Notacanthiformes

Aldrovandia gracilis

The Dornrückenaalartigen ( Notacanthiformes ( Gr. " noton " = back " akantha " = thorn, Lat: . " Format " = shape) ) are an order of marine teleost fish. The world's marine fish live in the deep sea 125-4900 meters, most of 450-2500 meters.

Features

Dornrückenaalartige have an eel-like, elongated, rear tapered body with a long, about half the length of the body engaging the anal fin, which has grown with the rudiments of the tail fin. The caudal skeleton is reduced or absent. If you lose the tail is easily regenerated. The pectoral fins sit relatively high in the body, far below the pelvic fins are supported 7-11 fin rays. The gill membranes are separate. The number of Branchiostegalstrahlen is from 5 to 23 A relatively large air-bladder is provided. The mouth is inferior, the teeth small. The intestine is short, some Pylorusschläuche are available. Some species have light organs. Dornrückenaalartige be 10 cm to 1.2 meters long.

Dornrückenaalartige are only defined by three synapomorphies:

Larvae

The Leptocephaluslarven the Dornrückenaalartigen be longer than the adult animals, a maximum of about two meters. The transparent larvae show more than 300 V-shaped muscle segments. A normal tail fin missing, but you can find a thread-like appendage. The dorsal fin is short and is supported by about ten fin rays. It is located behind the center of the body. Older larvae have small pelvic fins. Some of Leptocephaluslarven Dornrückenaalartigen have been described under the generic name Tilurus and Tiluropsis as separate species.

Outer systematics

Tarpunartige ( Elopiformes )

Bones Fishy ( Albuliformes )

Dornrückenaalartige ( Notacanthiformes )

Eel-shaped ( Anguilliformes )

Tarpunartige ( Elopiformes )

Eel-shaped ( Anguilliformes )

Dornrückenaalartige ( Notacanthoidei )

Bonefish ( Albuloidei )

The systematic position of the Dornrückenaalartigen within the Elopomorpha and their sister group is still controversial. The American ichthyologist Joseph S. Nelson puts them in his standard work on fish systematics Fishes of the World as subordination Notacanthoidei to the order of the bones Fishy ( Albuliformes ). Wiley & Johnson lead on nine synapomorphies for a sister group relationship of Dornrückenaalartigen with the eel-like ( Anguilliformes ). The two cladograms show the alternative possibilities for the systematic position of the Dornrückenaalartigen:

Inside systematics

There are two families, six genera and about 27 species.

• Echsenaale ( Halosauridae )
• Dornrückenaale ( Notacanthidae )