Macrouridae is a

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 ...

of deep sea fish, a diverse and ecologically important group, which are part of the order of

cod Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...

-like fish, the

Gadiformes Gadiformes are an order of ray-finned fish, also called the Anacanthini, that includes the cod. Many major food fish are in this order. They are found in marine waters throughout the world and the vast majority of the species are found in tempe ...

. The species in the Macrouridae are characterised by their large heads which normally have a single barbel on the chin, projecting snouts, and slender bodies that taper to whip-like tails, without an obvious

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 ...

but what there is of the caudal fin is often confluent with the posterior dorsal and anal fins. There are normally two

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 ...

s, the anterior dorsal fin is quite high, the posterior quite low but is longer and takes up a greater proportion of the fish's of the back, species in the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Macrouroidinae Macrouroidinae is a subfamily of rattails from the family Macrouridae, it contains only two species in two genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as vir ...

have a single dorsal fin. The long

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 ...

is almost as long as the second dorsal fin is nearly as long as the posterior dorsal, and sometimes it is longer. The

pelvic 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 en ...

is inserted in the vicinity of the thorax and normally has 5-17 fin rays but are absent in '' Macrouroides''. The body is covered in small scales and if they have a

photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...

, it is usually on the midline of the abdomen just in front of the anus. The

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

of these fish is produced by

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

bioluminescent bacteria. The structure of the skull has been used to show their placing in the Gadiformes, but they differ from the typical cods in that they possess one stout spine in the anterior dorsal fin. The species in this family are mainly

benthopelagic The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

, they are found at depths of 200–2000 m, they occur on the sea bed and have a wide distribution from the Arctic to the Antarctic. The species in the Macrouridae normally live near the sea bed on the

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

, however, some species are bathypelagic or

mesopelagic The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins ...

, other species occur on the outer

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

. Their bodies are loose in texture rather than firm and they are weak swimmers. Some species are of commercial importance to fisheries. Coelorinchus tokiensis

Subfamilies

There are four subfamilies within the Macrouridae: *

Bathygadinae Bathygadinae is a subfamily of rattails in the family Macrouridae, the species of which are found in Atlantic, Indian and Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from t ...

: contains 2 genera and 26 species * Macrourinae: contains 28 genera and 370 species *

: contains 2

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genera *

Trachyrincinae Trachyrincinae is a subfamily of the family Macrouridae, also known as rattails. The subfamily contains two genera found in Atlantic, Indian and Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divis ...

contains 2 genera and 7 species

References

{{Taxonbar, from=Q766678 Gadiformes Taxa named by Charles Lucien Bonaparte Ray-finned fish families