''Notothenia'' is a

genus 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 nom ...

of marine

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 h ...

es 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 purpose of the family is to maintain the well-being of its members and of society. Idea ...

Nototheniidae : ''In some scientific literature, the term "cod icefish" is used to identify members of this family. This should not be confused with the term "icefish," which refers to the "white-blooded" fishes of the family Channichthyidae. See Icefish (disam ...

, the notothens or cod icefishes with the species in this genus often having the common name of rockcod. They are native to the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...

and other waters around

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

Taxonomy

''Notothenia'' was first formally described as a genus in 1844 by the Scottish

naval surgeon A naval surgeon, or less commonly ship's doctor, is the person responsible for the health of the ship's company aboard a warship. The term appears often in reference to Royal Navy's medical personnel during the Age of Sail. Ancient uses Speciali ...

, naturalist and

Arctic explorer Arctic exploration is the physical exploration of the Arctic region of the Earth. It refers to the historical period during which mankind has explored the region north of the Arctic Circle. Historical records suggest that humankind have explored ...

John Richardson when he described ''N. coriiceps'' which was later designated as the

type species In 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 species that contains the biological type specim ...

of the genus. Some authorities place this taxon in the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus Genus ( plural genera ) is a taxonomic rank used in the biological classifica ...

Nototheniinae, but the 5th edition of ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

'' does not include subfamilies in the Nototheniidae. The name of the genus is a compound of ''notos'' meaning “south” and ''thenia'' which means “coming from”, an allusion to the high southern latitudes these fishes are found at.

Species

Seven recognized species are in this genus: * ''

Notothenia angustata ''Notothenia angustata'', the Maori chief or black cod, is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Southern Ocean Taxonomy ''Notothenia angustata'' was first ...

'' F. W. Hutton, 1875 (Maori chief) * '' Notothenia coriiceps'' J. Richardson, 1844 (black rockcod) * ''

Notothenia cyanobrancha ''Notothenia cyanobrancha'', the blue rockcod, bluegill notothen, or bluegill rockcod, is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Kerguelen and Heard Islands ...

'' J. Richardson, 1844 (blue rockcod) * ''

Notothenia microlepidota ''Notothenia microlepidota'', the black cod or small-scaled cod, is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Pacific waters around New Zealand and Macquarie Is ...

'' F. W. Hutton, 1875 (black cod) * ''

Notothenia neglecta ''Notothenia neglecta'', the yellowbelly rockcod, is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is found in the Southern Ocean in Antarctica. They are omnivorous, and are found i ...

'' Nybelin, 1951 (yellowbelly rockcod) * ''

Notothenia rossii The marbled rockcod (''Notothenia rossii'') is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Southern Ocean, where it can be found at depths from . This is a comm ...

'' J. Richardson, 1844 (marbled rockcod) * '' Notothenia trigramma''

Regan The family name Regan, along with its cognates O'Regan, O Regan, Reagan, and O'Reagan, is an Anglicized form of the Irish surname Ó Riagáin or Ó Ríogáin, from Ua Riagáin. The meaning is likely to have originated in ancient Gaelic ''ri'' ...

, 1913

Characteristics

''Notothenia'' fishes have oblong bodies which are compressed towards the tail with a large head, small eyes and a large mouth. The lower jaw does not protrude and the mouth extends as far back as the middle of the eye. There are moderately sized teeth in the jaws with no large canine-like teeth. There are two

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

s consisting of tubed scales, one on the upper body and the other on the mid-flank. Most of the scales on the body are smooth while much of the head is naked. The

pectoral 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 ...

s are notably larger than 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 ...

s while 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 ...

may be rounded, truncate one emarginate. They vary in maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

from in the blue rockcod to in the marbled rockcod.

Distribution and habitat

''Notothenia'' rockcods are found in the Southern Ocean where there are four species with two species in the southwestern Pacific Ocean and a single species in the southwestern Atlantic Ocean. The young fish are pelagic and the adults are benthic.

Biology

''Notothenia'' rockcods have some

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s that allow them to thrive in such inhospitable

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

, like

antifreeze protein Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small ...

s in their blood and ample fat to insulate them against heat loss and to offset their lack of a

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth wit ...

. They are benthic predators feeding on invertebrates and smaller fishes, although algae are consumed in large quantities too. The pelagic fingerlings allow the wide dispersal of the species around the Southern Ocean.

Fisheries

''Notothenia'' rockcods are targeted by some fisheries, with ''N. rossi'' being an important commercially fished species.

References

{{Taxonbar, from=Q2430834 Nototheniidae Perciformes genera Taxa named by John Richardson (naturalist)