Nototheniidae
Encyclopedia
The cod icefishes or nothothens are the family
Nototheniidae of acanthopterygian
fish
es, containing about 50 species in 13 genera. They are traditionally placed in the perciform assemblage together with their relatives, but like every lineage in the "Perciformes" their actual relationships are not yet determined with certainty.
They are largely found in the Southern Ocean
and off the coast of Antarctica. As the dominant Antarctic fish taxa, they occupy both sea bottom and water column ecological niches. Although lacking a gas bladder
, they have undergone a depth-related diversification, such as increase in fatty tissues and reduced mineralization of the bones, resulting in a body density approaching neutral, to fill a variety of water column niches. It is thought that the spleen may be used to remove ice crystals from circulating blood. As the chilly subantarctic waters averages –1 to 4 degrees Celsius, most Antarctic species have antifreeze glycoproteins
in their blood and other body fluids.
Some species exhibit polymorphism, for example, the circum-Antarctic Trematomus newnesi exists as two morphs in the Ross Sea
, the typical morph and a large mouth/broad headed morph.
As the major fish resource in the Southern Ocean, nototheniids are under increasing pressure from commercial fishing.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Nototheniidae of acanthopterygian
Acanthopterygii
Acanthopterygii is a superorder of bony fishes in the class Actinopterygii. Members of this superorder are also known as the ray-finned fishes for the characteristic sharp, bony rays in their fins; however this name is also often given to the class Actinopterygii as a whole.Orders:* Order...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es, containing about 50 species in 13 genera. They are traditionally placed in the perciform assemblage together with their relatives, but like every lineage in the "Perciformes" their actual relationships are not yet determined with certainty.
They are largely found in the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
and off the coast of Antarctica. As the dominant Antarctic fish taxa, they occupy both sea bottom and water column ecological niches. Although lacking a gas bladder
Gas bladder
The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming...
, they have undergone a depth-related diversification, such as increase in fatty tissues and reduced mineralization of the bones, resulting in a body density approaching neutral, to fill a variety of water column niches. It is thought that the spleen may be used to remove ice crystals from circulating blood. As the chilly subantarctic waters averages –1 to 4 degrees Celsius, most Antarctic species have antifreeze glycoproteins
Antifreeze protein
Antifreeze proteins or ice structuring proteins refer to a class of polypeptides produced by certain vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. AFPs bind to small ice crystals to inhibit growth and recrystallization of ice that would otherwise be...
in their blood and other body fluids.
Some species exhibit polymorphism, for example, the circum-Antarctic Trematomus newnesi exists as two morphs in the Ross Sea
Ross Sea
The Ross Sea is a deep bay of the Southern Ocean in Antarctica between Victoria Land and Marie Byrd Land.-Description:The Ross Sea was discovered by James Ross in 1841. In the west of the Ross Sea is Ross Island with the Mt. Erebus volcano, in the east Roosevelt Island. The southern part is covered...
, the typical morph and a large mouth/broad headed morph.
As the major fish resource in the Southern Ocean, nototheniids are under increasing pressure from commercial fishing.
Genera and selected species