''Gvozdarus svetovidovi'', the naked-head toothfish, 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 ...

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. It is found in the

Ross Ross or ROSS may refer to: People * Clan Ross, a Highland Scottish clan * Ross (name), including a list of people with the surname or given name Ross, as well as the meaning * Earl of Ross, a peerage of Scotland Places * RoSS, the Republic of Sou ...

and

Cooperation Cooperation (written as co-operation in British English) is the process of groups of organisms working or acting together for common, mutual, or some underlying benefit, as opposed to working in competition for selfish benefit. Many animal a ...

Seas, probably south of the Antarctic Polar Front from

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

waters down to depths of 550 m (1,804 ft), though it is normally found in a pelagic environment.

Taxonomy

''Gvozdarus svetovidovi'' was first formally described in 1989 by the Russian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Arkady Vladimirovich Balushkin Arkady (russian: Арка́дий, Arkadiy) is a Slavic masculine given name, ultimately derived from the Greek name Αρκάδιος, meaning “from Arcadia”. The Latin equivalent is Arcadius. Notable people with the name include: People: *Ark ...

with the type locality given as the

Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who vi ...

at 73°36'S, 171°00'E, at a depth of . When the genus ''Gvozdarus'' was described this species was the only species in the genus and was, therefore, its

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 ...

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 ...

. A second species, ''Gvozdarus balushkini'', has since been added to the genus. The specific name honours Anatoly Nikolaevich Svetovidov who was head of the Laboratory of Ichthyology at the

USSR Academy of Sciences The Academy of Sciences of the Soviet Union was the highest scientific institution of the Soviet Union from 1925 to 1991, uniting the country's leading scientists, subordinated directly to the Council of Ministers of the Soviet Union (until 1946 ...

Description

''Gvozdarus svetovidovi'' has an elongate, fusiform body which is broadest at the front. The head is widest at its rear with a flat and wide space between the eyes and a snout which is longer than the diameter of its eyes. It has a large mouths which extends to the front of the pupil. The lower jaw protrudes slightly and both jaws have canine-like teeth with an inner patch near the jaw joint in the upper jaw. The body is covered in

ctenoid A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as ...

scales but the head is naked. The first

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 ...

holds 7 spines, the second dorsal fin has 30 soft rays and the

anal 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 ...

has 31 soft rays. This species is thought to attain a 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 . Their color is pale brown on the lower body while the head, back and flanks are dark. The dorsal fins are paler with transparent membranes. The

pelvic The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

and anal fins are light while the mouth and gill cavity are dark.

Ecology

This species is a large, pelagic

piscivore A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...

(fish-eating species, indicated by remains of the pelagic

Antarctic silverfish The Antarctic silverfish (''Pleuragramma antarctica''), or Antarctic herring, 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 and the only truly pela ...

''(Pleuragramma antarcticum)'' found in stomachs).

Commercial importance

This species is of no importance to

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

References

{{taxonbar, from=Q3762790 Nototheniidae Fish of the Southern Ocean Fish described in 1989