Portal:Crustaceans

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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...)

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Krill is a shrimp-like marine invertebrate animal. These small crustaceans are important organisms of the zooplankton, particularly as food for baleen whales, manta rays, whale sharks, crabeater seals, other seals, and a few seabird species that feed almost exclusively on them. Krill occur in all oceans of the world. They are considered an important trophic connection – near the bottom of the food chain – because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antarctic krill, Euphausia superba, makes up an estimated biomass of over 500 million tonnes, roughly twice that of humans. Of this, over half is eaten by whales, seals, penguins, squid and fish each year, and is replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.

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Did you know?

... that the shrimp Periclimenes dardanicola lives on sea anemones on the shell of the hermit crab Dardanus pedunculatus (pictured), in one of the few associations between two decapods?
... that Canada's Federated Co-operatives partnered with SeaChoice to promote sustainable seafood, like the spiny lobster, through its co-operatives?
... that sponge crabs of the species Dromia dormia carry sponges on their back as camouflage, and have even used the sole of a shoe for that purpose?
... that the fairy shrimp Branchinecta gaini is the largest freshwater invertebrate in Antarctica?

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Charles Chilton (1860–1929) was a New Zealand zoologist, the first rector to be appointed in Australasia, and the first person to be awarded a D.Sc. degree in New Zealand.

Chilton was born on September 27, 1860 at Little Marstone, Pencombe (near Leominster, Herefordshire, England) but emigrated with his family to New Zealand in 1862. They settled on a farm at East Eyreton, North Canterbury. He was troubled by his hips from an early age, and had his left leg amputated, using an artificial leg and a crutch thereafter. In 1881, he gained an M.A. with first class honours from Canterbury College, having been taught by Frederick Wollaston Hutton, who inspired him to take up biology, especially the study of crustaceans, which had been little studied in New Zealand up to that time.

Chilton's first scientific publication followed that same year, when he described three new species of crustacean (two crabs and one isopod) from Lyttelton Harbour and Lake Pupuke. He surprised the scientific world later that year by describing four species of amphipod and isopod from groundwaters at the family farm in Eyreton. He went on to discover the isopod Phreatoicus typicus in the same location, the first example ever described of the suborder Phreatoicidea, the "earliest derived isopod[s]".

Charles Chilton became rector of Christchurch University College in 1921, the first time such a post had been granted in Australia or New Zealand. Chilton died on October 25, 1929 of a sudden attack of pneumonia, before he could collect his life's work into a single monograph. He had published 130 papers on crustaceans, mostly amphipods, isopods and decapods, from all around the world, but especially from New Zealand, subterranean and sub-Antarctic waters.

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Credit: Tom Page

Goose barnacles (order Pedunculata), such as these Lepas anatifera, are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the intertidal zone.

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General images

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

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