''Chionodraco hamatus'' is a species 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 icefishes. It is 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 hamatus'' was first formally described in 1905 as ''Chaenichthys rhinoceratus hamatus'' 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 ...

with the type locality given as

Snow Hill Island Snow Hill Island is an almost completely snowcapped island, long and wide, lying off the east coast of the Antarctic Peninsula. It is separated from James Ross Island to the north-east by Admiralty Sound and from Seymour Island to the north b ...

Graham Land Graham Land is the portion of the Antarctic Peninsula that lies north of a line joining Cape Jeremy and Cape Agassiz. This description of Graham Land is consistent with the 1964 agreement between the British Antarctic Place-names Committee and ...

on the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...

. Lönnberg subsequent classified it in a new

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Chionodraco ''Chionodraco'' is a genus of marine ray-finned fish belonging to the family Channichthyidae, the crocodile icefishes. They are found in the Southern Ocean. Taxonomy ''Chionodraco'' was first described as a genus in 1905 by the Swedish zoologist ...

'' as its only species so ''C. hamatus'' is 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 specimen ...

of that genus by

monotypy 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 ...

. Some authorities regard ''C. kathleenae'' as a valid species. The specific name ''hamatus'' means “hooked”, a reference to the hooked operculum spines.

Description

''Chionodraco hamatus'' has a robust, backwards pointing spine on its snout. In larger individuals the ridges above the eyes are roughly textured. The dorsal fin has 5 to 7 spines and 38 to 42 soft rays while the anal fin has 33 to 38 soft rays. The overall colour is greyish on the upper body and whitish on the belly with 2 diagonal stripes on the cheek. Mature males have dark fins. This species attains a maximum total length of .

Distribution and habitat

''Chionodraco hamatus'' is found in the cold waters of the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

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 contine ...

. This species lives in the demersal zone, and can be found at a depth range of 4 to 600 metres.

Biology

''Chionodraco hamatus'' feeds most on small fish, krill, and fish larvae. Spawning appears to occur during the summer and females have a

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...

of 2,900 to 4,200

oocytes An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ge ...

. In common with many other channichthyid fishes, reproduction in ''Chionodraco hamatus'' involves laying eggs in a nest and parental guarding. Male prepares a nest and courts the female. Egg deposition (and presumably fertilization too) takes place at night. Female remains in the nest, guarding and fanning the eggs. Hatching takes place over a prolonged period of time. Male seems not to be involved in the care of the eggs. The larvae have a long pelagic phase.

References

{{Taxonbar, from=Q2353844 hamatus Fish of the Southern Ocean Fish described in 1905 Taxa named by Einar Lönnberg Fish of Antarctica