See also pages Cl. 12 and Cl. 13 for more about cladoceran morpholigy and classification. According to Fryer's (1987a, b) classification system, the class Branchiopoda consists of 10 orders, of which 4 orders comprise the so-called Cladocera:
Marine cladocerans include 1 ctenopod and 7 onychopod species.
The diagnostic features of these new orders are described in detail by Fryer (1987b). Only the external features of Ctenopoda and Onychopoda, as defined by Fryer (1987b), are summarized below.