Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from 1 to 340 millimetres and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far described. They are mostly marine animals, but are found in almost all aquatic environments. Some 1,900 species live in fresh water, and the order also includes the terrestrial sandhoppers such as Talitrus saltator.
Gammaridea is one of the suborders of the order Amphipoda, comprising small, shrimp-like crustaceans. Until recently, in a traditional classification, it encompassed about 7,275 (92%) of the 7,900 species of amphipods described by then, in approximately 1,000 genera, divided among around 125 families. That concept of Gammaridea included almost all freshwater amphipods, while most of the members still were marine.
Ingolfiellidea is a small suborder of amphipods with only two families, Ingolfiellidae and Metaingolfiellidae. They are small, vermiform (worm-like) animals that live "in the soft mud of the deep-sea floor, as well as in high mountain freshwater river beds, or in subterranean fresh, brackish and marine interstitial waters of continental ground waters and continental shelves". Over 30 species are known from two families.
Anisogammaridae is a family of small benthic amphipods, endemic to the northern part of the Pacific rim. The family contains the following genera:
Chiltonia is a genus of amphipod crustaceans endemic to New Zealand. Four species are known, three of which live in fresh waters. They were first discovered by Charles Chilton in 1898 and the genus Chiltonia was erected the following year by T. R. R. Stebbing in Chilton's honour.
Paracrangonyx is a genus of amphipods in the family Paracrangonyctidae, comprising two species, Paracrangonyx compactus and Paracrangonyz winterbourni.
Phreatogammarus is a genus of amphipod crustaceans that are endemic to New Zealand. It is the only genus in the family Phreatogammaridae, and contains four species, three of which were described by Charles Chilton.
Gammarus roeseli is a species of freshwater amphipod native to Europe.
Gammarus acherondytes, the Illinois cave amphipod, is a species of crustacean in the family Gammaridae. The crustacean is endemic to the Illinois Sinkhole Plain of Monroe County and St. Clair County, in southwestern Illinois, including Illinois Caverns State Natural Area.
Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most species-rich genera of crustaceans. Different species have different optimal conditions, particularly in terms of salinity, and different tolerances; Gammarus pulex, for instance, is a purely freshwater species, while Gammarus locusta is estuarine, only living where the salinity is greater than 25‰.
Gammarus hyalelloides is a species of amphipod crustacean in the family Gammaridae. It is endemic to four springs in Jeff Davis County and Reeves County, Texas, and is listed as a vulnerable species on the IUCN Red List.
Niphargus is by far the largest genus of its family, the Niphargidae, and the largest of all freshwater amphipod genera.
Niphargidae is a family of amphipod crustaceans. Its distribution is in western Eurasia, and its members mainly live in subterranean freshwaters habitats. It contains the following genera:
Niphargus tatrensis is a troglobitic species of crustacean in the family Niphargidae, living in the karst waters of Austria, the Czech Republic, Hungary, Poland, and Slovakia. It can be found in caves, and also in karst springs and in wells in the karstic areas.
Caprella mutica, commonly known as the Japanese skeleton shrimp, is a species of skeleton shrimp. They are relatively large caprellids, reaching a maximum length of 50 mm (2.0 in). They are sexually dimorphic, with the males usually being much larger than the females. They are characterized by their "hairy" first and second thoracic segments and the rows of spines on their bodies. Body color ranges from green to red to blue, depending on the environment. They are omnivorous highly adaptable opportunistic feeders. In turn, they provide a valuable food source for fish, crabs, and other larger predators. They are usually found in dense colonies attached to submerged man-made structures, floating seaweed, and other organisms.
Gammarus baysali is a cave-dwelling species of freshwater amphipod crustacean, found in Turkey. The species belongs to the broader Gammarus pulex group and was scientifically described in 2013 from Cumayanı Cave, Zonguldak Province.
Caprella unica is a species of skeleton shrimp in the genus Caprella within the family Caprellidae. The larvae are plankton-like. They are relatively small, with two large and two small antennae. They only live in the sea, and are widely found in Cape Cod, Maine and Newfoundland.
Iphigenellidae is a freshwater family of amphipods in the superfamily Gammaroidea. It is found in the Ponto-Caspian region, which encompasses the Black, Azov, and Caspian Seas.
Niphargellus glenniei, also known as the south-western groundwater shrimp, is a species of amphipod from within the family Niphargidae. A native of the United Kingdom, it has been placed in the UK Biodiversity Action Plan list of priority species. It is the first aquatic troglobite to be given a conservation status within the UK.
Gammarus fossarum is a species complex of freshwater amphipod crustacean native to Europe. They are abundant members of the macroinvertebrate community, and also used as model organisms for ecotoxicology.
