Giesbrecht, 1892
Females
R always present, with 2 filaments. Ce and Pd1, Pd4 and 5 separate, latter somite rounded or often with asymmetrical spiniform posterior corners. Ur usually of 3 somites, Gns often with asymmetrical spine armature; Ur2 may also bear processes. A1 24-25-segmented. A2 Exp and Enp almost equal in size; Coxa with 1 seta, Basis with 2 setae; Enp 2-segmented carrying 2 and 13-15 setae respectively; Exp 7-segmented carrying 1, 3, 1, 1, 1, 1, and 4 setae respectively, although further fusion of proximal segments may take place in some genera so that Exp is 5-segmented. Md gnathobase with well developed teeth, Basis with 4 setae, Enp 2-segmented with 3-4, and 6-8 setae respectively; Exp 4-segmented with 1, 1, 1, and 2-3 setae respectively. Mx1 variable, Li1 with 14-15 spines and setae, Li2 with 1-4 setae, Li3 with 2-4 setae, Li4 with 2-5 setae, Enp with 2-4 + 4-13 setae, Exp with 7-11 setae, Le2 with 1 small seta, Le1 with 8-9 setae, 2 of them short. Mx2 well-developed, Li1-5 with 4-5, 3, 3, 3, and 3-4 setae respectively, terminal part with 6-8 setae. Mxp relatively small, Coxa usually with 3 pronounced endites bearing 2, 3, and 3-4 setae respectively; Basis with 5 distal setae and sometimes with proximal row of inner-edge spinules, Enp 5-segmented with 2-4, 1-4, 1-3, 2-4 (1 usually on outer edge), and 3-4 setae respectively. P1-5 Exp and Enp 3-segmented; apical spine of Exp strongly serrate; sometimes Enp segments 1 and 2 fused.
Spine and seta formula: Spine and seta Centropagidae.
P5 biramous, natatory, Coxa and Basis without setae, Exp segments 1 and 2 with or without 1 outer edge spine, segment 2 with strong inner spine-like process, Exp segment 3 with or without 2 outer edge spines, 1 terminal serrate spine and 2 or 4 inner edge setae; Enp segments 1 and 2 with 0-1, 1 inner edge seta respectively, Enp segment 3 with 4-6 setae.
Males
Mouthparts and P1-4 identical to female apart from male A1, and sometimes P2. Ur of 4-5 somites. A1 prehensile on right. P5 asymmetrical, usually resembling other swimming legs, rami 2 or 3-segmented, right Exp variously transformed into grasping organ, sometimes Enp atrophied.
There are a number of genera in this family many of which live in freshwater.
Genus Centropages Kroyer, 1848 lives in marine habitats,.
Genus Gippslandia Bayly and Arnott, 1969 lives in estuarine environments in south-eastern Australia.
Genus Gladioferens Henry, 1919 lives in brackish, nearshore habitats in Australia and New Zealand.
Genus Isias Boeck, 1864 lives in nearshore marine habitats and is possibly benthopelagic.
Genus Parathalassius Dussart, 1986 lives in brackish water near the mouth of the La Foa River, New Caledonia. Genus Sinocalanus Burckhardt, 1913 and
Genus Limnocalanus Sars, 1863 live in northern hemisphere brackish and freshwater habitats.
The remaining genera are found in freshwater habitats.
Only the genus Centropages has been taken in the South Atlantic.