Epicaridea is a former suborder of isopods, now treated as an infraorder in suborder Cymothoida. They are ectoparasites that inhabit other crustaceans, namely ostracods, copepods, barnacles and malacostracans. Epicarideans are found globally. Epicaridea are generally less well researched than other isopods.

There is a high degree of sexual dimorphism within epicarideans. The female is commonly very asymmetrical, often losing segmentation. Two pairs of rudimentary antennae are carried on the head. Mouthparts show little development, with only mandibles and maxillipeds present, sometimes with a second pair of rudimentary maxillae. Males are of smaller size than females and of different appearance. Development is through regressive metamorphosis, undergoing two or three larval stages.

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. Fossil epicaridean larvae are known from the Vendée amber of France and the Burmese amber of Myanmar, dating to the early Late Cretaceous, and also from Miocene aged Chiapas amber.

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