''Thymallus'', commonly known as graylings, is a

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 ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

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 ...

and the only genus within 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 ...

Thymallinae of the

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 ...

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

. Although all ''Thymallus'' species can be generically called graylings, without specific qualification the term "grayling" typically refers to the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

Thymallus thymallus ''Thymallus thymallus'', the grayling or European grayling, is a species of freshwater fish in the salmon family (biology), family Salmonidae. It is the only species of the genus ''Thymallus'' (the graylings) native to Europe, where it is widespr ...

'', the European grayling.

Name

The name of the genus ''Thymallus'' first given to grayling (''T. thymallus'') described in the 1758 edition of ''Systema Naturae'' by Swedish zoologist

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

originates from the faint smell of the herb

thyme Thyme () is a culinary herb consisting of the dried aerial parts of some members of the genus ''Thymus (plant), Thymus'' of flowering plants in the mint family Lamiaceae. Thymes are native to Eurasia and north Africa. Thymes have culinary, medici ...

, which emanates from the flesh. ''Thymallus'' derives from the

Greek Greek may refer to: 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 of all kno ...

θύμαλλος, "thyme smell".

Species

According to

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

, 14 species are placed in this genus. However, views differ on their taxonomic rank. * ''

Thymallus arcticus The Arctic grayling (''Thymallus arcticus'') is a species of freshwater fish in the salmon family (biology), family Salmonidae. ''T. arcticus'' is widespread throughout the Arctic Ocean, Arctic and Pacific Ocean, Pacific drainages in Canada, A ...

'' (

Pallas Pallas may refer to: Astronomy * 2 Pallas asteroid ** Pallas family, a group of asteroids that includes 2 Pallas * Pallas (crater), a crater on Earth's moon Mythology * Pallas (Giant), a son of Uranus and Gaia, killed and flayed by Athena * Pa ...

, 1776) - Arctic grayling * '' Thymallus baicalensis'' Dybowski, 1874 - Baikal black grayling * '' Thymallus brevipinnis'' Svetovidov ( ru), 1931 - Baikal white grayling * '' Thymallus brevirostris'' Kessler, 1879 - Mongolian grayling * '' Thymallus burejensis''

Antonov Antonov (d/b/a Antonov Company, formerly the Aeronautical Scientific-Technical Complex named after Antonov or Antonov ASTC, and earlier the Antonov Design Bureau, for its chief designer, Oleg Antonov) is a Ukrainian aircraft manufacturing and ...

, 2004 - Bureya grayling * '' Thymallus flavomaculatus'' Knizhin,

& Weiss, 2006 - yellow-spotted grayling * '' Thymallus grubii'' Dybowski, 1869 - Amur grayling *'' Thymallus mertensii''

Valenciennes Valenciennes (, also , , ; ; or ; ) is a communes of France, commune in the Nord (French department), Nord Departments of France, department, Hauts-de-France, France. It lies on the Scheldt () river. Although the city and region experienced ...

, 1848 - Kamchatka grayling * '' Thymallus nigrescens'' Dorogostaisky, 1923 - Kosogol grayling * '' Thymallus pallasii'' Valenciennes, 1848 - East Siberian grayling * '' Thymallus svetovidovi'' Knizhin & Weiss, 2009 - Upper Yenisei grayling * ''

'' (

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of ''Systema Naturae'', the starting point of modern zoologic ...

) - European grayling (

) * '' Thymallus tugarinae'' Knizhin, Antonov, Safronov & Weiss, 2007 - Lower Amur grayling * '' Thymallus yaluensis'' T. Mori, 1928 - Yalu grayling Modern reviewsWeiss, S. J., D. V. Gonçalves, G. Secci-Petretto, G. K. Englmaier, A. Gomes-Dos-Santos, G. P. J. Denys, H. Persat, A. Antonov, C. Hahn, E. B. Taylor and E. Froufe (2021) Global systematic diversity, range distributions, conservation and taxonomic assessments of graylings (Teleostei: Salmonidae; ''Thymallus'' spp.). ''Organisms Diversity & Evolution'': -18 (published online 25 Nov. 2020) and the ''

Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously up ...

'' also list additional species including '' Thymallus nikolskyi'' , '' Thymallus baicalolenensis'' and '' Thymallus ligericus'' . An old controversy exists over the status of Baikal black vs white graylings, ''T. baicalensis'' and ''T. brevipinnis''. Modern research supports the view that they are not separate taxa, but alternative ecological forms of ''T. baicalensis''.

Distribution

The fishes of this genus are native to the northern parts of the

Palearctic The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa. Th ...

and

Nearctic realm The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

s, ranging from the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

and northern

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

across

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

, as well as northern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. ''T. thymallus'', the grayling, is widespread in Europe, and ''T. arcticus,'' the Arctic grayling, is widespread throughout Eurasia east of the

Ural Mountains The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.

and in the Nearctic. The other species have more localized ranges in northern Asia.

Appearance

''Thymallus'' species are distinguished from other members of the salmonid family by their larger scales, their small mouths with

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

on the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

ry bone, and most striking of all, their showy, sail-like

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. This fin is longer in males and highly colourful, with spots of red, orange, purple or green. The body is also colourful; the dorsal surface is a dark purplish to bluish black or gray, grading to dark blue or silver gray on the flanks and gray or white on the belly. The body is further decorated with a smattering of small dark spots; these are much more numerous in juveniles. The longest of the graylings is the Arctic grayling, ''T. arcticus'', at a maximum length of and a maximum weight of . ''T. thymallus,'' while somewhat shorter - - may weigh significantly more, . The fishes of this genus may live for 18 years or more.

Ecology and reproduction

These fishes require cool, well-oxygenated water, preferably with a swift current; they are found in large, sandy- or gravel-bottomed rivers and lakes, but ''T. thymallus'' may occasionally be found in

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

conditions. Generally

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

, they feed primarily on

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

, and

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

. The grayling species, typically for

salmonids Salmonidae (, ) is a family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic a ...

, spawn in rivers and do not guard their brood, although they do conceal their eggs in silt. The spawning behavior of the Arctic grayling may be typical for the genus ''Thymallus''. As they are highly sensitive to changes in water quality, ''Thymallus'' fishes may be considered

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

; ''T. arcticus'' has largely disappeared from the

Great Lakes Basin The Great Lakes Basin consists of the Great Lakes and the surrounding lands of the states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin in the United States, and the province of Ontario in Canada, whose di ...

Human use

Due to their agreeable taste and attractive form, the grayling species are valued as food and game fishes, and they are occasionally seen in public aquaria. The most economically important of these fishes, for which

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish farm ...

and

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

operations exist, are the grayling (''T. thymallus'') and the Arctic grayling (''T. arcticus'').

References

{{Authority control Extant Pleistocene first appearances Ray-finned fish genera Fauna of the Holarctic realm