Cladocera

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Cladocera (water fleas; class Branchiopoda, order Diplostraca) Suborder of branchiopods in which the carapace encloses the trunk but not the head. The strongly biramous second antennae are the sole means of a rather jerky locomotion, the trunk appendages being reduced to five or six pairs, at least some of which bear food-filtering setae. The post-abdomen is bent ventrally and forward, and bears claws and spines modified for cleaning the carapace. Many cladocerans undergo cyclomorphosis. Cladocera are important food for many freshwater invertebrates and fish, and one genus, Daphnia, is sold commercially as food for aquarium fish. There are 425 species.