barbel-like organ below the mouth. In true eels by contrast, the ventral fins are never well-developed and usually missing entirely. Cusk-eels have large mouths relative to their heads, with the upper jaw reaching beyond the eye, and paired nostrils on either side of the head. In cusk-eels, scales are potentially absent, and when present, they are small. Reproduction Unlike their close relatives, the viviparous brotulas of the family Bythitidae, cusk-eel species are egg-bearing, or oviparous, organisms. While the specifics of the eggs of the family Ophidiidae are unknown, they are believed to be either spawned as individual, free-floating eggs in the open water or are placed in a mucilaginous raft, which will float for several days until they hatch into cusk-eel larvae. These larvae live amongst the plankton relatively close to the water's surface and are believed to be able to control their metamorphosis into adult cusk-eels, allowing them to disperse over greater distances into less utilized habitats and reduce competition in concentrated areas. Conservation status While a few species are fished commercially – most notably the pink cusk-eel, Genypterus blacodes – and several species of the order Ophidiiformes are listed as vulnerable, not enough information has been gathered about Ophidiidae as a whole to determine their conservation status. Genera The cusk-eel family contains about 240 species, grouped into 50 genera:Subfamily Brotulinae Genus Brotula – typical brotulas Subfamily Brotulotaenilinae Genus Brotulotaenia Subfamily Neobythitinae Genus Abyssobrotula Genus Acanthonus – boney-eared assfish Genus Alcockia Genus Apagesoma Genus Barathrites Genus Barathrodemus Genus Bassogigas Genus Bassozetus Genus Bathyonus Genus Benthocometes Genus Dannevigia – Australian tusk Genus Dicrolene Genus Enchelybrotula Genus Epetriodus – needletooth cusk Genus Eretmichthys Genus Glyptophidium Genus Holcomycteronus Genus Homostolus – filament cusk Genus Hoplobrotula Genus Hypopleuron – whiptail cusk Genus Lamprogrammus Genus Leptobrotula Genus Leucicorus Genus Luciobrotula Genus Mastigopterus Genus Monomitopus Genus Neobythites Genus Neobythitoides Genus Penopus Genus Petrotyx Genus Porogadus Genus Pycnocraspedum Genus Selachophidium – Gunther's cusk-eel Genus Sirembo Genus Spectrunculus Genus Spottobrotula Genus Tauredophidium Genus Typhlonus Genus Ventichthys – East-Pacific ventbrotula Genus Xyelacyba Subfamily Ophidiinae Genus Cherublemma – black brotula Genus Chilara – spotted cusk-eel Genus Genypterus Genus Lepophidium Genus Menziesichthys Genus Ophidion Genus Otophidium Genus Parophidion Genus Raneya – banded cusk-eel Gallery References External links Taxa named by Constantine Samuel Rafinesque