An order of fresh-water branchiopod crustaceans, formerly included in the Cladocera. Exceptionally these organisms may be as much as 6 mm (0.24 in.) in length, but often are less than 1 mm (0.04 in.). So-called water fleas of the genus Daphnia are the most familiar anomopods. Daphnia and its close relatives swim freely in open water; however, many anomopods are benthic, predominantly crawling species.