Daphnia A genus of crustaceans belonging to the class Branchiopoda and order Cladocera (water fleas). Daphnia species have a transparent carapace and a protruding head with a pair of highly branched antennae for swimming and a single median compound eye. The five pairs of thoracic appendages form an efficient filter-feeding mechanism. Reproduction can take place without mating, i.e. by parthenogenesis. Some species exhibit cyclomorphosis.

Daphnia (water flea) See CLADOCERA; CYCLOMORPHOSIS.