The Cladocera are placed along with orders Conchostraca, Anacostraca and Notostraca in the class Branchiopoda (gill-feet), although the thoracic appendages of Cladocera are far fewer in number and generally more leg-like than in the other orders of this class.

Cladocerans are distinguished by a laterally flattened carapace that encloses the trunk and appendages but leaves the head protruding. The carapace is not hinged dorsally, as it is in the Conchostraca. The head may be small, and is often somewhat triangular in shape. There is, almost always, a pair of distinct compound eyes and these, again almost always, are preceded by a pair of single-celled eyes or ocelli.

The antennules are single-branched (uniramous) and carried somewhat ventrally. The antennae are two-branched, well-developed, and are the principal swimming organs. The trunk is free within the carapace. It comprises 4-5 segments with legs and terminates with a distinct furca.

Cladocerans inhabit most inland waters. A few are marine. Many species are parthenogenetic while some exhibit cyclomorphosis (seasonal change in morphology) and some develop different morphologies in the presence of different predators.

Mots cladocerans use the antennae for swimming, others crawl using the antennae or other appendages. Cladocerans are filter feeders and scrapers.

The Australian fauna comprises seven families: Sidiidae, Chydoridae, Macrothricidae, Moinidae, Bosminidae, Daphniidae and Ilyocryptidae.