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.
Corophiidae is a family of amphipods, containing the following genera:
Dogielinotidae is a family of amphipods. It is subdivided into three subfamilies, containing a total of twelve genera:
Haustoriidae is a family of amphipods. They are very distinctive stout-bodied burrowing animals.
Anisogammaridae is a family of small benthic amphipods, endemic to the northern part of the Pacific rim. The family contains the following genera:
Talitridae is a family of amphipods. Terrestrial species are often referred to as landhoppers and beach dwellers are called sandhoppers or sand fleas. The name sand flea is misleading, though, because these talitrid amphipods are not siphonapterans, do not bite people, and are not limited to sandy beaches.
Oedicerotidae is a family of amphipods. It comprises the following genera:
Lysianassidae is a family of marine amphipods, containing the following genera:
Allorchestes is a genus of amphipods with relatively small gnathopods, in the family Dogielinotidae; it contains the following species:
Orchestia is a genus of amphipods in the family Talitridae. Species in Orchestia are parasitized by the Filozoan species Txikispora philomaios.
Corophium is a genus of the amphipod family Corophiidae. Formerly a much larger genus, many species have been transferred to segregate genera such as Monocorophium and Crassicorophium.
Gammaridae is a family of amphipods. In North America they are included among the folk taxonomic category of "scuds", and otherwise gammarids is usually used as a common name.
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‰.
Crangonyctidae is a family of cave-dwelling freshwater amphipod crustaceans. It contains the following genera:
Hyalella is a genus of amphipods found in the Americas. They are mainly found in freshwater habitats.
Monocorophium is a genus of amphipod crustaceans.
Parorchestia is a genus of amphipods in the family Talitridae, containing the following species:
Parhyale is a genus of amphipod crustaceans, containing the following species:
Megalorchestia is a genus of sand-hoppers in the family Talitridae. The genus was erected by the German naturalist Johann Friedrich von Brandt in 1851 and the type species is Megalorchestia californiana.
Apohyale is a genus of amphipod in the family Hyalidae, first described by E.L. Bousfield and E.A. Hendrycks in 2002, The type species by original designation is Allorchestes pugettensis Dana, 1853, currently (2023) accepted as Apohyale pugettensis.
