Ophidiiformes is an order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of ray-finned fish that includes the cusk eels (family Ophidiidae
The cusk-eels family are a group of marine bony fishes in the order Ophidiiformes. The scientific name is from Greek ophis meaning "snake", and refers to their eel-like appearance...

), pearlfish
Pearlfish is a general name for a variety of marine fish species in the Carapidae family. Pearlfish have been found in tropical waters of the Atlantic, Indian, and Pacific Oceans at depths up to along oceanic shelves and slopes....

es (family Carapidae), brotula
Brotulas are a family, Bythitidae, of ophidiiform fishes, also known as viviparous brotulas as they bear live young. They are found in tropical and subtropical waters throughout the world...

s (family Bythitidae), and others.

This order includes a variety of deep-sea species, including the deepest known, Abyssobrotula galatheae
Abyssobrotula galatheae
Abyssobrotula galatheae is a species of cusk eel in the family Ophidiidae, and the only species in its genus. It is the deepest-living fish known; one specimen, trawled from a depth of 8,370 m in the Puerto Rico Trench in 1970, holds the record for the deepest fish ever captured...

, found at 8370 metres (27,460.6 ft) in the Puerto Rico Trench
Puerto Rico Trench
The Puerto Rico Trench is an oceanic trench located on the boundary between the Caribbean Sea and the Atlantic Ocean. The trench is associated with a complex transition between the subduction zone to the south along the Lesser Antilles island arc and the major transform fault zone or plate boundary...

. Many other species, however, live in shallow water, especially near coral reefs, while a few inhabit freshwater. Most species live in tropical or subtropical habitats, but some species are known from as far north as the coast of Greenland, and as far south as the Weddell Sea
Weddell Sea
The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha Coast, Queen Maud Land. To the east of Cape Norvegia is...


Ophidiiform fish typically have slender bodies with small heads, and either smooth scales, or none at all. They have long dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

s, and an anal fin that is typically united with the caudal fin. The group includes pelagic, benthic, and even parasitic species, although all have a similar body form. Some species are viviparous, giving birth to live young, rather than laying eggs. They range in size from Grammanoides opisthodon which measures just 5 centimetres (2 in) in length, to Lamprogrammus shcherbachevi at 2 metres (6.6 ft) in length.

The families Ranicipitidae (tadpole cod
Tadpole cod
The Tadpole cod is a deepwater fish found in the oceanic islands off New Zealand and in the mid South Atlantic at depths ranging from 1200 - 1600 m....

s) and Euclichthyidae (eucla cod
Eucla cod
The Eucla cod, Euclichthys polynemus, is a deepwater marine fish belonging to the cod order . It is the only species currently classified in the family Euclichthyidae. It is named after the town of Eucla, Western Australia, in whose coastal waters it is found.The Eucla cod has a long and tapering...

s) were formerly classified in this order, but are now preferred in Gadiformes
Gadiformes is an order of ray-finned fish, also called the Anacanthini, that includes the cod and its allies. Many major food fish are in this order. They are found in marine waters throughout the world, and there are also a small number of freshwater species.Common characteristics include the...

; Ranicipitidae has been absorbed within the family Gadidae
Gadidae is a family of marine fish, included in the order Gadiformes. It includes the cod, haddock, whiting, and pollock.Most species of gadid are found in temperate waters of the northern hemisphere, although there are some exceptions. They are generally medium sized fish, and are distinguished...

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