Eel
European eel (Anguilla anguilla)
The eel-like ( Anguilliformes ) are an order of about 900 species comprehensive serpentine, living almost exclusively in the sea bonefish. They are mostly nocturnal predators.
Dissemination
Most eel-like world live in tropical and subtropical seas, both in shallow coastal waters, coral reefs and in the deep sea. Only the eels ( Anguillidae ) live in freshwater and it solely for procreation into the sea. Two of their species, the European eel (Anguilla anguilla) and American eel (Anguilla rostrata ) are also the only ones whose distribution area far into the temperate climate zone.
Anatomy
All have a snake-like eel-like, elongated body. Their body length ranges from a few centimeters to many Einkieferaalen up to a length of four meters and the Giant Deltamuräne ( Strophidon sathete ). It can be flattened round in cross section or side. Dorsal and anal fins form a continuous Flossensaum. Pelvic fins are at present species no longer exists, can still be seen in some fossil forms, however. The spine can have up to 770 vertebrae, and just completed ( protocerk ). Are mostly scaleless, eel-shaped, in some species there are small round scales under the skin, including the side line is often lacking. Some skull bones are missing, for example, the Posttemporale that many fish the skull to the shoulder girdle connects. On pine merge during metamorphosis some bones ( premaxilla, Ethmo, vomer ), which are still separated during the larval phase. The gill opening is narrow, the gill cover is missing, the gill chamber is supported by the Radii branchiostegi, a skull bone.
System
Protanguillidae
Eels ( Synaphobranchidae )
Eels ( Moringuidae )
Schnepfenaale ( Nemichthyidae )
Stummelschwanzaale ( Cyematidae )
Sawtooth Schnepfenaale ( Serrivomeridae )
Einkieferaale ( Monognathidae )
Pelikanaale ( Eurypharyngidae )
Bag mouths ( Saccopharyngidae )
Eels ( Anguillidae )
Langhalsaale ( Derichthyidae ) Chlopsidae ( partial) conger eels ( congers ) ( partial) Colocongridae
Conger eels ( partial) Entenschnabelaale ( Nettastomatidae )
Conger eels ( partial)
Hechtconger ( Muraenesocidae )
Snake eels ( Ophichthidae )
Chlopsidae ( partial)
Myrocongridae
Moray eels ( Muraenidae )
Protanguillidae
Eels ( Synaphobranchidae )
Heterenchelyidae
Myrocongridae
Moray eels ( Muraenidae )
Chlopsidae
Conger eels ( congers )
Langhalsaale ( Derichthyidae )
Colocongridae
Entenschnabelaale ( Nettastomatidae )
Snake eels ( Ophichthidae )
Hechtconger ( Muraenesocidae )
Eels ( Moringuidae )
Pelikanaalartige ( Saccopharyngoidei )
Schnepfenaale ( Nemichthyidae )
Sawtooth Schnepfenaale ( Serrivomeridae )
Eels ( Anguillidae )
The eel-like are usually divided into three suborders Aalverwandte ( Anguilloidei ) Meeraalverwandte ( Congroidei ) and Muränenverwandte ( Muraenoidei ) and broken down according to author and 15 to 25 families. The submissions, however, have been found to be not monophyletic. The Pelikanaalartigen, however, that were originally performed as a separate order, the Saccopharyngiformes are phylogenetically well within the eel-like and the Teleostei systematics are therefore performed as subordination of the eel-like in a recent audit.
The two cladograms shown on the right show alternative ways of relationships within the eel-like.
The families of the conger eel ( congers ) and the Entenschnabelaale ( Nettastomatidae ) are probably not monophyletic. 2011 has been described with Protanguilla palau a way that together probably represents a basal sister group to all other present eel-like all or with the family of eels.
Fossil record
The first are eel-like fossil from layers of the Upper Cretaceous of Lebanon with the genera Urencelys and Enchelion known. Can Enchelion already a modern family, the conger eel ( congers ) are assigned. Also from the lower Oligocene, there are fossils. The conger Pavelichthys from the northern Caucasus and the Sawtooth Schnepfenaal ( Serrivomeridae ) Proserrivomer from Iran.
An important archaeological site is the North Italian Monte Bolca Formation, which originated from deposits of the Tethys during the Eocene. From her today no family assigned genera Anguilloides, Bolcanguilla, Dalphiaziella, Eomyrophis, Milanangullia, Parangullia, Patavichthys, Proteomycus, Veronagullia and Whitapodus, the conger Bolycus and Voltaconger, and the snake eel Goslinophis have been described.
Of the recent sea eels of the genus Conger there are fossils from the Eocene of Europe, North America and New Zealand. Today eels ( Anguilla) can be detected since the Miocene. Fossils were found among other things in Oehningen on the Upper Rhine (Baden- Württemberg).