Isopoda is an order of crustaceans. Members of this group are called isopods and include both aquatic species, and terrestrial species such as woodlice. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax called the marsupium.
The Gnathiidae are a family of isopod crustaceans. They occur in a wide range of depths, from the littoral zone to the deep sea. The adults are associated with sponges and may not feed. The juvenile form is known as a 'praniza', and it is a temporary parasite of marine fish. These forms are not larvae; Gnathiidae instead become parasitic during the manca stage. Mancae of the Gnathiidae closely resemble the adult form, however they lack the final pair of pereiopods.
Sphaeromatidae is a family of isopods, often encountered on rocky shores and in shelf waters in temperate zones. The family includes almost 100 genera and 619 known marine species. Within these genera, there are groups that share distinctive morphologies; further research may reclassify these genus-groups as separate families.
Onchotelson is a genus of isopod crustaceans in the family Phreatoicidae, which is endemic to Tasmania. It contains two species, both of which are listed as vulnerable on the IUCN Red List:
Uramphisopus is a monotypic genus of isopod crustaceans in the family Phreatoicidae. The only species is Uramphisopus pearsoni. It is only found in Brandum Bay basin in the north of Great Lake, Tasmania.
The Cymothoidae are a family of isopods in the suborder Cymothoida found in both marine and freshwater environments. Cymoithoids are ectoparasites, usually of fish, and they include the bizarre "tongue-biter", which attaches to a fish's tongue, causing it to atrophy, and replaces the tongue with its own body. Ceratothoa oestroides is one of the most devastating ectoparasites in Mediterranean aquaculture. Around 40 genera and more than 380 species of cymothoid are recognised. Species of the Cymothoidae are generally found in warmer waters and rarely in the cool and cold climates.
Nichollsia is a genus of isopod crustaceans from India. It comprises two species:
Anthuroidea is a superfamily of isopod crustaceans, formerly treated as a suborder, Anthuridea. The group is characterised by "an elongate cylindrical body form, without dorsal coxal plates, and with a uropodal exopod attached to the peduncle proximally and dorsally". There are more than 500 described species in 57 genera, arranged across six families:
Woodlice are terrestrial isopods in the suborder Oniscidea. Their name is derived from being often found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects.
A giant isopod is any of the almost 20 species of large isopods in the genus Bathynomus. They are abundant in the cold, deep waters of the Atlantic, Pacific, and Indian Oceans. Bathynomus giganteus, the species upon which the generitype is based, is often considered the largest isopod in the world, though other comparably poorly known species of Bathynomus may reach a similar size. The giant isopods are noted for their resemblance to the much smaller common woodlouse, to which they are related.
Asellota is a suborder of isopod crustaceans found in marine and freshwater environments. Roughly one-quarter of all marine isopods belong to this suborder. Members of this suborder are readily distinguished from other isopods by their complex copulatory apparatus. Other characteristics include six-jointed antennal peduncle, the styliform uropods, the fusion of pleonites 5, 4 and sometimes 3 to the pleotelson, and absence of the first pleopod in females.
Archaeoniscus is a genus of prehistoric isopods that first appeared during the Bajocian stage of the Middle Jurassic. It is a widespread genus with a paleogeographic distribution encompassing the continental margin environments of the central Atlantic Ocean and the western Tethys Ocean. Fossils of Archaeoniscus suggest that this genus lived in diverse aquatic habitats, including the marine, paralic, and freshwater environments. While earlier descriptions suggested that it may have had an ectoparasitic association with fishes, some researchers argue that at least two species, A. aranguthyorum and A. coreaensis, lived a benthic free-living lifestyle based on morphological characteristics that are either unsuitable for or unrelated to parasitic behavior.
The Microcerberidea are a suborder of isopod crustaceans. They are less than 2 mm (0.079 in) long, and live interstitially. They may be found in the eastern Pacific Ocean, and around the coasts of South America, Africa, the Mediterranean Sea, and India.
Phreatoicidae is a family of blind, freshwater isopods. They have survived apparently unchanged for 350 million years, and are only found in South Africa, India, Australia and New Zealand. They were first found near Christchurch in 1882 by Charles Chilton. The family Phreatoicidae now contains 13 genera:
Cymothoida is a suborder of isopod crustaceans with a mostly carnivorous or parasitic lifestyle. It contains more than 2,700 described species in four superfamilies. Members of the suborder are characterised by their specialised mouthparts which include a mandible with a tooth-like process which is adapted for cutting or slicing.
The Chaetiliidae are a family of isopod crustaceans in the suborder Valvifera, comprising these genera:
The Arcturidae are a family of marine isopod crustaceans in the suborder Valvifera. Members of the family resemble woodlice and are found globally in cooler areas in shallow seas.
Glyptonotus antarcticus is a benthic marine isopod crustacean in the suborder Valvifera. This relatively large isopod is found in the Southern Ocean around Antarctica. It was first described by James Eights in 1852 and the type locality is the South Shetland Islands.
Deto is a genus of woodlice in the family Detonidae. Members of this genus can be found along the coasts in areas of New Zealand, Namibia, South Africa and Australia.
Scutuloidea maculata is a species of marine isopods in the family Sphaeromatidae, first described by Charles Chilton in 1883. No subspecies are listed in the Catalogue of Life.
