Cod-like
| Cod-like | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cod ( Gadus morhua ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Gadiformes | ||||||||||||
| Goodrich , 1909 |
The cod-like (Gadiformes) are an order of the real bony fish (Teleostei) that live almost exclusively in the sea. They are mainly found in the seas of the northern hemisphere. The main area of distribution is the North Atlantic, but cod-like species can also be found in southern waters up to the Southern Ocean . Many species also live in the deep sea to depths of 6000 meters. They are rare in tropical and subtropical coastal waters. The only freshwater cod-like inhabitants are the burbot ( Lota lota ) and the Atlantic tomcod ( Microgadus tomcod ), which is actually an inhabitant of the north-western Atlantic, but of which it is divided into two lakes ( Deer Lake , Newfoundland; Lac Saint-Jean , Québec) Freshwater populations that have been cut off from the sea.
features
.jpg)
Cod-like are elongated, usually spindle-shaped fish. They only have upper ribs, no bones (connective tissue ossifications that have no contact with the spine and lie between the muscle segments ) and usually no real hard rays in the fins. Only most grenadier fish (Macrouridae) have a hard, serrated, second fin ray in the dorsal fin . The mere presence of soft rays is likely secondary. The dorsal fin and anal fin are usually very elongated, sometimes also grown together with the always symmetrical caudal fin to form a hem. The dorsal fin is often divided into two or three parts, the anal fin consists of one or two parts. The caudal fin ends straight, is slightly forked, but is absent in many forms, the body of which ends in a rat-like, pointed tail. The pelvic fins are often absent or, if they are present, are in front of or directly below the pectoral fins (or, in the Macrouridae, just behind). They are often reduced to filament-like threads. The pelvic bones are loosely connected to the shoulder girdle via a ligament and lie behind its symphysis . The caudal fin is homocerk and has stunted hypuralia .
Cod-like are physoclists , i. H. their swim bladder is closed, and gas is exchanged through blood vessels. The swim bladder is also used as a resonance body to generate sounds. It is reduced in soil species. The saccule is very large. The base phenoid , myodoma , mesocoracoid and orbitosphenoid are absent in the skull. Many codfish have chin beards . The upper jaw margin is usually only formed by the premaxillary , which is strongly dentate. The gill opening is very large. The number of Branchiostegal rays is six to eight. The scales are usually round scales , more rarely comb scales. The otoliths ("ear stones") of the fish are relatively uniform and are only more specialized in the forked cod.
Way of life
All cod-like fish live in schools as predatory fish in the open water or on the ground. In order to follow their food animals or to get to the spawning grounds, they undertake long walks. Many cod species produce exceptionally high numbers of eggs. Cod females lay up to nine million eggs in one spawning period. Eggs and larvae are pelagic .
External system
According to current research, the cod-like are the sister group of Stylephorus chordatus . Apart from this, their closest relatives are the Johns fish-like (Zeiformes).
The following cladogram shows the systematic position of the cod-like species:
| Neoteleostei |
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
Internal system
The relationships within the cod-like species are controversial and the subject of scientific discussions. In the past, the families of the intestinal fish-like (Ophidiiformes) and partly also the eel-mother-like (Zoarcoidei) were included in the order. Three suggestions are presented below. The first system was worked out by the Japanese ichthyologist Hiromitsu Endo on the basis of 49 morphological features. The second proposal is based on the analysis of mitochondria - and nuclear - DNA and differs greatly from Endos morphological relationship analysis from. The most basic cod-like family here is the eel cod, while at Endo it is the deep-sea cod. The grenadiers are divided into several families and assigned to two different suborders. The third suggestion comes from a standard work on fish systematics ( Fishes of the World ). The phylogeny of the crown group around the Gadidae is the same in all three classifications.
|
The system in the FishBase database is based on an older version of Fishes of the World , but differs from this in that the tadpoles form an independent family, in which the species of the Gaidropsarinae are also placed.
Phylogeny
|
Hiromitsu Endo cladogram :
|
Cladogram according to Adela Roa-Varón & Guillermo Ortí:
|
Tribal history
The cod-like are said to have originated in the tropical Tethys at the end of the Cretaceous Period . After connections to the northern seas were established, they spread to the new habitat and underwent rapid adaptive radiation . The first reliable evidence from ear stones is from the Eocene . Fossil finds of unicorn cod in Europe, West Asia and North Africa also date from this period . The first cod were found in the Oligocene of the North Caucasus, the Carpathian Mountains, Switzerland, Eastern France, Australia and New Zealand. B. Paleogadus and Pseudoraniceps and the hake Merluccis errans . Deep-sea cod of the genus Gadella are known from the Pliocene of Fiume Marecchia (Northern Italy). In the Pliocene, they are said to have colonized the Pacific , and the Southern Ocean only at the beginning of the Ice Age .
use
The order includes economically very important food fish, more than 1/4 of the marine fish caught commercially worldwide belong to the cod-like species. The cod family (Gadidae), to which the cod , haddock , coalfish and ling belong, is of particular economic importance .
literature
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
- Kurt Fiedler: Textbook of Special Zoology, Volume II, Part 2: Fish . Gustav Fischer Verlag Jena, 1991, ISBN 3-334-00339-6 .
- Arno Hermann Müller: Textbook of paleozoology. Volume III, Vertebrates, Part 1.Page 371, Gustav Fischer Verlag, 1985.
Individual evidence
- ↑ Burbot on Fishbase.org (English)
- ↑ Atlantik-Tomcod on Fishbase.org (English)
- ↑ a b R. Betancur-R., E. Wiley, N. Bailly, A. Acero, M. Miya, G. Lecointre, G. Ortí: Phylogenetic Classification of Bony Fishes - Version 4 (2016)
- ↑ Wei-Jen Chen, Celine Bonillo, Guillaume Lecointre: Repeatability of clades as a criterion of reliability: a case study for molecular phylogeny of Acanthomorpha (Teleostei) with larger number of taxa. Molecular Phylogenetics and Evolution, Volume 26, Number 2, February 2003, pages 262-288 (27), PDF
- ↑ Masaki Miya et al. (2003): Major patterns of higher teleostean phylogenies: a new perspective based on 100 complete mitochondrial DNA sequences. Molecular Phylogenetics and Evolution, Volume 26, Issue 1, January 2003, Pages 121-138 doi : 10.1016 / S1055-7903 (02) 00332-9
- ↑ a b c Hiromitsu Endo: Phylogeny of the Order Gadiformes (Teleostei, Paracanthopterygii). Mem Grad Sch Fish Sci Hokkaido Univ. Vol.49, No.2, pages 75-149 (2002) ISSN 1346-3306
- ↑ a b c Adela Roa-Varón, Guillermo Ortí: Phylogenetic relationships among families of Gadiformes (Teleostei, Paracanthopterygii) based on nuclear and mitochondrial data. Molecular Phylogenetics and Evolution 52 (2009) 688-704, doi : 10.1016 / j.ympev.2009.03.020
- ^ A b Joseph S. Nelson, Terry C. Grande, Mark VH Wilson: Fishes of the World. Wiley, Hoboken, New Jersey, 2016, ISBN 978-1118342336
- ^ Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7
- ↑ Codfish on Fishbase.org (English)
- ^ Karl Albert Frickhinger: Fossil Atlas Fish , Mergus-Verlag, Melle, 1999, ISBN 3-88244-018-X
- ^ Fiedler, page 313.
