Naked-back knifefish

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iNaked-back knifefishes

Electric eel, Electrophorus electricus

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Gymnotiformes
Family:	Gymnotidae

Genera

Electrophorus
Gymnotus
See text for species.

The naked-back knifefishes are a family (Gymnotidae) of knifefishes that do not have a dorsal fin. They are found only in fresh waters of Central America and South America. All have organs adapted to the exploitation of bioelectricity.

The family has at least 33 species in two genera. The sole member of Electrophorus is the electric eel, which produces both strong (up to 600 V) and weak (<1 V) electric discharges, for use in predation and communication/navigation, respectively. The electric eel is the largest of the gymnotifomm fishes, growing up to more than 2 m (7 feet) in length.

Gymnotus is the among the most species-rich group of knifefishes found in the Amazon. Some Gymnotus species live in the leaf litter and root tangles of river banks. Other species are specialized to live on floodplains within the rootmats of floating meadows. Several species are broadl adapted to live in both of these habitats. Gymnotus are nocturnal predators feeding on insects, crustaceans, and other fish. They generate weak electric fields used in locating objects, and also for communication in which the males court females using stereotyped electrical "songs".

[edit] Species

There are 33 species in two genera:

Genus Electrophorus
- Electric eel, Electrophorus electricus (Linnaeus, 1766).
Genus Gymnotus
- Gymnotus anguillaris Hoedeman, 1962.
- Gymnotus arapaima Albert & Crampton, 2001.
- Gymnotus ardilai Maldonado-Ocampo & Albert, 2004.
- Gymnotus bahianus Campos-da-Paz & Costa, 1996.
- Banded knifefish, Gymnotus carapo Linnaeus, 1758.
- Gymnotus cataniapo Mago-Leccia, 1994.
- Gymnotus choco Albert, Crampton & Maldonado, 2003.
- Gymnotus coatesi La Monte, 1935.
- Gymnotus coropinae Hoedeman, 1962.
- Gymnotus curupira Crampton, Thorsen & Albert, 2005.
- Gymnotus cylindricus La Monte, 1935.
- Gymnotus diamantinensis Campos-da-Paz, 2002.
- Gymnotus esmeraldas Albert & Crampton, 2003.
- Gymnotus henni Albert, Crampton & Maldonado, 2003.
- Gymnotus inaequilabiatus (Valenciennes, 1842).
- Gymnotus javari Albert, Crampton & Hagedorn, 2003.
- Gymnotus jonasi Albert & Crampton, 2001.
- Spotted knifefish, Gymnotus maculosus Albert & Miller, 1995.
- Gymnotus mamiraua Albert & Crampton, 2001.
- Gymnotus melanopleura Albert & Crampton, 2001.
- Gymnotus obscurus Crampton, Thorsen & Albert, 2005.
- Gymnotus onca Albert & Crampton, 2001.
- Gymnotus panamensis Albert & Crampton, 2003.
- Gymnotus pantanal Fernandes, Albert, Daniel-Silva, Lopes, Crampton & Almeida-Toledo, 2005.
- Gymnotus pantherinus (Steindachner, 1908).
- Gymnotus paraguensis Albert & Crampton, 2003.
- Gymnotus pedanopterus Mago-Leccia, 1994.
- Gymnotus stenoleucus Mago-Leccia, 1994.
- Gymnotus sylvius Albert & Fernandes-Matioli, 1999.
- Gymnotus tigre Albert & Crampton, 2003.
- Gymnotus ucamara Crampton, Lovejoy & Albert, 2003.
- Gymnotus varzea Crampton, Thorsen & Albert, 2005.