Naked-back knifefish
| Naked-back knifefish | |
|---|---|
| |
| Banded knifefish (Gymnotus carapo) | |
| |
| Electric eel, Electrophorus electricus | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Gymnotiformes |
| Family: | Gymnotidae Rafinesque, 1815[1] |
| Genera | |
|
see text | |
The naked-back knifefishes are a family, the Gymnotidae, of ray-finned fishes belonging to the order Gymnotiformes. The fishes in this family are 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. These fish are nocturnal and mostly occur in quiet waters from deep rivers to swamps. In strongly flowing waters, they may bury themselves.[2]
Physical characteristics
[edit]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 electric eels of the genus Electrophorus are the largest species, and they are capable of generating both strong (up to 600 volts) and weak (<1 V) electric discharges, for use in predation and communication/navigation, respectively. The electric eel (E. electricus) 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
[edit]According to Eschmeyer's Catalog of Fishes, there are 43 species in two genera, each in a monotypic subfamily:[6]
- Subfamily Electrophorinae Gill, 1872
- Genus Electrophorus Gill, 1864 (3 species)
- Subfamily Gymnotinae Rafinesque, 1815
Historically, Electrophorus was in a separate family Electrophoridae and ITIS continues to do this,[7] but this is contradicted by available evidence and not followed by other authorities.[2][4][8][6]
References
[edit]- ^ Richard van der Laan; William N. Eschmeyer & Ronald Fricke (2014). "Family-group names of recent fishes". Zootaxa. 3882 (2): 1–230. doi:10.11646/zootaxa.3882.1.1. PMID 25543675.
- ^ a b c Froese, Rainer; Pauly, Daniel (eds.). "Family Gymnotidae". FishBase. April 2007 version.
- ^ Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7.
- ^ a b 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.
- ^ "Predators: The knifefishes | Features | Practical Fishkeeping". Practical Fishkeeping. Retrieved 2012-03-16.
- ^ a b Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Genera in the family Gymnotidae". Catalog of Fishes. California Academy of Sciences. Retrieved 28 May 2025.
- ^ "Electrophoridae". ITIS. Retrieved 2016-10-11.
- ^ 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.
