Isopoda is an order of crustacean, which includes woodlice and their relatives. Members of this group are called Isopods and include both terrestrial and aquatic species. 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.
Cymothoa exigua, or the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. It enters fish through the gills. The female attaches to the tongue, while the male attaches to the gill arches beneath and behind the female. Females are 8–29 mm (0.3–1.1 in) long and 4–14 mm (0.16–0.55 in) wide. Males are about 7.5–15 mm (0.3–0.6 in) long and 3–7 mm (0.12–0.28 in) wide. The parasite severs the blood vessels in the fish's tongue, causing the tongue to fall off. It then attaches itself to the remaining stub of tongue and the parasite itself effectively serves as the fish's new "tongue".
The blacktailed spurdog is a dogfish, a member of the family Squalidae, found around New Caledonia in the central Pacific Ocean, at depths from 320 to 320 m. Its length is up to 75 cm.
The geometric moray is a moray eel of the family Muraenidae found throughout the western Indian Ocean at depths to 40 m. Its length is up to 65 cm. It is parasitized by Ichthyoxenus puhi, a species of isopod.
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.
A woodlouse is any crustacean belonging to the suborder Oniscidea within the order Isopoda. They get their name from often being found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects.
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.
Aega psora is a species of isopod crustacean that parasitises a number of fish species in the North Atlantic. It is a serious ectoparasite of larger species of fish, particularly when they are injured.
Cymothoa elegans is a species of parasitic isopod in the genus Cymothoa. It has rarely been recorded, with all records coming from the north coast of Java. They are in the arthropod phylum and can more closely be classified as crustaceans.
Aega antarctica is a species of isopod crustacean. It is a temporary ectoparasite of fish, feeding on the fish's blood and then dropping to the seabed to digest its meal over a period of several months. It is found in the seas around Antarctica.
Uromunna sheltoni is a species of isopod first described by Brian Kensley in 1977. U. sheltoni is included in the genus Uromunna and family Munnidae. No subspecies are listed. The species was first collected by Peter Shelton of the University of Cape Town, for whom it is named.
Gastrosaccus spinifer is a shrimp-like crustacean in the order Mysida, the opossum shrimps, native to the eastern Atlantic Ocean and the coasts of Northern and Western Europe.
Prodajus ostendensis is a species of marine isopod in the family Dajidae and is found in the North Sea. It is an ectoparasite of the opossum shrimp Gastrosaccus spinifer. It is normally found living in the host's marsupium and devouring its eggs.
Anilocra pomacentri is a species of marine isopod in the family Cymothoidae. It is found off the coast of eastern Australia and is an external parasite of the yellowback puller, a species of damselfish. The presence of the parasite on a fish causes a significant slowing of the growth rate and an increased mortality.
Anilocra capensis is a species of parasitic isopod in the family Cymothoidae. It is endemic to southern Africa. The species preferentially attaches itself to the hottentot seabream.
Elthusa is a genus of isopods in the family Cymothoidae, with 40 described species.
Ceratothoa steindachneri is an ectoparasite known as a tongue biter. It parasitises fish by attaching to the tongue, causing atrophy. It then replaces the tongue.
Acrobelione halimedae is an isopoda parasite present in the waters off Singapore. First described in 2017, by Boyko, Williams & Shields.
Ceratothoa oestroides is a crustacean isopod, obligate ectoparasite of marine fish that dwells in the buccal cavity. It is the causative agent of various pathologies including tissue damage at the parasitisation site (tongue), growth defects, decrease in mean host weight and size and increases mortalities in farmed and wild fish populations. It has been recorded in six different fish families: Sparidae, Carangidae, Clupeidae, Maenidae, Scorpenidae, and Mugilidae.
Ceratothoais a genus of isopod ectoparasites of teleost fish, first described by James Dwight Dana in 1852. Infection by Ceratothoa can cause anaemia, lesions, growth retardation, emaciation, and mortality in their fish hosts.
