Diagnosis
Carapace shape and size very variable, usually with weak sexual dimorphism. In most genera the posterior edge of the carapace is straight and not indented to form a siphon when the valves are shut together. There is marked sexual dimorphism of the first antenna. In females there are 8 segments, although some may be fused together. In males the setae tend to longer and some carry suctorial discs. The sencond antenna tends to be more powerfully developed in males, but otherwise the exopodite is similar between the sexes. The endopodite of male of many species are developed into three-jointed clasping organs. The other limbs vary in their structure between the species and show little sexual dimorphism. The seventh limb is fitted with a terminal comb and a few to very many cleaning bristles. The intromittent organ is oval, highly muscular and placed more or less symmetrically close to the caudal furca. The caudal furca is developed into a wide range of forms but tends to be consistent within genera. The numbers of pairs claw setae also vary between genera. The upper lip is large and helmet-shaped and carries the opening of numerous glands. In many species some of these glands release luminescent secretions.
Remarks
The majority of cyprinid species belong to this sub-family, including the two planktonic oceanic genera, Gigantocypris and Macrocypridina, which are widespread and nearly ubiquitous at mesopelagic and greater depths.