''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 "unispec ...

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 ...

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 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 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 ...

Edgar Ravenswood Waite when he was describing its only species ''Dacodraco hunteri''. The type locality of ''D. hunteri'' is

Queen Mary Land Queen Mary Land or the Queen Mary Coast () is the portion of the coast of Antarctica lying between Cape Filchner, in 91° 54' E, and Cape Hordern, at 100° 30' E. It is claimed by Australia as part of the Australian Antarctic Territory. It w ...

, off the

Shackleton Ice Shelf Shackleton Ice Shelf is an extensive ice shelf fronting the coast of East Antarctica from 95° E to 105° E. It extends for an along-shore distance of about , projecting seaward about in the western portion and in the east. It occu ...

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 The University of Sydney (USYD), also known as Sydney University, or informally Sydney Uni, is a public research university located in Sydney, Australia. Founded in 1850, it is the oldest university in Australia and is one of the country's six ...

who was chief biologist at the main base of the

Australian Antarctic Expedition The Australasian Antarctic Expedition was a 1911–1914 expedition headed by Douglas Mawson that explored the largely uncharted Antarctic coast due south of Australia. Mawson had been inspired to lead his own venture by his experiences on Erne ...

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 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 epithelial ...

s 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 Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

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 conv ...

is widely separated from the second dorsal fin. The dorsal fins have 2-3 spines and 32-33 soft rays while 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 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 se ...

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 Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They occ ...

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 Cell (biology), cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes ...

and its skull has a large proportion of

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

. The

notochord In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consis ...

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