''Dacodraco'' is 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 "unispe ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 h ...

belonging to the

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

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, its only member is ''Dacodraco hunteri''. This species 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

''Dacodraco'' was first described as a genus in 1916 by the English-born Australian ichthyologist Edgar Ravenswood Waite when he was describing its only species ''Dacodraco hunteri''. The type locality of ''D. hunteri'' is Queen Mary Land, off the Shackleton Ice Shelf at 65°06'S, 96°13'E. The genus name is a compound of ''dakos'' which means a "beast that bites" and ''draco'' meaning "dragon", a common suffix in generic names of Notothenioids. Waite did not explain the reason for using ''dakos'' but it may refer to the single row of teeth in each jaw with an spaced line of large canines to the inside of them. The specific name honours the Australian

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

John G. Hunter of Sydney University who was chief biologist at the main base of the Australian Antarctic Expedition on the Adelie Coast.

Description

''Dacodraco'' has a spine on its snout, but this has been reduced to a small knob or blunt spine. The opercuum has an obvious ridge which ends in a flattened spine towards the rear, the other opercular bones do not have spines. There are two lateral lines which do not have any bony plates, the upper and lower lateral lines are present but there is no middle line. The upper and lower jaws are curved so that a gap forms along the length of the closed mouth. The second fin ray in the pelvic fin is the longest. 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 c ...

is widely separated from the second dorsal fin. The dorsal fins have 2-3 spines and 32-33 soft rays while the anal fin has 29-32 soft rays. This species attain a maximim

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 . The overall colour is reddish-grey with a brown tinge. There are 4 dark cross-bars on body and a fifth dark bar at the base of 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 ...

with a vague dark blotch positioned over the third, fourth and 5th bars. The first dorsal fin and pelvic fins are dark coloured while the other fins are blackish. The juveniles are typically pale but still have 5 distinct dark cross-bars.

Distribution, habitat and biology

''Dacodraco'' is a rare species which is probably circumAntarctic in its distribution. It is a bathydemersal species which is found at depths between , although the pelagic larvae can be found at > The larvae spend a long time in their pelagic phase. ''D. hunteri'' skeleton is not heavily

ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

and its skull has a large proportion of cartilage. The notochord partly persists in adults and the spine has reduced amounts of bone because the

centra Centra is a convenience shop chain that operates throughout Ireland. The chain operates as a symbol group owned by Musgrave Group, the food wholesaler, meaning the stores are all owned by individual franchisees. The chain has three different ...

are not wholly constricted. It is one of the lightest notothenioids and probably spends almost all of its life in the water column. This predatory species has a diet which comprises relatively large individuals of the

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'').

References

{{Taxonbar, from1=Q2435043, from2=Q2788295 Channichthyidae Monotypic fish genera Fish described in 1916 Fish of the Southern Ocean Taxa named by Edgar Ravenswood Waite