''Notothenia'' 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 ...

of marine

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 ...

es belonging to 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 ...

Nototheniidae, 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 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...

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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

Taxonomy

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

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

and Arctic explorer John Richardson when he described ''N. coriiceps'' which was later designated as 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 ...

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. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Nototheniinae, but the 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' 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'' F. W. Hutton, 1875 (Maori chief) * '' Notothenia coriiceps'' J. Richardson, 1844 (black rockcod) * '' Notothenia cyanobrancha'' J. Richardson, 1844 (blue rockcod) * '' Notothenia microlepidota'' F. W. Hutton, 1875 (black cod) * '' Notothenia neglecta'' Nybelin, 1951 (yellowbelly rockcod) * '' Notothenia rossii'' J. Richardson, 1844 (marbled rockcod) * '' Notothenia trigramma'' Regan, 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 lines 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 moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s are notably larger than 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 ...

s while the caudal fin 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, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

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 p ...

s that allow them to thrive in such inhospitable

habitat In ecology, habitat refers to the array of resources, 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 manifestation of its ...

, like antifreeze proteins 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 (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

. 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

{{Authority control Nototheniidae Perciformes genera Taxa named by John Richardson (naturalist)