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Portal:Crustaceans

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The Crustaceans Portal

Abludomelita obtusata, an amphipod
Abludomelita obtusata, an amphipod

Crustaceans (from Latin word "crustacea" meaning: "those with shells" or "crusted ones") are mandibulate arthropods that are traditionally a part of the paraphyletic subphylum Crustacea (/krəˈstʃə/). Crustaceans are mainly aquatic, including decapods (shrimps, prawns, crabs, lobsters, and crayfish), seed shrimps, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. It is now well accepted that hexapods (insects and entognathans) are cladistically crustaceans, with the two groups now combined in the monophyletic clade Pancrustacea. The three classes Cephalocarida, Branchiopoda, and Remipedia are more closely related to the hexapods than they are to any 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

Homarus gammarus (Malacostraca: Decapoda: Nephropidae)
Homarus gammarus, known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, H. americanus. It may grow to a length of 60 cm (24 in) and a mass of 6 kilograms (13 lb), and bears a conspicuous pair of claws. In life, the lobsters are blue, only becoming "lobster red" on cooking. Mating occurs in the summer, producing eggs which are carried by the females for up to a year before hatching into planktonic larvae. Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots, mostly around the British Isles.

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Chionoecetes bairdi (Decapoda: Oregoniidae)
Chionoecetes bairdi (Decapoda: Oregoniidae)

Selected biography

William Elford Leach FRS (February 2, 1790 – August 26, 1836) was an English zoologist and marine biologist. In 1813, Leach was employed as assistant librarian in the Zoological Department at the British Museum. He set himself to sorting out the collections, many of which had been neglected since they had been left to the museum by Hans Sloane. During his time there he was made assistant keeper of the natural history department and became an expert on crustaceans and molluscs. In 1817, he was elected a fellow of the Royal Society. Leach also worked and published on insects, myriapods, arachnids, mammals and birds. Leach's nomenclature was a little eccentric - he named twenty-seven species after his friend John Cranch, who had collected the species in Africa and later died on HMS Congo. In 1818, he named nine genera after Caroline or anagrams of that name, possibly after his mistress. In 1821, he suffered a nervous breakdown due to overwork, and he resigned from the museum in March 1822. His elder sister took him to continental Europe to convalesce, and they travelled through France, Italy and Greece. He died of cholera in the Palazzo San Sebastiano, near Tortona, north of Genoa.

Selected image

Periclimenes imperator (Decapoda: Palaemonidae)
Periclimenes imperator (Decapoda: Palaemonidae)
Credit: Nick Hobgood

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.

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