year old, and Mary was therefore "thrown on her own resources". She was schooled in Buffalo, graduating in 1878, but never attended college. Mary first saw the ocean in 1881 when she accompanied her brother, Richard Rathbun, to Woods Hole, Massachusetts. He was employed as a scientific assistant to Addison Emery Verrill, alongside Verrill's chief assistant, the carcinologist Sidney Irving Smith. Mary helped label, sort and record Smith's specimens, and worked on crustaceans ever since.

For three years, Mary worked on a voluntary basis for her brother, before being granted a clerkship by Spencer Fullerton Baird at the Smithsonian Institution. She continued to work at the museum, largely unaided, and after 28 years, she was promoted to assistant curator in charge of the Division of Crustacea. Her largest work was Les crabes d'eau douce ("Freshwater crabs"), published in three volumes in 1904–1906. She wrote or co-wrote 166 papers in total, including descriptions of 1147 new species and subspecies, 63 new genera, one subfamily, 3 families and a superfamily, as well as other nomenclatural novelties. The taxa first described by Rathbun include important commercial species such as the Atlantic blue crab Callinectes sapidus, and the tanner crab, Chionoecetes bairdi. She retired on the last day of 1914, but did not stop working until her death. She qualified for a Ph.D. at George Washington University in 1917.

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Credit: Gideon Pisanty

Ocypode cursor is a species of ghost crab that lives on sandy beaches in the Atlantic Ocean and Mediterranean Sea.

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General images

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

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