The ploughfish (''Gymnodraco acuticeps'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

Antarctic dragonfish The Bathydraconidae, or the Antarctic dragonfishes, are a family (taxonomy), family of marine ray-finned fishes, notothenioids belonging to the Perciform suborder Notothenioidei. The family comprises four genera. These fishes are endemic to deep ...

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 ...

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. ...

. It is found at depths of from over the

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

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 islan ...

. This species is the only known member of its

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 ...

Taxonomy

The ploughfish was first formally described in 1902 by the Belgian-born British

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, 35,800 species of fish had been described as of March 2 ...

George Albert Boulenger George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botani ...

with the type locality given as Cape Adare in Antarctica, Boulenger placed this species in a new monotypic genus ''Gymnodraco'', it is still the only known species in that genus. The genus name is a compound of ''gymnos'' which means "bare" or "naked", a reference to the almost complete lack of scales on the body, and ''draco'' meaning "dragon" and is a common suffix used for notothenioid fish names. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''acuticeps'' means "pointed head" an allusion to the strongly depressed head with its sharply pointed snout.

Description

The ploughfish has a naked body, the only scales being those on the two

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 epithelia ...

s with the middle lateral line only has perforated scales, which is depressed at the head and compressed towards the tail. The head is triangular in shape with a long, pointed snout. There is a strong ridge on the operculum which forms a spine with a hooked process at its rear end and there is another spine on the soboperclulum and the preoperculum is smooth. The jaws have canine-like teeth at the

mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...

, with bands of small, slightly decurved conical teeth behind them. The lower jaw protrudes beyond the upper with its front canine-like teeth exposed. There are 27-30 soft rays in the

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

and 23-26 in the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

. In alcohol the overall colour of the body is dark brown, becoming paler on the underside. The head is marked with small spots and the body with dark blotches, although these may fade over time. The fins are dark brown to blackish and there is a patch of dark colour around the

anus In mammals, invertebrates and most fish, the anus (: anuses or ani; from Latin, 'ring' or 'circle') is the external body orifice at the ''exit'' end of the digestive tract (bowel), i.e. the opposite end from the mouth. Its function is to facil ...

. This species attains a 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 ...

of and a maximum weight of .

Distribution and habitat

The ploughfish is found in the Southern Ocean and has been recorded from the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin 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 Antarctica. ...

South Shetland Islands The South Shetland Islands are a group of List of Antarctic and subantarctic islands, Antarctic islands located in the Drake Passage with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the n ...

and the

of Antarctica, it probably has a circum-Antarctic range. However, as yet, it has not been recorded from West Antarctica. This is a

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 o ...

species which is found at depths of , although it is rare below .

Biology

Ploughfish spawn during September off

Adélie Land Adélie Land ( ) or Adélie Coast is a Territorial claims in Antarctica, claimed territory of France located on the continent of Antarctica. It stretches from a portion of the Southern Ocean coastline all the way inland to the South Pole. Franc ...

and hatching probably occurs in the Spring as larvae with a length of were collected in the

Bransfield Strait Bransfield Strait or Fleet Sea () is a body of water about wide extending for in a general northeast – southwest direction between the South Shetland Islands and the Antarctic Peninsula. History The strait was named in about 1825 by James W ...

in mid-November and juveniles have been taken as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

krill Krill ''(Euphausiids)'' (: krill) are small and exclusively marine crustaceans of the order (biology), order Euphausiacea, found in all of the world's oceans. The name "krill" comes from the Norwegian language, Norwegian word ', meaning "small ...

catches in February and March. Females have around 5,000 eggs in each ovary and when ripe they have a diameter of . Studies of diet have found that off the South Shetland Islands they ate only the krill species '' Euphasia superba'' but in

McMurdo Sound The McMurdo Sound is a sound in Antarctica, known as the southernmost passable body of water in the world, located approximately from the South Pole. Captain James Clark Ross discovered the sound in February 1841 and named it after Lieutenant ...

their diet was more varied and included mostly fish, with amphipods being the next most important food type, then fish eggs and then polychaetes. The fish taken included '' Pleuragramma antarcticum'', '' Pagothenia borchgrevinki'' and '' Trematomus nicolai''.

References

{{Taxonbar, from=Q2774269 Bathydraconidae Fish of the Southern Ocean Fish of Antarctica Fish described in 1902 Taxa named by George Albert Boulenger