The Bathydraconidae, or the Antarctic dragonfishes, are a
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
of marine
ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...
es, notothenioids belonging to the
Perciform suborder
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
Notothenioidei
Notothenioidei is one of 19 suborders of the order Perciformes. The group is found mainly in Antarctic and Subantarctic waters, with some species ranging north to southern Australia and southern South America. Notothenioids constitute approximat ...
. The family comprises four genera. These fishes are endemic to deep waters off
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. ...
.
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Taxonomy
Bathydraconidae was first formally described as a family in 1913 by the English 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 ...
Charles Tate Regan
Charles Tate Regan (1 February 1878 – 12 January 1943) was a British ichthyology, ichthyologist, working mainly around the beginning of the 20th century. He did extensive work on fish classification schemes.
Born in Sherborne, Dorset, he was ...
in his report on the fishes collected on the Scottish National Antarctic Expedition to the Royal Society of Edinburgh
The Royal Society of Edinburgh (RSE) is Scotland's national academy of science and letters. It is a registered charity that operates on a wholly independent and non-partisan basis and provides public benefit throughout Scotland. It was establis ...
.[ He used the genus '' Bathydraco'', which had been described by Albert Gunther in 1878 as a ]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 "unisp ...
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 ...
with '' B. antarctica'' as its type species
In International_Code_of_Zoological_Nomenclature, 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 spe ...
, as the type genus
In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearin ...
.clades
In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...
; Bathydraconinae which includes ''Bathydraco'', '' Prionodraco'' and '' Racovitzia''; Gymnodraconinae which includes '' Gymnodraco'', '' Psilodraco'' and '' Acanthodraco''); and Cygnodraconinae including '' Cygnodraco'', '' Gerlachea'' and '' Parachaenichthys''. However, this subdivision is not recognised in the 5th edition of ''Fishes of the World
''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...
''.
Genera
The following genera are classified within the family Bathydraconidae:
Characteristics
Bathydraconidae species have elongate, slender bodies and may be separated from the other notothenioid families by the lack of a spiny first dorsal fin. Their bodies may be stocky, nearly cylindrical or rather depressed at the front and compressed at the rear. There is a single 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 ...
which has a long base and lacks any spines. 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 ...
is typically shorter based than the dorsal fin, again having no spines. The pectoral fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...
s are well developed while the pelvic fin
Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...
s contain 1 spine and 5 branched fin rays, beginning to the front of the pectoral fins. The head is moderate to large in size, being depressed in some species. They have a long snout which is flattened or even slightly depressed and is typically short and pointed. They have large mouths which can extend as far as the level of the middle of the eye. The jaws normally have small, conical teeth and occasionally canines, there are usually no teeth elsewhere in the mouth. They have a single external nostril. The operculum may have a rearwards directed hooked or spine, it may be unarmed. The bodies may have scales, typically ctenoid, bony plates or be naked. They can have 1, 2, 3 or 5 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 made up of tubular, pored or pitted scales, and these are occasionally interlinked.
Distribution, habitat and biology
Bathydraconidae species are benthopelagic fishes found in 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 ...
waters. They are not fished commercially and little is known about them.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 ...
and slope of Antarctica, but some have been reported from the Antarctic and sub-Antarctic Islands. They inhabit from shallow, inshore waters, although some have been found as deep as . One species, '' Gymnodraco acuticeps'', has been found 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 ...
living at shallow depths under sea ice
Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...
, this species may even live under the Ross Ice Shelf
The Ross Ice Shelf is the largest ice shelf of Antarctica (, an area of roughly and about across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than long, and between high ...
.[
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References
{{Authority control
Notothenioidei