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 stem-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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Did you know?

... that although the Pacific sand crab can only crawl and burrow backwards (pictured), it can also tread water?
... that Praunus flexuosus, the first mysid shrimp ever to be described, may have been transported to North America during World War II?
... that Calcinus tubularis is one of only two known species of hermit crab whose males and females inhabit different types of shell?
... that Petrolisthes eriomerus, when trying to escape from a predator, can cast off limbs as a diversion, with the claws of a cast limb still gripping vigorously after separation?

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Michèle de Saint Laurent (December 9, 1926 – July 11, 2003) was a French carcinologist. She was born on December 9, 1926 at Fontainebleau, near Paris. She studied general biology at the University of Paris under Pierre-Paul Grassé, earning her Diplôme de Licence in 1954. She started undertaking scientific research even before finishing her degree, and the resulting paper brought her into contact with staff at the Muséum national d'histoire naturelle in Paris. From 1955 until 1960, she worked at the Centre National de la Recherche Scientifique (CNRS), at their laboratory at Banyuls-sur-Mer; thereafter, she returned to the Paris museum.

The first major focus of Michèle de Saint Laurent's work was the systematics of hermit crabs. She also investigated other decapod crustaceans, particularly the Thalassinidea. As a result of this work, she was invited in 1974 to visit the Smithsonian Institution and was given an unidentified specimen which had been caught by the Albatross expedition in 1908. She and Jacques Forest realised that it represented a living relative of the Glypheoidea, a group previously thought to have been extinct since the Eocene. They described the new genus together in 1975, as Neoglyphea. De Saint Laurent's later work included a new classification of crabs (involving the recognition of a new section, Eubrachyura), and three new superfamilies (Axioidea, Enoplometopoidea and Retroplumoidea), as well as various works on the decapods of hydrothermal vents.

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Credit: Hans Hillewaert

Squilla mantis is a species of spearer mantis shrimp up to 20 cm (8 in) long, which is found and fished in the Mediterranean Sea.

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General images

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

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