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 and Arcitalitrus sylvaticus.
Phronima is a genus of small, deep sea hyperiid amphipods of the family Phronimidae. It is found throughout the world's oceans, except in polar regions. Phronima species live in the pelagic zone of the deep ocean. Their bodies are semitransparent. Although commonly known as parasites, they are more technically correctly called parasitoids. Instead of constantly feeding on a live host, females attack salps, using their mouths and claws to eat the animal and hollow out its gelatinous shell. Phronima females then enter the barrel and lay their eggs inside, then propel the barrel through the water as the larvae develop, providing them with fresh food and water.
Thorina is a genus of amphipod crustaceans comprising the two species Thorina spinosa and Thorina elongata. They are deep-sea species, found at depths of 900 metres (3,000 ft) and 1,500–4,892 m (4,921–16,050 ft), respectively, in the North Atlantic Ocean and Arctic Ocean.
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.
Epimeriidae is a family of relatively large amphipods found in cold oceans around the world.
Phronima sedentaria is a species of amphipod crustaceans found in oceans at a depth of up to 1 km (0.6 mi). They are large in size relative to other members of the family Phronimidae. Individuals may be found inside barrel-like homes, created most commonly from the tunics of select species of pelagic tunicates; Phronima females appropriate these tunics and rear their young within. P. sedentaria is known to employ multiple feeding strategies and other interesting behaviors, including daily vertical migration. The species is also known by the more common names pram bug and barrel shrimp.
Amaryllididae is a family of marine benthic amphipods found throughout the southern hemisphere. These smooth, laterally compressed amphipods can be distinguished by the accessory setal row of the mandible having a distal tuft. It was first described in 2002 by James K. Lowry and Helen E. Stoddart. It contains the following genera:
Alicella gigantea is the largest species of amphipod ever observed, with some individuals reaching up to 34 centimetres (13 in) long. The average length of A. gigantea ranges from 72.5 to 141.0 millimeters, and its weight ranges from 4.2 to 45 grams. Comparatively to other amphipods, the A. gigantea grows at a much faster rate. Formerly included in the family Lysianassidae, a new family, Alicellidae, was erected in 2008 for Alicella and five related genera. The species lives only at great depths; the first specimens were collected at the end of the 19th century from the Madeira Abyssal Plain, and subsequent specimens have been found in other abyssal plains of both the Atlantic and Pacific Oceans, as well as from the Kermadec Trench in the southwest Pacific. One specimen was found in the stomach of a black-footed albatross, but is thought to have been dead before it was eaten.
Neolithodes is a genus of king crabs in the subfamily Lithodinae. They are found in all major oceans, both in high and low latitudes. Although there are records from water as shallow as 70 m (230 ft) in cold regions, most records are much deeper, typically 700–2,000 m (2,300–6,600 ft), with the deepest confirmed at 5,238 m (17,185 ft). They are fairly large to large crabs that typically are reddish in color and spiny, although the size of these spines varies depending on species.
Nototropis falcatus is a species of amphipod crustacean. It is whitish in colour, with brown patches, and grows to a total length of around 7 mm (0.3 in). It lives on soft sediment such as fine sand at depths of 10 to 50 metres, from northern Norway to the west coast of Ireland, including the North Sea, and as far south as the southern Bay of Biscay.
Alicellidae is a family of amphipod crustaceans, which live as scavengers in the deep sea, often in association with hydrothermal vents. The family includes the following genera:
Jassa marmorata is a species of tube-building amphipod. It is native to the northeast Atlantic Ocean but has been introduced into northeast Asia. J. marmorata are greyish in colour with reddish brown markings. The can grow to a length of up to 10 millimetres (0.39 in). They are generally found in fouling communities and intertidal areas where they build tubes of detritus and algae fragments using silky mucus secretions. They are remarkable for having two distinct morphs of males with two different mating strategies. The 'major' morphs are fighter males, while the 'minor' morphs are sneaker males.
Themisto is a genus of marine amphipods in the family Hyperiidae. Their distribution is cosmopolitan.
Luckia is a genus of amphipod crustaceans in the family Pontogeneiidae, with the sole species Luckia striki. It is found in hydrothermal vents in the Atlantic Ocean.
Pseudamphithoides incurvaria is a species of amphipod crustacean in the family Ampithoidae. It is native to shallow water in the tropical western Atlantic Ocean where it creates a home for itself from fragments of the algae on which it feeds. This seaweed contains certain chemicals that are distasteful and protect it from predatory fish.
Eurythenes is a genus of marine amphipods in the family Eurytheneidae.
Eurythenes plasticus is a species of amphipod of the genus Eurythenes, first described in 2020. It was named in reference to the PET plastic found in its stomach, after researchers wanted to highlight the impact of plastic pollution.
Eurythenes obesus is a species of amphipod of the genus Eurythenes. It was first described in 1905 by Édouard Chevreux.
Eurythenes atacamensis is a species of amphipod restricted to the Peru-Chile ocean trench.
Parawaldeckia is a genus of amphipod crustacean in the family, Lysianassidae. and was first described by Thomas Roscoe Rede Stebbing in 1910. The type species is Parawaldeckia thomsoni.
