''Chionodraco'' is a genus 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 hor ...

belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Channichthyidae The crocodile icefish or white-blooded fish comprise a family (Channichthyidae) of notothenioid fish found in the Southern Ocean around Antarctica. They are the only known vertebrates to lack hemoglobin in their blood as adults. Icefish populatio ...

, the

crocodile icefish The crocodile icefish or white-blooded fish comprise a family (Channichthyidae) of notothenioid fish found in the Southern Ocean around Antarctica. They are the only known vertebrates to lack hemoglobin in their blood as adults. Icefish populatio ...

es. They are found in 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-small ...

Taxonomy

''Chionodraco'' was first described as a genus in 1905 by the Swedish

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

Einar Lönnberg Axel Johann Einar Lönnberg (24 December 1865 – 21 November 1942) was a Swedish zoologist and conservationist. Lönnberg was born in Stockholm. He was head of the Vertebrate Department of the ''Naturhistoriska Riksmuseet'' (Swedish Natural Hi ...

when he described the ''Chaenichthys hamatus'' which he subsequently placed in a new

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus. The genus name is a

compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive struct ...

of ''chionos'' meaning "snow" and ''draco'' which means "dragon", Lönnberg did not explain this but it may allude to a relationship with the genus ''

Cryodraco ''Cryodraco'' is a genus of marine ray-finned fish belonging to the family Channichthyidae, the crocodile icefishes. They are found in the Southern Ocean. While ''C. antarcticus'' has minor commercial importance, ''C. atkinsoni'' and ''C. pappen ...

''.

Species

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

Chionodraco hamatus ''Chionodraco hamatus'' is a species of marine ray-finned fish belonging to the family Channichthyidae, the crocodile icefishes. It is found in the Southern Ocean. Taxonomy ''Chionodraco hamatus'' was first formally described in 1905 as ''Chaen ...

'' (Lönnberg, 1905) * ''

Chionodraco myersi ''Chionodraco myersi'', the Myer's icefish, is a species of marine ray-finned fish belonging to the family Channichthyidae, the crocodile icefishes. It is found in the Southern Ocean. Taxonomy ''Chionodraco myersi'' was first formally described ...

'' H. H. DeWitt & J. C. Tyler, 1960 (Myers' icefish) * ''

Chionodraco rastrospinosus The ocellated icefish (''Chionodraco rastrospinosus'') is a fish of the family Channichthyidae. It lives in the cold waters off Antarctica and is known for having transparent haemoglobin-free blood. ''C. rastrospinosus'' live in the Southern Oc ...

'' H. H. DeWitt & Hureau, 1979 (Ocellated icefish)

Characteristics

''Chionodraco'' icefishes may have the spine on the snout present or it is reduced to a small centrally placed knob. The

gill raker Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of the ...

s may bear teeth or are vestigial. The upper and lower jaws are of equal length, although the lower jaw may protrude. There are robust spines on the operculum with the other opercular bones each having a pair of spines where they join. The first and second

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s are separate and there are three

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. In 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 en ...

the outermost pair of fin rays are the longest and the tips are covered in thickened skin. 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 ...

is rounded. The 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 ...

of these fishes varies from in ''C. myersi'' to in ''C. rastrospinosus''.

Distribution and habitat

''Chionodraco'' contains two circum-antarctic species and one which is apparently confined to West Antarctica. They are

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

and

pelagic fish Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that do live on or near the bottom, and reef fish that are associated with coral reef ...

es found on the continental shelf and slope.

Biology

''Chionodraco'' icefishes are predatory, feeding on other fish species and on krill. They have a long post larval pelagic phase. In common with many other channichthyid fishes, reproduction in ''

'' involves laying eggs in a nest and parental guarding. Similar morphological features suggest that at least ''

'' has similar reproductive behaviours.

Fisheries

''Chionodraco'' icefishes are targeted by some commercial fisheries and are also taken as bycatch.

References

{{Taxonbar, from=Q2164125 Channichthyidae Perciformes genera Taxa named by Einar Lönnberg