African knifefish

In 1950, Hans Lissmann noticed that the fish could swim equally well forwards or backwards, clearly relying on a sense other than vision.Its conservation status is globally of least concern, but it faces local threats in West Africa from human activities including overfishing and pollution.[5] elephantfishes African knifefish The earliest known fossil remains of Gymnarchus are from the Middle Eocene (Lutetian) of Libya, although its lineage likely diverged from the Mormyridae during the Late Cretaceous.Instead, it navigates and hunts smaller fish using a weak electric field, as demonstrated by the zoologist Hans Lissmann in 1950.[17] Like the related elephantfish, which hunts the same way, it possesses an unusually large brain, which allows it to interpret the electrical signals.[18] The electric organ is derived from striated muscle in a developmental process which makes the filaments thicker, loses the striations, and creates positive and negative ends of the constituent electroplates.Eigenmannia, a South American electric fish, processes sensory information extremely similar to G. niloticus and likewise employs a jamming avoidance response, evolved convergently.Adults catch a variety of small prey including aquatic insects (28%) and fish (27%), with smaller quantities of copepods, shrimps, crabs,[21] frogs, and snails.[24] The sex ratio, biased in favour of males, may help to guarantee that the small number of large eggs are fertilised.[9] It is found in lakes and rivers in the Nile, Turkana, Chad, Niger, Volta, Senegal, and Gambia basins.[9] The decline of this species in Nigeria is thought to be due to the destruction of habitat, unauthorized and irregular fishing practices, overfishing, and human activities near the river.[9] A specific threat is that the young are often captured along with their parent; since they die in captivity, the population is in danger from this unsustainable fishing approach.[25] With good taste and large body size with a lot of meat, Gymnarchus niloticus is a highly valued food source in several West African countries.
Gymnarchus swims with its back straight, propelling itself with its dorsal fin, not its tail. This allows it to generate a steady electric field to navigate and to detect its prey.
PreꞒConservation statusLeast ConcernIUCN 3.1Scientific classificationEukaryotaAnimaliaChordataActinopterygiiOsteoglossiformesBleekerCuvierBinomial nameelectric fishonly speciesfamilypelvicanal finstail findorsal finlocate its preyHans LissmannelectroreceptionGeorges CuviermonospecificPieter Bleekersynonymaccidentally createdHenri Émile SauvageRiver NilesisterMormyridaeMormyroideaelephantfishesGymnarchidaeAfrican knifefishelectric organMiddle EoceneLutetianLate CretaceousOsteoglossomorphawhite undersidecycloid scalesanguilliformcaudal finpectoral finsallometrickaryotypechromosomesgenerate a steady electric fieldelectroreception and electrogenesiselephantfishelectric fieldelectric organstriated musclejamming avoidance responseEigenmanniaevolved convergentlypredatorydecapodcopepodsis bottom-dwellinglives in fresh watertestisflagellumamoebafloodplainsEchinochloa pyramidalisPollimyrussex ratioendemicTurkanaSenegalGambiaIUCN Red Listendangered speciesdestruction of habitatoverfishingeffluentsclimate changeaquacultureethically sourcedbiomimeticEntsua-Mensah, M.IUCN Red List of Threatened SpeciesFroese, RainerFishBaseBullock, Theodore H.Brain Research ReviewsBibcodeAcademic PressAlexander, R. McNeillJournal of Experimental BiologyAmpullae of LorenziniKnollenorganGymnotiformesElectrophorusRajiformesMalapteruridaeTorpediniformesUranoscopidaeHistory of bioelectricityLateral lineMagnetoreceptionWikidataWikispeciesiNaturalistOpen Tree of LifePaleobiology Database