Gadiformes
Cod (Gadus morhua )
The cod -like ( gadiformes ) are one of the genuine bony fish ( Teleostei ) who live almost exclusively in the sea. They are mainly found in the seas of the northern hemisphere. Distribution area is the North Atlantic, but also found in southern waters to the Southern Ocean cods. Many species live in the deep sea to depths of 6,000 meters. In tropical and subtropical coastal waters they are rare. The only cod -like freshwater inhabitants are the burbot ( Lota lota ) and the Atlantic Tomcod ( Microgadus Tomcod ), who is actually a resident of the north-western Atlantic, from which it but in two lakes (Deer Lake, Newfoundland, Lac Saint- Jean, Québec) freshwater populations out there that have been cut off from the sea.
- 7.1 Literature
- 7.2 Notes and references
- 7.3 External links
Features
Cods are elongated, usually spindle- like shaped fish. You have only upper ribs, no bones ( Bindegewebsverknöcherungen who have no contact with the spine and between the muscle segments ) and usually no real hard rays in the fins. Only the most Grenadiers ( Macrouridae ) have a hard, serrated, second dorsal spine in the dorsal fin. The sole presence of soft rays is probably secondary. Dorsal fin and anal fin are usually very elongated, sometimes grown together with the ever- symmetrical tail fin to a hem. The dorsal fin is often divided into two or three parts, the anal fin consists of one to two parts. The caudal fin is currently completing, is slightly forked, but lacking in many forms, runs the body into a rat -like, pointed tail. The pelvic fins are often missing or if they are present, prior to or just below the pectoral fins (or, at the Macrouridae, close behind ). They are often reduced to filamentary yarns. The pelvic bones are loosely connected via a ligament with the shoulder girdle and behind the symphysis. The caudal fin is homocerk and has stunted Hypuralia.
Cods are Physoclisten, that is, their swim bladder is closed, the gas exchange takes place via blood vessels. The swim bladder is also used as a resonance chamber for volume production. For ground-dwelling species, it is reduced. The saccule is very large. In the skull basisphenoid, Myodom, Mesocoracoid and Orbitosphenoid missing. Many cods have chin barbels. The upper jaw edge is usually formed only by the premaxilla, which is strongly dentate. The gill opening is very large. The number of Branchiostegalstrahlen is six to eight. The scales are usually roundhouse, rare comb scales. The otoliths ( "ear stones " ) of the fish are relatively uniform and are only more specialized at the fork cod.
Way of life
All Gadiformes live in flocks 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 migrations. Many cods produce an unusually high number of eggs. Females of cod spawning place in a period of up to nine million eggs. Eggs and larvae are pelagic.
Outer systematics
The cod -like are according to the latest research, the sister group of Stylephorus chordatus. From this except their closest relatives are the Peter Fishy ( Zeiformes ).
The following cladogram shows the systematic position of the cod -like:
Tiefseequappenartige ( Ateleopodiformes )
Eidechsenfisch Related ( Aulopiformes )
Lantern Fishy ( Myctophiformes )
Gloss Fishy ( Lampridacea )
Perch Lachsartige ( Percopsaria )
Dories ( Zeiformes )
Stylephorus chordatus ( Stylephoriformes )
Cods ( gadiformes )
Bart Fishy ( Polymixiacea )
Mucus -like head ( Beryciformes )
Soldiers and hussars fish ( Holocentriformes )
Related perch ( Percomorphaceae )
Inside systematics
Phylogenetic relationships within the cod -like are controversial and the subject of scientific debate. Previously, the families of the viscera Fishy ( Ophidiiformes ) and partly also the Aalmutterartigen ( Zoarcoidei ) were attributed to order. The following three proposals are presented. The first comes from the American ichthyologists Joseph S. Nelson from his standard work on fish systematics Fishes of the World. The second system was developed by the Japanese ichthyologists Hiromitsu Endo based on 49 morphological characters. Some of the taxa that have the rank of subfamilies in Nelson get here family rank. The third proposal is based on the analysis of mitochondrial and nuclear DNA and differs greatly from Endo morphological kinship analysis from. The basalste family of cod -like here are the Aaldorsche, Endo, however, the deep-sea cod. The Grenadiers are divided into several families and assigned to two different submissions. Only the phylogeny of the crown group of the Gadidae remains the same.
- Fam Aaldorsche ( Muraenolepididae )
- Fam unicorn cod ( Bregmacerotidae )
- Fam Euclichthyidae
- Fam Grenadiers ( Macrouridae ) Unterfam. Bathygadinae
- Unterfam. Macrourinae
- Unterfam. Trachyrincinae
- Unterfam. Macrouroidinae
- Unterfam. Macruroninae
- Unterfam. Merlucciinae
- Unterfam. Steindachneriinae
- Unterfam. Hake ( Phycinae )
- Unterfam. Gaidropsarinae
- Unterfam. Actual cod ( Gadinae )
- Unterfam. Burbot ( Lotinae )
- Unterfam. Frog cod ( Ranicipitinae )
Subordination Melanonoidei
- Fam deep-sea cod ( Melanonidae )
Subordination Macrouroidei
- Grenadiers ( Macrouridae ) Unterfam. Bathygadinae
- Unterfam. Macrourinae
- Unterfam. Trachyrincinae
- Unterfam. Macrouroidinae
Subordination Gadoidei
- Fam Euclichthyidae
- Fam deep sea cods ( Moridae )
- Fam Macruronidae
- Fam hake ( Merlucciidae )
- Fam frog cod ( Ranicipitidae )
- Fam unicorn cod ( Bregmacerotidae )
- Fam Aaldorsche ( Muraenolepididae )
- Fam Gadidae Unterfam. Hake ( Phycinae )
- Unterfam. Gaidropsarinae
- Unterfam. Burbot ( Lotinae )
- Unterfam. Actual cod ( Gadinae )
Subordination Muraenolepidoidei
- Fam Aaldorsche ( Muraenolepididae )
Subordination Macrouroidei
- Fam Macrouridae
- Fam Bathygadinae
- Fam Macruronidae
- Fam Steindachneriidae
Subordination Gadoidei
- Fam Trachyrincidae Unterfam. Trachyrincinae
- Unterfam. Macrouroidinae
- Unterfam. Hake ( Phycinae )
- Unterfam. Gaidropsarinae
- Unterfam. Burbot ( Lotinae )
- Unterfam. Actual cod ( Gadinae )
The systematics in the FishBase is largely inspired Nelson to, differs from the latter in that the tadpoles form a separate family, which also includes the types of Gaidropsarinae are provided.
Phylogeny
Cladogram after Hiromitsu Endo:
Deep-sea cod ( Melanonidae )
Macrouroidinae
Trachyrincinae
Macrourinae
Bathygadinae
Steindachneriidae
Euclichthyidae
Deep-sea cod ( Moridae )
Macruronidae
Hake ( Merlucciidae )
Frog cod ( Ranicipitidae )
Unicorn cod ( Bregmacerotidae )
Aaldorsche ( Muraenolepididae )
Gaidropsarinae
Hake ( Phycinae )
Burbot ( Lotinae )
Actual cod ( Gadinae )
Cladogram after Adela Roa - Varon & Guillermo Ortí:
Aaldorsche ( Muraenolepididae )
Macrouridae
Bathygadinae
Macruronidae
Steindachneriidae
Trachyrincinae
Macrouroidinae
Deep-sea cod ( Moridae )
Hake ( Merlucciidae )
Deep-sea cod ( Melanonidae )
Euclichthyidae
Actual cod ( Gadinae )
Burbot ( Lotinae )
Gaidropsarinae
Hake ( Phycinae )
Frog cod ( Ranicipitidae )
Unicorn cod ( Bregmacerotidae )
Phylogeny
The cod -like are supposed to have emerged at the end of the Cretaceous period in the tropical Tethys. After the establishment of connections to the northern seas they spread out in the new living room and made a quick Adaptive radiation through. First secure evidence by ear stones are available from the Eocene. From this period also fossils of unicorn cod in Europe, West Asia and North Africa originate. In the Oligocene of the North Caucasus, the Carpathians, Switzerland, Eastern France, Australia and New Zealand were found, the first cod, for example Paleogadus and Pseudoraniceps and hake Merluccis errans. Deepwater hake of the genus Gadella are from the Pliocene of Fiume Marecchia ( Northern Italy ) are known. In the Pliocene, they should have also colonized the Pacific Ocean, the Southern Ocean until the beginning of the Ice Age.
Use
To the order are economically very important food fish, more than 1/4 of the world's commercially caught marine fish belonging to the cod -like. Economically particularly significant is the cod family ( Gadidae ), to which the cod, haddock, saithe and ling are the.