Naked-back knifefish

The naked-back knifefishes are a family (Gymnotidae) of knifefishes found only in fresh waters of Central America and South America. All have organs adapted to electroreception. The family has about 43 valid species in two genera.[1] These fish are nocturnal and mostly occur in quiet waters from deep rivers to swamps. In strongly flowing waters, they may bury themselves.[2]

Naked-back knifefishes
Electric eel, Electrophorus electricus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gymnotiformes
Suborder: Gymnotoidei
Family: Gymnotidae
Genera

Electrophorus
Gymnotus

Physical characteristics

Like the other gymnotiforms, gymnotids have classic knifefish bodies. The body is long and eel-like, the dorsal fin and pelvic fins are absent, and the anal fin is extremely long and used for movement.[2]

The sole member of Electrophorus is the electric eel, which produces both strong (up to 600 volts) and weak (<1 V) electric discharges, for use in predation and communication/navigation, respectively. The electric eel is the largest of the gymnotiform fishes, growing up to more than 2 m (6.6 ft) length. Species of Gymnotus range from about 10–100 cm (0.3–3.3 ft) in total length.[3][4]

These knife fishes also use electricity to assist in their movement and navigation in the water due to their limited vision.[5]

Genera

According to FishBase, there are 43 species in two genera:[1]

Historically, Electrophorus was in a separate family Electrophoridae and ITIS continues to do this,[6] but this is contradicted by available evidence and not followed by other authorities.[1][4][7][8]

References
  1. "FAMILY Details for Gymnotidae - Naked-back knifefishes". www.fishbase.de. Retrieved 2021-12-22.
  2. Froese, Rainer, and Daniel Pauly, eds. (2007). "Gymnotidae" in FishBase. April 2007 version.
  3. Nelson, Joseph, S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7.{{cite book}}: CS1 maint: multiple names: authors list (link)
  4. van der Sleen, P.; J.S. Albert, eds. (2017). Field Guide to the Fishes of the Amazon, Orinoco, and Guianas. Princeton University Press. pp. 330–334. ISBN 978-0691170749.
  5. "Predators: The knifefishes | Features | Practical Fishkeeping". Archived from the original on 2013-06-03. Retrieved 2012-03-16.
  6. "Electrophoridae". ITIS. Retrieved 2016-10-11.
  7. Ferraris Jr, C.J.; C.D. de Santana; R.P. Vari (2017). "Checklist of Gymnotiformes (Osteichthyes: Ostariophysi) and catalogue of primary types". Neotrop. Ichthyol. 15 (1). doi:10.1590/1982-0224-20160067.
  8. Eschmeyer, W.N.; R. Fricke; R. van der Laan (12 May 2018). "Catalog of Fishes". California Academy of Sciences. Retrieved 12 May 2018.
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