The cusk-eel
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
, Ophidiidae, is a group of
marine bony fishes in the
Ophidiiformes
Ophidiiformes is an order of ray-finned fish that includes the cusk-eels (family Ophidiidae), pearlfishes (family Carapidae), viviparous brotulas (family Bythitidae), and others. Members of this order have small heads and long slender bodies. Th ...
order. The
scientific name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
is from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''ophis'' meaning "snake", and refers to their
eel
Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...
-like appearance. True eels, however, diverged from other
ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...
during the
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
, while cusk-eels are part of the
Percomorpha
Percomorpha () is a large clade of ray-finned fish that includes the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish.
Evolution
Percomorpha are the most diverse group of teleost fish today. Teleosts, an ...
clade, along with tuna, perch, seahorses, and others.
Distribution
Cusk-eels are found in temperate and tropical oceans throughout the world. They live close to the sea bottom, ranging from shallow water to the
hadal zone
The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around below sea level, and exists in long, narrow, topographic V-shaped depressions.
The cumula ...
. One species, ''
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. Alt ...
'', was recorded at the bottom of the
Puerto Rico trench
The Puerto Rico Trench is located on the boundary between the Caribbean Sea and the Atlantic Ocean. The oceanic trench, the deepest in the Atlantic, is associated with a complex transition between the Lesser Antilles subduction zone to the sou ...
, making it the deepest recorded fish at .
Ecology
Cusk-eels are generally very solitary in nature, but some species have been seen to associate themselves with tube worm communities.
Liking to be hidden when they are not foraging, they generally associate themselves within muddy bottoms, sinkholes, or larger structures that they can hide in or around, such as caves, coral crevices, or communities of bottom-dwelling invertebrates, with some parasitic species of cusk-eel actually living inside of
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
hosts, such as
oysters,
clams
Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two ...
, and
sea cucumbers
Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...
.
Cusk-eels generally feed
nocturnally, preying on invertebrates,
crustaceans
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
, and other small bottom-dwelling fishes.
Phylogeny
Due to the inconsistencies in specific morphological characteristics in closely related species, attempts to use different characters, such as the position of
pelvic fins
Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods.
Structure and function Structure
In actinopterygians, the pelvic fin consists of two e ...
, to classify Ophiididae into distinct families has proven highly unsatisfactory. Overall, Ophidiidae are classified based on whether or not they practice viviparity and the structures they contain that are associated with bearing life.
Characteristics
Cusk-eels are characterized by a long, slender body that is about 12-13 times as long as it is deep. The largest species, ''
Lamprogrammus shcherbachevi
''Lamprogrammus shcherbachevi'', the scaleline cusk, is a species of marine ray-finned fish in the family Ophidiidae.
Description
Attaining a maximum length of in males, this species is the largest among the cusk-eels. This species is character ...
'', grows up to in length, but most species are shorter than . Their dorsal and anal fins are typically continuous with the
caudal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
(with exception to a few species), forming a long, ribbon like fin around the posterior of the cusk-eel’s body.
This caudal fin will often be seen to be reduced to a fleshy or bony point, especially when confluent with the dorsal and anal fins. The
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...
to
anal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
ray ratio is approximately 1.5:1, leading to the dorsal fin typically being longer than the anal. The
pectoral fins
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...
of cusk-eels are typically longer than the length of their head. Unlike true
eel
Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...
s of the order
Anguilliformes
Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stag ...
, cusk-eels have
ventral fin
Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods.
Structure and function Structure
In actinopterygians, the pelvic fin consists of two ...
s that are developed into a forked
barbel Barbel may refer to:
*Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles
*Barbel (fish), a common name for certain species of fish
**''Barbus barbus'', a species of cyprinid ...
-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
Scale or scales may refer to:
Mathematics
* Scale (descriptive set theory), an object defined on a set of points
* Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original
* Scale factor, a number w ...
are potentially absent, and when present, they are small.
Reproduction
Unlike their close relatives, the
viviparous
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
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
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
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
The pink cusk-eel, ''Genypterus blacodes'', is a demersal species of cusk-eel found in the oceans around southern Australia, Chile, Brazil, and around New Zealand except the east coast of Northland, in depths of . Their length is up to , and ...
, ''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
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
:
Subfamily Brotulinae
* Genus ''
Brotula'' – typical brotulas
Subfamily Brotulotaenilinae
* Genus ''
Brotulotaenia''
Subfamily
Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
* Genus ''
Abyssobrotula''
* Genus ''
Acanthonus'' –
boney-eared assfish
* Genus ''
Alcockia
''Alcockia'' is a genus in the cusk-eel family. It contains only the single species ''Alcockia rostrata'', which is found in the Indian and western Pacific Oceans, at depths of from . This species grows to a length of SL. The generic name ''A ...
''
* Genus ''
Apagesoma''
* Genus ''
Barathrites
''Barathrites'' is a genus of cusk-eels found in deep waters of the northwest Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and a ...
''
* Genus ''
Barathrodemus''
* Genus ''
Bassogigas
''Bassogigas'' is a genus of cusk eel from the subfamily Neobythitinae, part of the family Ophidiidae. The generic name "''Bassogigas''" comes from a combination of two Latin
Latin (, or , ) is a classical language belonging to the Ita ...
''
* Genus ''
Bassozetus
''Bassozetus'' is a genus of cusk-eels found in Atlantic, Indian and Pacific Ocean.
Species
There are currently 13 recognized species in this genus:
* '' Bassozetus compressus'' ( Günther, 1878) (Abyssal assfish) Tomiyama, S., Takami, M. & Fuku ...
''
* Genus ''
Bathyonus''
* Genus ''
Benthocometes''
* Genus ''
Dannevigia'' – Australian tusk
* Genus ''
Dicrolene''
* Genus ''
Enchelybrotula
''Enchelybrotula'' is a genus of deep-water cusk-eels.
Species
There are currently two recognized species in this genus:
* ''Enchelybrotula gomoni'' Daniel Morris Cohen, Cohen, 1982
* ''Enchelybrotula paucidens'' Hugh McCormick Smith, H. M. Smit ...
''
* Genus ''
Epetriodus'' – needletooth cusk
* Genus ''
Eretmichthys''
* Genus ''
Glyptophidium
''Glyptophidium'' is a genus of cusk-eels.
Species
There are currently seven recognized species in this genus:
* ''Glyptophidium argenteum'' Alcock, 1889
* ''Glyptophidium effulgens'' J. G. Nielsen & Machida, 1988
* ''Glyptophidium japonicum' ...
''
* Genus ''
Holcomycteronus
''Holcomycteronus'' is a genus of cusk-eels. It includes '' Holcomycteronus profundissimus'', long thought to be the deepest-living fish in the world's oceans.
Species
There are currently six recognized species in this genus. Many were formerly ...
''
* Genus ''
Homostolus'' – filament cusk
* Genus ''
Hoplobrotula''
* Genus ''
Hypopleuron'' – whiptail cusk
* Genus ''
Lamprogrammus
''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, 1958 (Legless cuskeel)
* '' Lamprogra ...
''
* Genus ''
Leptobrotula''
* Genus ''
Leucicorus''
* Genus ''
Luciobrotula''
* Genus ''
Mastigopterus
''Mastigopterus imperator'' is a species of cusk-eel found in the Indian and Pacific Oceans where it occurs at depths of from . This species grows to a length of SL. It is the only known member of its genus
Genus ( plural genera ) is a ...
''
* Genus ''
Monomitopus''
* Genus ''
Neobythites''
* Genus ''
Neobythitoides''
* Genus ''
Penopus''
* Genus ''
Petrotyx''
* Genus ''
Porogadus''
* Genus ''
Pycnocraspedum''
* Genus ''
Selachophidium
The barbed brotula (''Selachophidium guentheri'') is a species of cusk-eel found in the Indian and Atlantic Oceans off of the southern coast of Africa where it is found at depths of from . This species grows to a length of TL. This species is ...
'' – Gunther's cusk-eel
* Genus ''
Sirembo''
* Genus ''
Spectrunculus
''Spectrunculus'' is a genus of cusk-eels found in the Atlantic and Pacific Oceans.
Species
There are currently two recognized species in this genus:
* ''Spectrunculus crassus'' ( Vaillant, 1888)
* ''Spectrunculus grandis
''Spectrunculus gran ...
''
* Genus ''
Spottobrotula
''Spottobrotula'' is a genus of cusk-eels.
Species
There are currently 3 recognized species in this genus:
* ''Spottobrotula mahodadi'' Daniel Morris Cohen, Cohen & Jørgen G. Nielsen, J. G. Nielsen, 1978
* ''Spottobrotula mossambica'' Jørgen G ...
''
* Genus ''
Tauredophidium
''Tauredophidium hextii'' is a species of cusk-eel found in the Indian and western Pacific Oceans. It occurs at depths of from . This species grows to a length of SL. It is the only known member of its genus. The specific name honours Rear- ...
''
* Genus ''
Typhlonus''
* Genus ''
Ventichthys'' – East-Pacific ventbrotula
* Genus ''
Xyelacyba''
Subfamily
Ophidiinae
Ophidiinae is a subfamily of the cusk eel family Ophidiidae. The species in the subfamily are characterised by having their pelvic fins situated far forward on the body and supported by a forward orientated extension of the pelvic girdle, they la ...
* Genus ''
Cherublemma
''Cherublemma emmelas'', the black brotula, is a species of cusk-eel found along the Pacific coast of Central and South America from Baja California to Chile. It occurs at depths of from . This species grows to a length of SL. It is the onl ...
'' – black brotula
* Genus ''
Chilara'' – spotted cusk-eel
* Genus ''
Genypterus
''Genypterus'' is a genus of cusk-eels.
Etymology
''Genypterus'' is derived from the Greek words ''genyos'' = face, jaw and ''pteron'' = wing, fin.
Species
There are currently five recognized species in this genus:
* ''Genypterus blacodes'' ( ...
''
* Genus ''
Lepophidium''
* Genus ''
Menziesichthys
''Menziesichthys'' is a genus of marine ray-finned fishes belonging to the family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The pur ...
''
* Genus ''
Ophidion''
* Genus ''
Otophidium
''Otophidium'' is a genus of cusk-eels, part of the subfamily Ophidiinae in the Family (biology), family Ophidiidae. They are found in the western Atlantic and eastern Pacific.
Species
There are currently four recognized species in this genus:
* ...
''
* Genus ''
Parophidion''
* Genus ''
Raneya'' – banded cusk-eel
Gallery
File:Brotula multibarbata.jpg, ''Brotula multibarbata
''Brotula barbata'', commonly known as the goatsbeard brotula, is a species of cusk-eel in the genus '' Brotula''. It lives in the Indo-Pacific, in depths of up to 300 meters. It is dark brown with a submarginal black band and narrow white borde ...
'' ( Brotulinae)
File:Bassozetus normalis.jpg, ' (Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
)
File:Lamprogrammus niger.jpg, ''Lamprogrammus niger
''Lamprogrammus niger'' is a species of fish in the 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 ...
'' (Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
)
File:Monomitopus agassizii.jpg, '' Monomitopus agassizii'' (Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
)
File:Porogadus miles.jpg, '' Porogadus miles'' (Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
)
File:Tauredophidium hextii.jpg, '' Tauredophidium hextii'' (Neobythitinae
Neobythitinae is a subfamily of cusk eel from the family Ophidiidae. They are mostly fishes of deeper waters, occurring from the continental shelf down to as deep as at the bottom of the Puerto Rico trench where the deepest known fish, '' Aby ...
)
File:Otophidium omostigma.jpg, ''Otophidium omostigma
The polka-dot cusk-eel (''Otophidium omostigma''), is a species of ray-finned fish found in the Western Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Ea ...
'' (Ophidiinae
Ophidiinae is a subfamily of the cusk eel family Ophidiidae. The species in the subfamily are characterised by having their pelvic fins situated far forward on the body and supported by a forward orientated extension of the pelvic girdle, they la ...
)
References
External links
{{Taxonbar, from=Q809481
Taxa named by Constantine Samuel Rafinesque