Ophidiiformes is an

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

that includes the

cusk-eel The cusk-eel family, Ophidiidae, is a group of marine bony fishes in the Ophidiiformes order. The scientific name is from the Greek ''ophis'' meaning "snake", and refers to their eel-like appearance. True eels diverged from other ray-finned fi ...

s (family

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

pearlfish Pearlfish are marine fish in the ray-finned fish family Carapidae. Pearlfishes inhabit the tropical waters of the Atlantic, Indian, and Pacific Oceans at depths to , along oceanic shelves and slopes. They are slender, elongated fish with no s ...

es (family

Carapidae Pearlfish are marine fish in the ray-finned fish family Carapidae. Pearlfishes inhabit the tropical waters of the Atlantic, Indian, and Pacific Oceans at depths to , along oceanic shelves and slopes. They are slender, elongated fish with no s ...

viviparous brotula The viviparous brotulas form a family, the Bythitidae, of ophidiiform fishes. They are known as viviparous brotulas as they generally bear live young, although there are indications that some species (at least '' Didymothallus criniceps'') do n ...

s (family

Bythitidae The viviparous brotulas form a family, the Bythitidae, of ophidiiform fishes. They are known as viviparous brotulas as they generally bear live young, although there are indications that some species (at least '' Didymothallus criniceps'') do n ...

), and others. Members of this order have small heads and long slender bodies. They have either smooth scales or no scales, a long dorsal fin and an anal fin that typically runs into the caudal fin. They mostly come from the tropics and subtropics, and live in both freshwater and marine habitats, including abyssal depths. They have adopted a range of feeding methods and lifestyles, including

parasitism Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

. The majority are

egg-laying Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings known as ...

, but some are

viviparous In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juve ...

. The earliest fossil members are known from the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

, and include the basal ophidiiform '' Pastorius'' from

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

and several species of the basal cusk-eel ''

Ampheristus ''Ampheristus'' is an extinct genus of prehistoric marine ray-finned fish. It was a basal or stem member of the family Ophidiidae, which contains modern cusk-eels. Fossils are known from worldwide (the United States, Europe, India, and New Zeal ...

'' from the United States and Germany.

Distribution

This order includes a variety of deep-sea species, including the deepest known, ''

Abyssobrotula galatheae ''Abyssobrotula galatheae'' is a species of cusk eel in the family Ophidiidae. It is the deepest-living fish known; one specimen, trawled from a depth of in the Puerto Rico Trench in 1970, holds the record for the deepest fish ever captured. A ...

'', found at in the

Puerto Rico Trench The Puerto Rico Trench is located on the boundary between the North Atlantic Ocean and Caribbean Sea, parallel to and north of Puerto Rico, where the oceanic trench reaches the deepest points in the Atlantic Ocean. The trench is associated with ...

. 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 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 C ...

Characteristics

Ophidiiform fish typically have slender bodies with small heads, and either smooth scales, or none at all. They have long

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s, and an

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

that is typically united with the

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

. The group includes

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

, and even

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

species, although all have a similar body form. Some species are

, giving birth to live young, rather than laying eggs. They range in size from '' Grammanoides opisthodon'' which measures just in length, to ''

Lamprogrammus shcherbachevi ''Lamprogrammus'' is a genus of cusk-eels. Species There are currently five recognized species in this genus: * '' Lamprogrammus brunswigi'' ( A. B. Brauer, 1906) * '' Lamprogrammus exutus'' Nybelin & Poll Poll, polled, or polling may refer t ...

'' at in length. The families

Ranicipitidae ''Raniceps raninus'', the tadpole fish, is a species of Gadidae fish native to the northeast Atlantic Ocean around the coasts of France, Ireland, and the United Kingdom and the North Sea. This species grows to a total length of . It is of no im ...

( tadpole cods) and

Euclichthyidae The Eucla cod (''Euclichthys polynemus'') is a deepwater marine fish belonging to the cod order (Gadiformes). It is the only species currently classified in the family Euclichthyidae. It is named after the town of Eucla, Western Australia, in wh ...

( eucla cods) were formerly classified in this order, but are now preferred in

Gadiformes Gadiformes , also called the Anacanthini, are an order of ray-finned fish that include the cod, hakes, pollock, haddock, burbot, rocklings and moras, many of which are food fish of major commercial value. They are mostly marine fish found thr ...

; Ranicipitidae has been absorbed within the family

Gadidae The Gadidae are a family of marine fish, included in the order Gadiformes, known as the cods, codfishes, or true cods. It contains several commercially important fishes, including the cod, haddock, whiting, and pollock. Most gadid species ar ...

Classification

The order Ophidiiformes is subdivided into suborders and families as follows: * Order Ophidiiformes ** Genus †'' Pastorius'' (Late Cretaceous of Italy) ** Suborder Ophidioidei *** Family Acanthonidae Wong & Chen, 2024 (deepsea cusk-eels) *** Family Brotulidae Swainson, 1838 (bearded cusk-eels) *** Family

Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...

, 1810 (cusk-eels) *** Family

Poey, 1867 (pearlfishes) **Suborder Bythitoidei *** Family

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1861 — viviparous brotulas *** Family

Parabrotulidae The Parabrotulidae, the false brotulas, are a small family of bathypelagic cusk eels that currently contains two genera. The species in this family are known from the northwest Pacific Ocean and the northeast Atlantic Ocean The Atlantic ...

Nielsen, 1968 — false brotulas Until recent taxonomic revisions, the suborder Ophidioidei was a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

grouping. However, the Bythitoidei are

and seem to make up a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

, while the Ophidioidei are

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

Timeline of genera

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-65.5 till:15 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:5 start:-65.5 ScaleMinor = unit:year increment:1 start:-65.5 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:cenozoic value:rgb(0.54,0.54,0.258) id:paleogene value:rgb(0.99,0.6,0.32) id:paleocene value:rgb(0.99,0.65,0.37) id:eocene value:rgb(0.99,0.71,0.42) id:oligocene value:rgb(0.99,0.75,0.48) id:neogene value:rgb(0.999999,0.9,0.1) id:miocene value:rgb(0.999999,0.999999,0) id:pliocene value:rgb(0.97,0.98,0.68) id:quaternary value:rgb(0.98,0.98,0.5) id:pleistocene value:rgb(0.999999,0.95,0.68) id:holocene value:rgb(0.999,0.95,0.88) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:NAM7 bar:NAM8 bar:NAM9 bar:NAM10 bar:NAM11 bar:NAM12 bar:NAM13 bar:NAM14 bar:NAM15 bar:NAM16 bar:NAM17 bar:NAM18 bar:NAM19 bar:NAM20 bar:NAM21 bar:NAM22 bar:NAM23 bar:NAM24 bar:NAM25 bar:NAM26 bar:NAM27 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -65.5 till: -55.8 color:paleocene text:

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

from: -55.8 till: -33.9 color:eocene text:

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

from: -33.9 till: -23.03 color:oligocene text:

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

from: -23.03 till: -5.332 color:miocene text:

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text:

Pleist. The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

from: -0.0117 till: 0 color:holocene text: H. bar:eratop from: -65.5 till: -23.03 color:paleogene text:

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

from: -23.03 till: -2.588 color:neogene text:

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

from: -2.588 till: 0 color:quaternary text: Q. PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:paleocene bar:NAM1 from: -65.5 till: -61.7 text:

Eolamprogrammus ''Eolamprogrammus'' ("dawn '' Lamprogrammus''") is an extinct genus of prehistoric marine cusk-eel that lived during the earliest Eocene. It contains a single species, ''E. senectus'' from the earliest Ypresian-aged Danata Formation of Turkmenist ...

color:paleocene bar:NAM2 from: -65.5 till: -33.9 text:

color:eocene bar:NAM3 from: -55.8 till: 0 text: Ophidion color:eocene bar:NAM4 from: -55.8 till: 0 text:

Onuxodon ''Onuxodon'' is an Indo-Pacific genus of pearlfishes from the family Carapidae. The generic name is derived from the Greek ''onyx'' meaning "claw" and ''odon'' meaning "tooth", referring to the sharp fang like teeth of ''Onuxodon parvibrachium ...

color:eocene bar:NAM5 from: -55.8 till: 0 text: Oligopus color:eocene bar:NAM6 from: -55.8 till: 0 text: Ogilbia color:eocene bar:NAM7 from: -55.8 till: 0 text: Glyptophidium color:eocene bar:NAM8 from: -55.8 till: 0 text: Brotula color:eocene bar:NAM9 from: -48.6 till: -15.97 text: Nolfophidion color:eocene bar:NAM10 from: -48.6 till: 0 text:

Neobythites ''Neobythites'' is a genus of cusk-eels. Species These are the currently recognized species in this genus: * '' Neobythites alcocki'' J. G. Nielsen, 2002 * '' Neobythites analis'' Barnard, 1927 (Black-edged cusk-eel) * '' Neobythites andamanens ...

color:eocene bar:NAM11 from: -48.6 till: 0 text: Monomitopus color:eocene bar:NAM12 from: -48.6 till: 0 text: Hoplobrotula color:eocene bar:NAM13 from: -48.6 till: 0 text: Dannevigia color:eocene bar:NAM14 from: -48.6 till: 0 text:

Carapus ''Carapus'' is a genus of pearlfishes, with these currently recognized species: The ''Carapus'' (or pearlfish) belongs to the Carapidae family and are described as eel-like fishes. This particular organism is considered parasitic because it live ...

color:eocene bar:NAM15 from: -48.6 till: 0 text: Benthocomectes color:eocene bar:NAM16 from: -37.2 till: 0 text: Saccogaster color:eocene bar:NAM17 from: -37.2 till: 0 text:

Dipulus ''Dipulus'' is a genus of viviparous brotulas. Species There are currently four recognized species in this genus: * ''Dipulus caecus'' Edgar Ravenswood Waite, Waite, 1905 (Orange eelpout) * ''Dipulus hutchinsi'' Peter Rask Møller, Møller & We ...

color:oligocene bar:NAM18 from: -33.9 till: -28.4 text: Protobrotula color:oligocene bar:NAM19 from: -33.9 till: -28.4 text:

Propteridium ''Propteridium'' is an extinct genus of prehistoric bony fish that lived during the early Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 ...

color:oligocene bar:NAM20 from: -33.9 till: 0 text: Genypterus color:oligocene bar:NAM21 from: -33.9 till: 0 text: Diplacanthopoma color:oligocene bar:NAM22 from: -28.4 till: 0 text: Sirembo color:oligocene bar:NAM23 from: -28.4 till: 0 text: Echiodon color:miocene bar:NAM24 from: -23.03 till: 0 text: Lepophidium color:miocene bar:NAM25 from: -15.97 till: 0 text:

Dermatopsis ''Dermatopsis'' is a genus of viviparous brotulas. Species There are currently four recognized species in this genus: * '' Dermatopsis greenfieldi'' Møller & Schwarzhans, 2006 (Greenfield's mudbrotula) * '' Dermatopsis hoesei'' Møller & Schw ...

color:miocene bar:NAM26 from: -11.608 till: 0 text: Bassozetus color:pliocene bar:NAM27 from: -5.332 till: 0 text: Chilara PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -65.5 till: -55.8 color:paleocene text:

from: -55.8 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

from: -23.03 till: -5.332 color:miocene text:

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text:

from: -0.0117 till: 0 color:holocene text: H. bar:era from: -65.5 till: -23.03 color:paleogene text:

from: -23.03 till: -2.588 color:neogene text:

from: -2.588 till: 0 color:quaternary text: Q.

References

* * * {{Authority control Ray-finned fish orders Taxa named by Lev Berg