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

Carcinus maenas (Malacostraca: Decapoda: Carcinidae)

Carcinus maenas, the shore crab or green crab, is a common littoral crab, and an important invasive species, listed among the 100 "world's worst alien invasive species". Although native to the Baltic Sea, North Sea and north-east Atlantic Ocean, it has since become established on both east and west coasts of North America, in Argentina, South Africa and Australia. C. maenas is a predator feeding on many organisms, particularly bivalve molluscs (such as clams, oysters, and mussels), polychaetes and small crustaceans. It is primarily nocturnal, although activity also depends on the tide, and crabs can be active at any time of day.

Did you know?

Pestarella tyrrhena (Decapoda: Callianassidae)

... that the mud shrimp Pestarella tyrrhena (pictured) has been used as bait by fishermen for over 200 years?
... that Squilla mantis is the only native stomatopod to be fished for on a commercial scale in the Mediterranean Sea?
... that the endangered Syncaris pacifica uses variable translucency and color changing crypsis for underwater camouflage?
... that the slipper lobster Scyllarus arctus is less common around Great Britain than the giant squid Architeuthis dux?

Selected biography

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.

Selected image

Pachygrapsus marmoratus (Decapoda: Grapsidae)

Pachygrapsus marmoratus is a species of crab which lives in the Black Sea, the Mediterranean Sea and parts of the Atlantic Ocean.

General images

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

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