''Polymixia'' is the only

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of the

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 ...

Polymixiiformes The beardfishes consist of a single extant genus, ''Polymixia'', of deep-sea marine ray-finned fish named for their pair of long hyoid barbels. They are classified in their own order Polymixiiformes . But as Nelson says, "few groups have been sh ...

and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, Indian and western

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

Oceans. They are bottom-dwelling fish, found down to about . Most are relatively small fish, although one species is over in length. They can be considered " living fossils" due to being the only surviving members of the once-diverse order Polymixiiformes.

Classification

There are currently 12 recognized species in this genus: * ''

Polymixia berndti ''Polymixia berndti'' is a species of beardfish found in the Indian and Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north ...

'' C. H. Gilbert, 1905 (Pacific beardfish) * ''

Polymixia busakhini ''Polymixia'' is the only extant taxon, extant genus of the Order (biology), order Beardfish, Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subt ...

'' Kotlyar, 1993 (Busakhin's beardfish) * '' Polymixia carmenae'' Caixeta, Oliveira & de Melo, 2024 (Brazilian beardfish) * '' Polymixia fusca'' Kotthaus, 1970 * '' Polymixia hollisterae'' Grande & Wilson, 2021 (Bermuda beardfish) * '' Polymixia japonica'' Günther, 1877 (Silver eye) * '' Polymixia longispina'' S. M. Deng, G. Q. Xiong & H. X. Zhan, 1983 * '' Polymixia lowei'' Günther, 1859 (Beardfish) * ''

Polymixia melanostoma ''Polymixia'' is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the Atlantic, Indian an ...

'' Fan, Su, Lin, Chang & Lin 2024 * ''

Polymixia nobilis ''Polymixia nobilis'', the stout beardfish, is a species of beardfish. This species can grow over TL. The species' dorsal fin has five spines and 34-27 soft rays and 10-13 gill rakers. The habitat of the fish is in the benthic zone. Habitat ' ...

'' R. T. Lowe, 1838 (Stout beardfish) * ''

Polymixia salagomeziensis ''Polymixia'' is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the Atlantic, Indian an ...

'' Kotlyar, 1991 * ''

Polymixia sazonovi ''Polymixia'' is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the Atlantic, Indian an ...

'' Kotlyar, 1992 * ''

Polymixia yuri ''Polymixia'' is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the Atlantic, Indian an ...

'' Kotlyar, 1982 The extinct species ''

Polymixia polita ''Polymixia'' is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subtropical waters of the Atlantic, Indian an ...

'' Schwarzhans, 2012 is known from fossil

otoliths An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, i ...

from the early and late

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), ...

of Germany and Austria. Another otolith-based taxon that may possibly belong to this genus, ''Polymixia''? ''harderi'' (Schwarzhans, 2003) is known from the late

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 early Paleocene of Denmark, in addition to a potential earlier record from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

, USA; this may suggest

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

origins for the genus.

References

Polymixiiformes Ray-finned fish genera {{Polymixiiformes-stub Extant Danian first appearances