|
''Gymnotus'' is a genus of fish in the order Gymnotiformes found widely in the Neotropics, including 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 broadly 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". Small scales are always present on this fish. The mouth is superior, meaning it is turned upwards. The anal fin terminates at a point near the tip of the tail. Species of ''Gymnotus'' reach up to about 100 cm in length. This is the most widespread genus of the order Gymnotiformes, extending from southern Mexico to Argentina. They also occur in Trinidad. Michael Faraday extensively tested the electrical properties of a ''Gymnotus'' specimen, imported from Suriname. For a span of four months, Faraday carefully and humanely measured the electrical impulses produced by the animal by pressing shaped copper paddles and saddles against the specimen. Through this method, Faraday determined and quantified the direction and magnitude of electric current, and proved the animal's impulses were in fact electrical by observing sparks and deflections on a galvanometer.〔Fifteenth Series, Experimental Researches in Electricity. ''Philosophical Transactions of the Royal Society.'' 1838.〕 ==Species== There are currently 39 recognized species in this genus: * ''Gymnotus anguillaris'' Hoedeman, 1962 * ''Gymnotus arapaima'' J. S. Albert & Crampton, 2001 * ''Gymnotus ardilai'' Maldenado-Ocampo & J. S. Albert, 2004 * ''Gymnotus bahianus'' Campos-da-Paz & W. J. E. M. Costa, 1996 * ''Gymnotus capanema'' Milhomem, Crampton, Pieczarka, Shetka, D. S. Silva & Nagamachi, 2012 〔Milhomem, S.S.R., Crampton, W.G.R., Pieczarka, J.C., Shetka, G.H., Silva, D.S. & Nagamachi, C.Y. (2012): ''Gymnotus capanema'', a new species of electric knife fish (Gymnotiformes, Gymnotidae) from eastern Amazonia, with comments on an unusual karyotype. ''Journal of Fish Biology, 80 (4): 802–815.''〕 * ''Gymnotus capitimaculatus'' Rangel-Pereira, 2014 〔Rangel-Pereira, F.S. (2014): ''Gymnotus capitimaculatus'', a new species of electric fish from rio Jucuruçu basin, northeastern Brazil (Ostariophysi: Gymnotiformes: Gymnotidae). ''Vertebrate Zoology, 64 (2): 169–175''. 〕 * ''Gymnotus carapo'' Linnaeus, 1758 (Banded knifefish) * ''Gymnotus cataniapo'' Mago-Leccia, 1994 * ''Gymnotus chaviro'' Maxime & J. S. Albert, 2009 * ''Gymnotus chimarrao'' Cognato, Richer-de-Forges, J. S. Albert & Crampton, 2008 * ''Gymnotus choco'' J. S. Albert, Crampton & Maldenado-Ocampo, 2003 * ''Gymnotus coatesi'' La Monte, 1935 * ''Gymnotus coropinae'' Hoedeman, 1962 * ''Gymnotus curupira'' Crampton, Thorsen & J. S. Albert, 2005 * ''Gymnotus cylindricus'' La Monte, 1935 * ''Gymnotus diamantinensis'' Campos-da-Paz, 2002 * ''Gymnotus esmeraldas'' J. S. Albert & Crampton, 2003 * ''Gymnotus henni'' J. S. Albert, Crampton & Maldenado-Ocampo, 2003 * ''Gymnotus inaequilabiatus'' Valenciennes, 1842 〔Maxime, E.L. & Albert, J.S. (2014): Redescription of the Tuvirão, ''Gymnotus inaequilabiatus'' Valenciennes, 1839, Using High-Resolution X-ray Computed Tomography. ''Copeia, 2014 (3): 462–472.''〕 * ''Gymnotus interruptus'' Rangel-Pereira, 2012 〔Rangel-Pereira, F.d.S. (2012): (''Gymnotus interruptus'', a new species of electric fish from the Rio de Contas basin, Bahia, Brazil (Teleostei: Gymnotiformes: Gymnotidae). ) ''Vertebrate Zoology, 62 (3): 363–370.''〕 * ''Gymnotus javari'' J. S. Albert, Crampton & Hagedorn, 2003 * ''Gymnotus jonasi'' J. S. Albert & Crampton, 2001 * ''Gymnotus maculosus'' J. S. Albert & R. R. Miller, 1995 (Spotted knifefish) * ''Gymnotus mamiraua'' J. S. Albert & Crampton, 2001 * ''Gymnotus melanopleura'' J. S. Albert & Crampton, 2001 * ''Gymnotus obscurus'' Crampton, Thorsen & J. S. Albert, 2005 * ''Gymnotus omarorum'' Richer-de-Forges, Crampton & J. S. Albert, 2009 * ''Gymnotus onca'' J. S. Albert & Crampton, 2001 * ''Gymnotus panamensis'' J. S. Albert & Crampton, 2003 * ''Gymnotus pantanal'' Fernandes-Matioli, J. S. Albert, Daniel-Silva, C. E. Lopes, Crampton & Almeida-Toledo, 2005 * ''Gymnotus pantherinus'' Steindachner, 1908 * ''Gymnotus paraguensis'' J. S. Albert & Crampton, 2003 * ''Gymnotus pedanopterus'' Mago-Leccia, 1994 * ''Gymnotus stenoleucus'' Mago-Leccia, 1994 * ''Gymnotus sylvius'' J. S. Albert & Fernandes-Matioli, 1999 * ''Gymnotus tigre'' J. S. Albert & Crampton, 2003 * ''Gymnotus tiquie'' Maxime, F. C. T. Lima & J. S. Albert, 2011 * ''Gymnotus ucamara'' Crampton, Lovejoy & J. S. Albert, 2003 * ''Gymnotus varzea'' Crampton, Thorsen & J. S. Albert, 2005 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gymnotus」の詳細全文を読む スポンサード リンク
|