Macrouridae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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

cod Cod (: cod) is the common name for the demersal fish genus ''Gadus'', belonging to the family (biology), 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 ''Gad ...

-like fish, the Gadiformes. 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 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 ...

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 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, the anterior dorsal fin is quite high, the posterior quite low but is longer and takes up a greater proportion of the fish's 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 botanical subfamily names with "-oideae", and zo ...

Macrouroidinae have a single dorsal fin. The long

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 ...

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

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

is inserted in the vicinity of the thorax and normally has 5–17 fin rays but these are absent in '' Macrouroides''. The body is covered in small scales and if they have a photophore, it is usually on the midline of the abdomen just in front of the anus. The

bioluminescence Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorgani ...

of these fish is produced by

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

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, 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, however, some species are bathypelagic or

mesopelagic The mesopelagic zone (Greek language, 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 ...

, 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 islan ...

. 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: contains 2 genera and 26 species * Macrourinae: contains 28 genera and 370 species * Macrouroidinae: 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 "unisp ...

genera * Trachyrincinae contains 2 genera and 7 species The earliest known genus is '' Bobbitichthys'' Schwarzhans, Milàn & Carnevale, 2021, a stem-macrourid from the middle Paleocene of Denmark. A well-preserved skull of an indeterminate macrourid is known from the

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 ...

-aged La Meseta Formation of Antarctica. The extinct genus '' Bolbocara''

Jordan Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...

, 1927 is known from an articulated fossil skeleton from the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

of California, while '' Razelaina'' Carnevale, 2007 is known from the Late Miocene of

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

References

{{Taxonbar, from=Q766678 Euteleostei families Taxa named by Charles Lucien Bonaparte