Portal:Crustaceans

Portal topics: Activities; Culture; Geography; Health; History; Mathematics; Nature; People; Philosophy; Religion; Society; Technology; Random portal

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...)

Refresh with new selections below (purge)

Selected article

Caprella mutica, commonly known as the Japanese skeleton shrimp, is a species of skeleton shrimp. It is a relatively large caprellids, reaching a maximum length of 50 mm (2.0 in). The species is sexually dimorphic, with the males usually being much larger than the females. It is characterised by their "hairy" first and second thoracic segments and the rows of spines on their bodies. Body colour ranges from green to red to blue, depending on the environment. It is an omnivorous, highly adaptable, opportunistic feeder. In turn, it provides a valuable food source for fish, crabs, and other larger predators. C. mutica is usually found in dense colonies attached to submerged man-made structures, floating seaweed, and other organisms.

C. mutica is native to shallow protected bodies of water in the Sea of Japan. In as little as 40 years, it has become an invasive species in the North Atlantic, North Pacific, and along the coasts of New Zealand. It is believed to have been accidentally introduced to these areas through the global maritime traffic and aquaculture. Outside of its native range, C. mutica is often exclusively synanthropic, being found in large numbers in and around areas of human activity. Its ecological and economic impact as an invasive species is unknown, but it poses a serious threat to native populations of skeleton shrimp in the affected areas.

Read more...

More selected articles

Did you know?

... that the crab Dyspanopeus sayi (pictured) may have lived in the Venetian Lagoon for 15 years before it was discovered?
... that the long-nosed spider crab, Libinia dubia, disguises itself by sticking bits of unpalatable seaweed and invertebrates on its carapace?
... that colour markings, considered rare among fossil crabs, have been found on Avitelmessus?
... that the sea anemone Calliactis tricolor is often attached to shells occupied by the hermit crabs Dardanus venosus and Clibanarius vittatus?

More Did you know facts

Selected biography

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.

Read more...

More selected biographies

Selected image

Credit: LiquidGhoul

Soldier crabs of the genus Mictyris, including M. longicarpus (pictured) congregate at low tide to feed by filtering mud. As the tide rises, they bury themselves, digging in a corkscrew pattern.

Read more...

More selected pictures

General images

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

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