Antarctic fish

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Antarctic fish
Chionodraco hamatus

Chionodraco hamatus

Systematics
Sub-cohort : Neoteleostei
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Perch-like (Perciformes)
Subordination : Antarctic fish
Scientific name
Notothenioidei
Jordan , 1923

The subordination of the Antarctic fish (Notothenioidei) is a group of perch-like . It represents 75 percent of the fish species living in Antarctic waters . Most are bottom fish, and some live in the open water.

features

In most cases, Antarctic fish externally resemble the bullheads (Cottidae) of the Northern Hemisphere. Your body is covered with round or comb scales. With the exception of the scales along the sideline , however, they can also be scaleless. Usually there are two or three side lines, occasionally only one (as with all ice fish (Bovichtidae)). Ribs are poorly developed or completely absent. The epineuralia (bones, "upper ribs"), however, are well developed. A swim bladder is missing. Antarctic fish only have one nostril on each side of their heads (most bony fish have two). The palate is usually edentulous (exception: ice fish). The number of Branchiostegal rays is 5 to 9. The ventral fins have a fin spine and five, more rarely four branched soft rays, the caudal fin 10 to 19, usually less than 15 main fin rays. The hard rays of the dorsal fin are mostly non-piercing.

evolution

The Antarctic fish are an example of adaptive radiation , the emergence of countless new species from a parent species through adaptation to special living conditions and the exploitation of ecological niches. Geographical isolation and the lack of natural enemies favor the diversification.

Decisive for their adaptation to the inhospitable habitat was probably a key evolutionary innovation during a phase of global cooling and the increasing glaciation of the Antarctic around 35 million years ago. Many fish that had previously lived in the warm southern ocean became extinct. So-called anti-frost proteins , however, enabled the Antarctic fish to survive at temperatures close to freezing. This natural anti-freeze was discovered in the 1950s. The physical peculiarity is the starting point for the diversification of the notothenioidei. Today the animals contribute significantly to the diversity of the Antarctic marine life, and they serve as food for predators such as penguins, toothed whales and seals.

Obviously, further adaptations have made the fish particularly suitable for the living conditions near the Antarctic ice sheet. This includes, for example, the varying buoyancy of the fish without swim bladders. Closely related species can therefore inhabit a wide variety of marine regions down to the deep sea. The fish thus conquered new ecological niches, while potential competitors disappeared forever in the icy environment. Today's diversity is therefore not just the result of a single key innovation, the emergence of the anti-frost protein is just one of many factors for the amazing diversification of the parent species.

Systematics

Phylogenetic systematics of the Antarctic fish according to Near et al. 2012, 2015 and 2018:
  Antarctic fish  

 Percophidae


   

 Ice fish (Bovichtidae)


   

 Catadromous ice fish (Pseudaphritidae)


   

 Patagonian slimy fish (Eleginopsidae)


  Cryonotothenioidea  


 Antarctic silverfish ( Pleuragramma antarctica ) (Nototheniinae)


   


 Aethotaxis mitopteryx (Nototheniinae)


   

 Dissostichus (Nototheniinae)



   

 Trematominae (Nototheniinae)




   

 Gobionotothen (Nototheniinae)


   

 Notothenia (Nototheniinae)


   


 Antarctic predatory fish (Harpagiferidae)


   

 Artedidraconidae



   

 Crocodile ice fish (Channichthyidae)


   

 Antarctic  dragonfish (Bathydraconidae)











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For a long time the closest relatives and sister group of the Antarctic fish were the eel-mother-like (zoarcoidei), which mostly inhabit the northern cold seas, or the dragon fish (trachinoidei), which are no longer a valid taxon in modern systematics. According to a recent study, the Antarctic fish are the sister group of a large clade of perch-like fish. a. Bullhead relatives , eel-mother-like, stickleback-like , gurnard and rock perch include.

The Antarctic fish are divided into nine families, about 45 genera and over 150 species. Three families, the Percophidae , the Eleginopsidae and the Pseudaphritidae , are monotypical , another, the Nototheniidae, are not monophyletic .

With the exception of one species of ice fish, the first four families do not live in the Southern Ocean , but in the southern hemisphere, the rest form an Antarctic clade, the Cryonotothenioidea. Of the 49 species of Antarctic cod, 33 are Antarctic and 16 are non-Antarctic. All species in the last four families are Antarctic.

Giant Antarctic Cod ( Dissostichus mawsoni )

literature

  • Joseph S. Nelson : Fishes of the World. 4th edition. John Wiley & Sons, Hoboken NJ et al. 2006, ISBN 0-471-25031-7 .
  • JT Eastman, AL DeVries: The Antarctic Fish . in: Biology of the Seas . Spektrum Akad. Verl., 1991, ISBN 3-89330-753-2 .
  • JT Eastman, RR Eakin: An updated species list for notothenioid fish (Perciformes; Notothenioidei), with comments on Antarctic species . PDF .
  • TJ Near, JJ Pesavento, Chi-Hing C. Cheng: Phylogenetic investigations of Antarctic notothenioid fishes (Perciformes: Notothenioidei) using complete gene sequences of the mitochondrial encoded 16S rRNA . PDF .
  • Thomas J. Near, Alex Dornburg, Kristen L. Kuhn, Joseph T. Eastman, Jillian N. Pennington, Tomaso Patarnello, Lorenzo Zane, Daniel A. Fernández, Christopher D. Jones: Ancient climate change, antifreeze, and the evolutionary diversification of Antarctic fishes. PNAS , 2012 doi : 10.1073 / pnas.1115169109 .

Individual evidence

  1. ↑ Thomas J. Near, Alex Dornburg, Kristen L. Kuhn, Joseph T. Eastman, Jillian N. Pennington, Tomaso Patarnello, Lorenzo Zane, Daniel A. Fernández & Christopher D. Jones: Ancient climate change, antifreeze, and the evolutionary diversification of Antarctic fishes PNAS, February 28, 2012, vol. 109 no.9, doi: 10.1073 / pnas.1115169109
  2. ↑ a b c d Thomas J. Near, Alex Dornburg, Richard C. Harrington, Claudio Oliveira, Theodore W. Pietsch, Christine E. Thacker, Takashi P. Satoh, Eri Katayama, Peter C. Wainwright: Identification of the notothenioid sister lineage illuminates the biogeographic history of an Antarctic adaptive radiation. June 2015, Doi: 10.1186 / s12862-015-0362-9
  3. ↑ Near, TJ, MacGuigan, DJ, Parker, E., Struthers, CD, Jones, CD & Dornburg, A .: Phylogenetic analysis of Antarctic notothenioids illuminates the utility of RADseq for resolving Cenozoic adaptive radiations. Molecular Phylogenetics and Evolution. September 2018. doi: 10.1016 / j.ympev.2018.09.001
  4. ↑ Guido di Prisco, Joseph T. Eastman, Daniela Giordano, Elio Parisi, Cinzia Verde: Biogeography and adaptation of Notothenioid fish: Hemoglobin function and globin-gene evolution. Gene 398 (2007) pp 143-155.

Web links

Commons : Notothenioidei  - collection of images, videos and audio files