Stomiiformes

Cyclothone microdon

The Maulstachler ( Stomiiformes ( = Stomiatiformes Rosen, 1973)), also known as loudmouths, are an order of bony fishes ( Osteichthyes ). There are inhabitants of the deep sea, especially tropical or temperate marine regions.

Features

Most species are black or silvery colored, and all, except one, have light organs. Their swim bladder is usually reduced, the skeleton of light and the body has a high content of lipids. Most species are small and do not even reach a length of 10 cm. The smallest species are 1.5 cm long, the biggest half a meter. Although William Beebe reported from foot Stach learning of six feet ( about 1.8 meters ) in length, which he described as Bathysphaera intacta, but specimens of this size have never been caught.

Many have a bizarre appearance, light organs at various points of the body, and huge fangs in large, deeply divided and far-reaching behind the eyes mouths. The color of the Maulstachler is usually dark brown or black, bristle types of mouths ( Gonostomatidae ) are often silvery. The light-emitting organs are unique among all Teleostei and having a flat wall of connective tissue cells are embedded in the Guaninplättchen and which are covered on the outside by a pigment layer. The Guaninplättchen act as reflectors. In the light organs, the Photocyten, are light -producing cells, which have a very well-developed endoplasmic reticulum, and glandular cells that may have a function as a filter. Maulstachler generate their own luciferin. The lighting is not so here produced by bacteria, such as in the planthoppers ( Anomalopidae ). Overall, three types of light organs can be distinguished. When alpha type, the light organs are arranged in rows that run perpendicular to the longitudinal axis of the light organs. When the beta type the luminous organs are arranged around a central cavity, which sometimes has an opening to the outside. The light-emitting members of the gamma - type, are arranged in a circle around a center. Light organs which derive their luminosity by bacteria, there are also numerous species at six other teleost groups, but their morphology is always different than those of Maulstachler.

The teeth can be folded backwards. They rotate about an axis at the front base of the tooth. There they are connected to the base via mineralized connective tissue at the back only by connective tissue. Both maxilla and premaxilla are dentate. Often the Maulstachler have a Bartel on the lower jaw. The eyes are often prominent telescopic eyes, the larvae often sitting on stems. Many species do not shed, they are present, then there are circular scales that fall off easily. The pectoral fins and dorsal fin and adipose fin absent in many species. Are pectoral fins are present, they put on deep, the ventral fins have four to nine fin rays. The swim bladder is without ductus pneumaticus or missing entirely. If it is present, it is located at the rear end of a rete mirabile, a network of fine arteries that serve the gas exchange. In almost all other Teleostei, except for some slime head and spine Fishy, the rete mirabile is at the front end of the swim bladder or placed in the center. The number of Branchiostegalstrahlen is 5 to 24, which are located behind a greatly enlarged, some joints with the ventral Hypohyalen, another bone of Branchiostegalapparats.

Way of life

In most cases life Maulstachler meso and bathypelagic so at depths of 200 to 4000 meters. Many among the most common marine fish. In particular, the genera Cyclothone from the family of bristle mouths and Vinciguerria from the family of fluorescent fish are mentioned again and again as the individual- most species of fish, and many ichthyologists assume that they represent more single copies than any other vertebrate species on Earth, and that their total mass is greater than those of all other species of fish. Other Maulstachlerarten and genera are apparently rare and were only slightly caught ( Sonoda, Rhadinesthes Decimus, Araiophos eastropas ). Maulstachler are carnivorous and feed mainly on crustaceans and smaller fish. They themselves are an important source of food for marine predators and marine mammals.

Outer systematics

The Maulstachler are usually as a basal group assigned to the Neoteleostei, the modern bony fishes. However, recent studies come to the conclusion that they are outside of Neoteleostei and the sister group of the smelt -like ( Osmeriformes ) are a teleost order whose members live primarily in cool and temperate regions in brackish and fresh water.

The following cladogram shows the systematic position of the Maulstachler as a sister group of the smelt -like:

Salamander fish ( Lepidogalaxias salamandroides )

Lachsartige ( Salmoniformes )

Pike -like ( Esociformes )

Galaxies ( Galaxiiformes )

Gold Lachsartige ( Argentiniformes )

Stint behaved ( Osmeriformes )

Maulstachler ( Stomiiformes )

Tiefseequappenartige ( Ateleopodiformes )

Eurypterygii

Inside systematics

The internal classification of Maulstachler is still very uncertain, especially the glowing fish ( Phosichthyidae ) are considered paraphyletic. The American ichthyologist Joseph S. Nelson is in his standard work on fish systematics Fishes of the World in two sub-orders and five families. Other sources such as FishBase, register only four families (not the Diplophidae whose genera are then counted to Gonostomatidae ). Altogether there are about 53 genera and 420 species:

  • Family Diplophidae
  • Subordination Gonostomatoidei Family bristle mouths ( Gonostomatidae )
  • Family deepwater Beilfische ( Sternoptychidae ) Subfamily Maurolicinae
  • Subfamily Sternoptychinae
  • Family glowing fish ( Phosichthyidae )
  • Family Barten dragon fish ( Stomiidae ) Subfamily Astronesthinae
  • Subfamily shed dragon fish ( Stomiinae )
  • Subfamily Viper fish ( Chauliodontinae )
  • Subfamily shed lots of dragon fish ( Melanostomiinae )
  • Subfamily Black dragon fish ( Idiacanthinae )
  • Subfamily Malacosteinae

According to current findings are at least several light fish species - just like the Viper Fish - closer related to the deep-sea Beilfischen than as shown here, with the ( remaining ) Barten dragon fish. This is also specified here divided into suborders conduct; after spin-off of the luminous fish and fish Viper would then possibly monophyletic Phosichthyoidei no longer the appropriate name.

Fossil record

The secure fossil record of the order dates back to the Eocene. Also from the Miocene are known numerous Maulstachlerfossilien. In part they are still assigned to existing genera. The Cretaceous genus Idrissa could be the oldest known Maulstachlerfossil. This assignment is problematic and controversial.

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