New World knife fish

New World knife fish
Green knife fish ( Eigenmannia virescens )
Systematics
Subclass : Real bony fish (Teleostei) Overcohort : Clupeocephala Cohort : Otomorpha Sub-cohort : Ostariophysi Otophysa Order : New World knife fish
Scientific name
Gymnotiformes
Berg , 1940

The New World knife fish (Gymnotiformes), also called knife eel-like or Nacktaale , are an order of the real bony fish (Teleostei). They occur in the fresh waters of South and Central America .

features

The animals have an elongated, eel-like body that can be flattened on the side or round in cross-section. It is named after its extra-long anal fin with more than 150 fin rays, which, with its wave-like movements, serves as a forward and backward drive and gives them their knife-like body shape. Ventral fins, pelvic girdle and dorsal fin are missing. A caudal fin is also missing or only very small. The maxillary is toothless. The anus is located in the front half of the body. Gymnotiformes give in case of danger no shock substance from.

Way of life

All species of the New World knife fish are active at night or at dawn and have an electrical organ for orientation. In the largest species, the electric eels ( Electrophorus sp.), Which can grow to a maximum of two meters in length , the voltage generated is so high that they can kill their prey with it. Most species are specialized insect larvae eaters that occur in very different biotopes. Almost all knife eels do not care for their brood.

Catfish such as the tiger spatula are close relatives of the New World knife fish.

External system

The gymnotiformes among the Ostariophysi , which also include Cyprinids (Cypriniformes), the catfish-like (Siluriformes), and especially from the fighting dogs known Characins (Characiformes) belong. Their phylogenetic relationships are shown in the following cladogram :

Otomorpha	Clupei    Herring-like (Clupeiformes)       Alepocephali    Alepocephaliformes   Ostariophysi     Anotophysa    Sandfish (Gonorynchiformes)   Otophysa     Cypriniphysae    Carp-like (Cypriniformes)       Characiphysae    Tetras (Characiformes)   Siluriphysae    New World Knifefish (Gymnotiformes)      Catfish (Siluriformes)

Internal system

There are two suborders, two superfamilies, five families, 30 genera and about 160 species.

• Subordination Gymnotoidei; Body cylindrical, 31 to 51 vertebrae in front of the caudal spine (more than 100 in the electric eel).
  • Knife eels family (Gymnotidae)
• Subordination Sternopygoidei; Body mostly laterally flattened (rarely also cylindrical), 12 to 26 vertebrae in front of the caudal spine.
  • Superfamily Rhamphichthyoidea
    • Family Sand knifefish (Rhamphichthyidae)
    • Small knifefish family (Hypopomidae)
  • Superfamily Apteronotoidea
    • Family glass knife fish (Sternopygidae)
    • Family tail fin knifefish (Apteronotidae)

literature

• Ferraris Jr., CJ, de Santana, CD & Vari, RP (2017): Checklist of Gymnotiformes (Osteichthyes: Ostariophysi) and catalog of primary types. Neotropical Ichthyology, 15 (1): Mar 30, 2017.
• Alfred Kaestner : Textbook of special zoology . 2. Volume: Dietrich Starck (Ed.): Vertebrates. Part 2: Kurt Fiedler: Fish. Gustav Fischer Verlag, Jena 1991, ISBN 3-334-00339-6 .
• Frank Kirschbaum: Reproductive strategies in South American knife fish, Gymnotiformes. In: Aquaristik-Fachmagazin & Aquarium heute. Vol. 34, No. 6 = No. 168, 2002, ISSN  1437-4854 , pp. 38-43.
• Joseph S. Nelson : Fishes of the World. 4th edition. John Wiley & Sons, New York NY 2006, ISBN 0-471-25031-7 .
• Günther Sterba : The world's freshwater fish. 2nd Edition. Urania-Verlag, Leipzig et al. 1990, ISBN 3-332-00109-4 .

Web links

Commons : New World Knifefish  - Collection of images, videos and audio files

• New World Knifefish on Fishbase.org (English)
• JS Albert, JG Lundberg: Gymnotiformes. The Neotropical Electric Eels and Knifefishes. The Tree of Life Web Project