Gymnotus

Gymnotus
Gymnotus sp.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gymnotiformes
Family: Gymnotidae
Genus: Gymnotus
Linnaeus, 1758

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 species 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.[1]

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.[2]

Species

There are currently 40 recognized species in this genus:

References

Wikimedia Commons has media related to Gymnotus.
  1. ↑ Nelson, J.S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7.
  2. ↑ Faraday M (1839). "Experimental Researches in Electricity, Fifteenth Series". Philosophical Transactions of the Royal Society 129: 1–12. doi:10.1098/rstl.1839.0002.
  3. ↑ 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. doi:10.1111/j.1095-8649.2012.03219.x.
  4. ↑ 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.
  5. ↑ Cognato, D.P., Richer-de-Forges, M.M., Albert, J.S. & Crampton, W.G.R. (2008). "Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil.". Ichthyologial Explorations of Freshwaters 18 (4): 375–382.
  6. ↑ 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. doi:10.1643/ci-13-054.
  7. ↑ Rangel-Pereira (2012). "Gymnotus interruptus, a new species of electric fish from the Rio de Contas basin, Bahia, Brazil (Teleostei: Gymnotiformes: Gymnotidae)" (PDF). Vertebrate Zoology 62 (3): 363–370.
  8. ↑ Giora J., Malabarba L.R. (2016). "Gymnotus refugio, a new and endangered species of electric fish of the Gymnotus pantherinus species-group from southern Brazil (Gymnotiformes: Gymnotidae)". Zootaxa 4066 (5): 581–590. doi:10.11646/zootaxa.4066.5.6.
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