Opisthoproctidae
by D. M. Cohen
Mouth small, no teeth on maxillae and premaxillae, absent from dentary in most. Eyes tubular in most, many with an accessory 'eye' that resembles an orbital photophore. Inter-orbital very narrow. Rectal light organ present in some.
Oceanic, mesopelagic. Not generally common but some local centres of abundance. Pelagic eggs and larvae. Most often caught singly but occasionally in aggregations of 20 or more individuals. No commercial importance.
Genera 6; in Clofnam area 4.
Recent revisions: Cohen (1964).