[1][2] They are ectoparasites that inhabit other crustaceans, namely ostracods, copepods, barnacles and malacostracans.

Mouthparts show little development, with only mandibles and maxillipeds present, sometimes with a second pair of rudimentary maxillae.

Development is through regressive metamorphosis, undergoing two or three larval stages.

[4] The oldest trace fossils of epicarideans, comprising preserved damage to gills of fossilised crustaceans, goes back to the Late Jurassic, and a lost specimen from the Toarcian of Western New Guinea suggests that it may go back further to the Early Jurassic.

[7] Eleven families are currently recognised within the suborder Epicaridea, divided into two superfamilies.