G.O. Sars, 1866
Diagnosis
Carapace up to 8 mm long (usually less than 1 mm). Ventral margin of carapace straight or concave at least in the oral region. Anterior rostral incisure always absent, antero-ventral incisure occasionally present. Valves usually strongly calcified, smooth or ornamented. Adductor muscle scars varied. Six or seven pairs of appendages. Antenna biramous; exopodite often reduced to a single scale or seta, endopodite generally with four podomeres and with stout terminal chelate setae. Maxilla usually with large branchial plate. Fifth limb with or without a branchial plate, either a maxilliped or a walking leg, or transformed (in males) into a clasping organ. Furca narrow, lamelliform bearing a few setae, or reduced, or absent.
Marine, brackish, freshwater and a few terrestrial. Mostly benthic, littoral and sub-littoral, some (particularly in freshwater) are planktonic; hence not keyed out here. With some 1600 species worldwide, this is the largest group of recent Ostracoda.
[Adapted from Angel, 2000]