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{{Short description |South American electric fish}} | |||
:''For other meanings, see ].'' | |||
{{pp-semi-indef |small=yes}} | |||
{{Taxobox | |||
{{Speciesbox | |||
| name = | status = LC | |||
| image=Electric-eel.jpg | |||
| status_system = iucn3.1 | |||
| image_caption=Electric eel at the ], United States | |||
| status_ref = <ref>{{cite web|url=http://www.iucnredlist.org/details/167700/0|title=''Electrophorus electricus''|publisher=The IUCN Red List of Endangered Species|accessdate=2014-06-07}}</ref> | |||
| status=LC | |||
| image = Electric-eel.jpg | |||
| status_system=IUCN3.1 | |||
| image_width = 240px | |||
| status_ref=<ref name="iucn status 11 November 2021">{{cite iucn |author=Reis, R. |author2=Lima, F. |date=2009 |title=''Electrophorus electricus'' |volume=2009 |page=e.T167700A6369863 |doi=10.2305/IUCN.UK.2009-2.RLTS.T167700A6369863.en |access-date=11 November 2021}}</ref> | |||
| regnum = ]ia | |||
| taxon=Electrophorus electricus | |||
| phylum = ] | |||
| authority=(], 1766) | |||
| superclassis = ] | |||
| synonyms=''Gymnotus electricus'' | |||
| classis = ] | |||
| ordo = ] | |||
| familia = ] | |||
| genus = '''''Electrophorus''''' | |||
| genus_authority = ], 1864 | |||
| species = '''''E. electricus''''' | |||
| binomial = ''Electrophorus electricus'' | |||
| binomial_authority = (], 1766) | |||
}} | }} | ||
'''''Electrophorus electricus''''' is the best-known species of ]. It is a South American ]. Until the discovery of two additional species in 2019, the genus was classified as the ], with this species the only one in the genus.<ref name=Nature2019>{{cite journal |last1=de Santana |first1=C. David |last2=Crampton |first2=William G. R. |display-authors=etal |title=Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator |journal=Nature Communications |volume=10 |issue=1 |pages=4000 |date=September 2019 |pmid=31506444 |pmc=6736962 |doi=10.1038/s41467-019-11690-z |url=https://www.nature.com/articles/s41467-019-11690-z.pdf |access-date=2019-09-10 |archive-url=https://web.archive.org/web/20190910170231/https://www.nature.com/articles/s41467-019-11690-z.pdf |bibcode=2019NatCo..10.4000D |archive-date=2019-09-10 |doi-access=free }}</ref> Despite the name, it is not an ], but rather a ].<ref>{{Cite web |title=electric eel: Diet & Electric Shock |url=https://www.britannica.com/animal/Electrophorus-fish-genus |access-date=2022-01-20 |website=www.britannica.com}}</ref> It is considered as a freshwater ] which contains an electrogenic tissue that produces electric discharges.<ref name=":0">{{Cite journal |last1=Mermelstein |first1=Claudia Dos Santos |last2=Costa |first2=Manoel Luis |last3=Moura Neto |first3=Vivaldo |date=September 2000 |title=The cytoskeleton of the electric tissue of Electrophorus electricus, L. |journal=Anais da Academia Brasileira de Ciências | volume=72 | issue=3 | pages=341–351 | doi=10.1590/S0001-37652000000300008 |pmid=11028099 |issn=0001-3765 |doi-access=free}}</ref> | |||
The '''electric eel''' (''Electrophorus electricus'') is an ], and the ] in its genus. It is capable of generating powerful ] shocks of up to 650 volts, which it uses for hunting, self-defense and communicating with fellow eels. It is an ] in its ]n range. Despite its name, it is not an ], but rather a ]. | |||
==Taxonomic history== | |||
==Anatomy== | |||
The electric eel has an elongated, ] body, typically growing to about {{convert|2|m|abbr=on}} in length, and {{convert|20|kg|abbr=on}} in weight, making it the largest species of the ].<ref name="Albert, 2001">{{cite journal|last=Albert|first=J.S.|year= 2001|title=Species diversity and phylogenetic systematics of American knifefishes (Gymnotiformes, Teleostei)|journal=Misc. Publ.|publisher=Mus. Zool. University of Michigan|issue=190|pages=1–127|id={{hdl|2027.42/56433}}}}</ref> The coloration is dark gray-brown on the back and yellow or orange on the belly. Mature males have a darker color on the belly. They have no scales. The mouth is square, and positioned at the end of the snout. The anal fin extends the length of the body to the tip of the tail. As in other ostariophysan fishes, the swim bladder has two chambers. The anterior chamber is connected to the inner ear by a series of small bones derived from neck vertebrae called the ], which greatly enhances its hearing capability. The posterior chamber extends along the whole length of the body and maintains the fish's buoyancy. ''E electricus'' has a well-developed sense of hearing. This fish has a vascularized respiratory organ in its oral cavity<!-- (Albert, 2001)-->.{{Citation needed|date=November 2012}} As obligate air-breathers, electric eels must rise to the surface every 10 minutes or so to inhale before returning to the bottom. Nearly 80% of the oxygen used by the fish is retrieved in this way.<ref name="Johansen 1968">{{cite journal|last=Johansen|first=Kjell|year=1968|title=Gas Exchange and Control of Breathing in the Electric Eel, Electrophorus electricus|journal=Z. Vergl. Physiologie|publisher=Springer Berlin / Heidelberg|issue=Volume 61, Number 2 / June, 1968|pages=137–163|url=http://www.springerlink.com/content/v4gx677327634826/}}</ref> | |||
The species has been reclassified several times. When originally described by ] in 1766, he used the name ''Gymnotus electricus'', placing it in the same genus as '']'' (banded knifefish) which he had described several years earlier. It was only about a century later, in 1864, that the electric eel was moved to its own genus ''Electrophorus'' by ].<ref>{{cite book |last=Jordan |first=D. S. |year=1963 |title=The Genera of Fishes and a Classification of Fishes |url=https://archive.org/details/generaoffishesan0000jord |url-access=registration |page= |publisher=Stanford University Press |author-link1=David Starr Jordan }}</ref> | |||
In September 2019, David de Santana et al. suggested the division of the genus into three species based on DNA divergence, ecology and habitat, anatomy and physiology, and electrical ability: ''E. electricus'', '']'' sp. nov., and '']'' sp. nov. The study found ''E. electricus'' to be the ] to ''E. voltai'', with both species diverging during the ].<ref name=Nature2019/> | |||
==Anatomy== | |||
] | |||
''E. electricus'' has an elongated, ] body, typically growing to about {{convert|2|m|abbr=on}} in length, and {{convert |20 |kg |abbr=on}} in weight, making them the largest of the ].<!--NB This paper long precedes the recognition that Electrophorus is 3 species, so Albert may be referring to any of the 3, not necessarily E. electricus sensu stricto --><ref name="Albert, 2001">{{cite journal |last=Albert |first=J. S. |year=2001 |title=Species diversity and phylogenetic systematics of American knifefishes (Gymnotiformes, Teleostei) |journal=Miscellaneous Publications |issue=190 |pages=1–127 |hdl=2027.42/56433}}</ref> Their coloration is dark gray-brown on the back and yellow or orange on the belly. Mature females have a darker abdomen. They have no scales. The mouth is square and positioned at the end of the snout. The anal fin extends the length of the body to the tip of the tail. As in other ] fishes, the swim bladder has two chambers. The anterior chamber is connected to the inner ear by a series of small bones derived from neck vertebrae called the ], which greatly enhances its hearing capability. The posterior chamber extends along the whole length of the body and maintains the fish's buoyancy. | |||
''E. electricus'' has a vascularized respiratory system with gas exchange occurring through ] tissue in its ].<ref name="Boutilier, et. al. 1990">{{cite book |last=Boutilier |first=Robert |year=1990 |title=Vertebrate Gas Exchange: From Environment to Cell |series=Advances in Comparative & Environmental Physiology 6 |publisher=Springer-Verlag Berlin |page=285 |url=https://books.google.com/books?id=sfHxCAAAQBAJ&q=buccal%20cavity%20eel&pg=PA285 |isbn= 9783642753800}}</ref> As obligate air-breathers, ''E. electricus'' must rise to the surface every ten minutes or so to inhale before returning to the bottom. Nearly eighty percent of the ] used by the fish is obtained in this way.<ref name="Johansen 1968">{{cite journal |last=Johansen |first=Kjell |last2=Lenfant |first2=C. |last3=Schmidt-Nielsen |first3=Knut |author4-link=Knut Schmidt-Nielsen |last4=Petersen |first4=J. A. |title=Gas exchange and control of breathing in the electric eel, Electrophorus electricus. |journal=Zeitschrift für vergleichende Physiologie |date=June 1968 |volume=61 |issue=2 |pages=137–63 |doi=10.1007/BF00341112 |s2cid=22364103 }}</ref> | |||
Despite its name, the electric eel is not closely related to the true eels (Anguilliformes), but is a member of the neotropical knifefish order (Gymnotiformes), which is more closely related to the catfish. | |||
==Physiology== | ==Physiology== | ||
{{further |Electric eel#Electrophysiology}} | |||
].]] | |||
The electric eel has three abdominal pairs of organs that produce electricity: the main organ, the ], and the ]. These organs make up four-fifths of its body, and are what give the electric eel the ability to generate two types of ]s: low voltage and high voltage. These organs are made of ]s, lined up so a current of ions can flow through them and stacked so each one adds to a ] difference. When the eel locates its prey, the brain sends a signal through the nervous system to the electrocytes. This opens the ] channels, allowing ] to flow through, reversing the polarity momentarily. By causing a sudden difference in ], it generates an ] in a manner similar to a ], in which stacked plates each produce an electric potential difference. In the electric eel, some 5,000 to 6,000 stacked ] are capable of producing a shock at up to 600 ]s and 1 ] of current (600 ]s) for a duration of 2ms. It would be extremely unlikely for such a shock to be deadly for an adult human, due to the very short duration of the discharge. Still this level of current could in theory cause fatal ] in humans, depending on the path the current takes through the human body, and the duration of current flow.{{cn|date=September 2014}} ] (reversible via a heart defibrillator) can be triggered by an electric currents of 700 mA for more than 30 ms.{{cn|date=September 2014}} | |||
''E. electricus'' has three pairs of abdominal organs that produce electricity: the main organ, Hunter's organ, and Sachs' organ. These organs occupy a large part of its body, and give the electric eel the ability to generate two types of ]s: low voltage and high voltage. These organs are made of ]s, lined up so a current of ions can flow through them and stacked so each one adds to a potential difference.<ref name="PMC: PubMed Central">{{cite journal |last1=Xu |first1=Jian |last2=Lavan |first2=David A. |title=Designing artificial cells to harness the biological ion concentration gradient |journal=Nature Nanotechnology |volume=3 |issue=11 |pages=666–70 |date=November 2008 |pmid=18989332 |pmc=2767210 |doi=10.1038/nnano.2008.274 |bibcode=2008NatNa...3..666X }}</ref> The three electrical organs are developed from muscle and exhibit several biochemical properties and morphological features of the muscle sarcolemma; they are found symmetrically along both sides of the eel.<ref name=":0"/> | |||
When the eel finds its prey, the brain sends a signal through the ] to the electrocytes. This opens the ] channels, allowing ] to flow through, reversing the polarity momentarily. By causing a sudden difference in ], it generates an ] in a manner similar to a ], in which stacked plates each produce an electric potential difference.<ref name="PMC: PubMed Central"/> Electric eels are also capable of controlling their prey's nervous systems with their electrical abilities; by controlling their victim's nervous system and muscles via electrical pulses, they can keep prey from escaping or force it to move so they can locate its position.<ref>{{Cite news |url=https://www.bbc.com/news/science-environment-30335335 |title=Electric eels 'remotely control prey' |work=BBC News |date=2014-12-04 |last=Gill |first=Victoria }}</ref><ref>{{Cite web |url=https://www.sciencenews.org/article/electric-eels-remote-control-nervous-systems-prey |title=Electric eels remote-control nervous systems of prey |date=2015-02-17}}</ref> | |||
The Sach's organ is associated with ].<ref name=Fishbase/> Inside the organ are many muscle-like cells, called electrocytes. Each cell can only produce 0.15 V, though the organ can transmit a signal of nearly 10 V overall in amplitude at around 25 Hz in frequency. These signals are emitted by the main organ; the Hunter's organ can emit signals at rates of several hundred Hertz.<ref name=Fishbase/> | |||
] use electricity in multiple ways. Low voltages are used to sense the surrounding environment. High voltages are used to detect prey and, separately, stun them, at which point the electric eel applies a suction-feeding bite.<ref name=ShockAndAwe>{{cite journal |last=Catania |first=Kenneth C. |title=Shock & Awe |journal=Science American |date=April 2019 |volume=320 |issue=4 |pages=62–69}}</ref> | |||
The electric eel is unique among the Gymnotiformes in having large electric organs capable of producing potentially-lethal discharges that allow them to stun prey.<ref name=Nelson/> Larger voltages have been reported, but the typical output is sufficient to stun or deter virtually any animal. Juveniles produce smaller voltages (about 100 V). They are capable of varying the intensity of the electric discharge, using lower discharges for "hunting" and higher intensities for stunning prey, or defending themselves. When agitated, they are capable of producing these intermittent electric shocks over a period of at least an hour without signs of fatigue. | |||
]s]] | |||
The electric eel also possesses high-frequency-sensitive tuberous receptors, which are distributed in patches over its body. This feature is apparently useful for hunting other Gymnotiformes.<ref name=Fishbase/> | |||
Sachs' organ is associated with ]. Inside the organ are many muscle-like cells, called electrocytes. Each cell produces 0.15 V, the cells being stacked in series to enable the organ to generate nearly 10 V at around 25 Hz in frequency. These signals are emitted by the main organ; Hunter's organ can emit signals at rates of several hundred hertz.<ref name="Fishbase">{{FishBase |genus=Electrophorus |species=electricus |year=2005 |month=December}}</ref> | |||
Electric eels have been widely used as a model in the study of ].<ref name="Albert et al., 2008">{{cite journal|author=Albert, J.S., H. H. Zakon, P. K. Stoddard, G. A. Unguez, S. K.S. Holmberg, M. R. Sussman|year= 2008|title= The case for sequencing the genome of the electric eel, Electrophorus electricus|journal=J. Fish Biol.|volume=72|issue=2|pages=331–354|doi=10.1111/j.1095-8649.2007.01631.x}}</ref> The species is of some interest to researchers, who make use of its ] and ].<ref name=AChE>{{cite journal | last = Simon | first = Stéphanie | title = Cloning and Expression of Acetylcholinesterase from Electrophorus | journal = Journal of Biological Chemistry | volume = 272 | issue = 52 | pages = 33045–33055 | date = 1997-12-26 | url = http://www.jbc.org/cgi/content/full/272/52/33045 | accessdate = 2008-02-07 | doi = 10.1074/jbc.272.52.33045 | pmid = 9407087 | last2 = Massoulié | first2 = J}}</ref><ref name=ATP>{{cite journal |author=Zimmermann, H |author2=CR Denston |title=Adenosine triphosphate in cholinergic vesicles isolated from the electric organ of Electrophorus electricus |journal=Brain Res. |volume=111 |issue=2 |pages=365–76 |year=1976 |pmid=949609 |doi=10.1016/0006-8993(76)90780-0}}</ref> | |||
There are several physiological differences among the three electric organs, which allow them to have very different functions. The main electrical organ and the strong-voltage section of Hunter's organ are rich in ], a protein that is involved in high-voltage production.<ref>{{cite journal |last=Traeger |first=Lindsay L. |last2=Sabat |first2=Grzegorz |last3=Barrett-Wilt |first3=Gregory A. |last4=Wells |first4=Gregg B. |last5=Sussman |first5=Michael R. |display-authors=3 |title=A tail of two voltages: Proteomic comparison of the three electric organs of the electric eel |journal= ] |volume=3 |issue=7 |pages=e1700523 |date=July 2017 |pmid=28695212 |pmc=5498108 |doi=10.1126/sciadv.1700523 |bibcode=2017SciA....3E0523T }}</ref> Additionally, the three organs have varying amounts of ], which is a Na+/K+ ion pump that is crucial in the formation of voltage. The main and Hunter’s organs have a high expression of this protein, giving it a high sensitivity to changes in ion concentration, whereas Sachs' organ has a low expression of this protein.<ref>{{cite journal |last=Ching |first=Biyun |last2=Woo |first2=Jia M. |last3=Hiong |first3=Kum C. |last4=Boo |first4=Mel V. |last5=Choo |first5=Celine Y. L. |last6=Wong |first6=Wai P. |last7=Chew |first7=Shit F. |last8=Ip |first8=Yuen K. |display-authors=3 |title=Na+/K+-ATPase α-subunit (nkaα) isoforms and their mRNA expression levels, overall Nkaα protein abundance, and kinetic properties of Nka in the skeletal muscle and three electric organs of the electric eel, Electrophorus electricus |journal=PLOS ONE |volume=10 |issue=3 |pages=e0118352 |date=2015-03-20 |pmid=25793901 |pmc=4368207 |doi=10.1371/journal.pone.0118352 |bibcode=2015PLoSO..1018352C |doi-access=free }}</ref> | |||
=== Bionics === | |||
Researchers at ] and the ] argue artificial cells could be built that not only replicate the electrical behavior of electric eel cells, but also improve on them. Artificial versions of the eel's electricity-generating cells could be developed as a power source for medical implants and other microscopic devices.<ref>{{cite journal|author=Xu, Jian, David A. Lavan|title=Designing artificial cells to harness the biological ion concentration gradient|journal=Nature Nanotechnology |volume=3|pages=666–670|year=2008|doi=10.1038/nnano.2008.274|pmid=18989332|issue=11|pmc=2767210}}</ref> | |||
The typical output is sufficient to stun or deter virtually any animal. The eels can vary the intensity of the electric discharge, using lower discharges for hunting and higher intensities for stunning prey or defending themselves. They can also concentrate the discharge by curling up and making contact at two points along its body.<ref>{{cite journal |last=Catania |first=Kenneth C. |title=Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey |journal=Current Biology |volume=25 |issue=22 |pages=2889–98 |date=November 2015 |pmid=26521183 |doi=10.1016/j.cub.2015.09.036 |doi-access=free }}</ref> When agitated, they can produce these intermittent electric shocks over at least an hour without tiring.{{cn |date=June 2021}} | |||
''E. electricus'' also possesses high frequency–sensitive tuberous receptors, which are distributed in patches over its body. This feature is apparently useful for hunting other Gymnotiformes.<ref name=Fishbase/> ''E. electricus'' has been prominent in ].<ref name="Albert et al., 2008">{{cite journal |last1=Albert |first1=J. S. |last2=Zakon |first2=H. H. |last3=Stoddard |first3=P. K. |author4=G. A. Unguez |author5=S. K.S. Holmberg |author6=M. R. Sussman |display-authors=3 |year= 2008 |title= The case for sequencing the genome of the electric eel, Electrophorus electricus |journal=Journal of Fish Biology |volume=72 |issue=2 |pages=331–354 |doi=10.1111/j.1095-8649.2007.01631.x}}</ref> The species is of some interest to researchers, who make use of its ] and ].<ref name="AChE">{{cite journal |last1=Simon |first1=Stéphanie |last2=Massoulié |first2=J. |title=Cloning and expression of acetylcholinesterase from Electrophorus. Splicing pattern of the 3' exons in vivo and in transfected mammalian cells |journal=The Journal of Biological Chemistry |volume=272 |issue=52 |pages=33045–55 |date=December 1997 |pmid=9407087 |doi=10.1074/jbc.272.52.33045 |doi-access=free }}</ref><ref name="ATP">{{cite journal |last1=Zimmermann |first1=H. |last2=Denston |first2=C. R. |title=Adenosine triphosphate in cholinergic vesicles isolated from the electric organ of Electrophorus electricus |journal=Brain Research |volume=111 |issue=2 |pages=365–76 |date=July 1976 |pmid=949609 |doi=10.1016/0006-8993(76)90780-0 |s2cid=5619963 }}</ref> | |||
Despite being the first described species in the genus and thus the most famous example, ''E. electricus'' actually has the weakest maximum voltage of the three species in the genus, at only 480 volts (as opposed to 572 volts in ''E. varii'' and 860 volts in ''E. voltai'').<ref name="Nature2019" /> | |||
==Ecology and life history== | ==Ecology and life history== | ||
]]] | |||
===Habitat=== | ===Habitat=== | ||
Electric eels inhabit fresh waters of the ] and ] basins in South America, in floodplains, swamps, creeks, small rivers, and coastal plains. They often live on muddy bottoms in calm or stagnant waters.<ref name=Fishbase>{{FishBase species|genus=Electrophorus|species=electricus|year=2005|month=December}}</ref> | |||
''E. electricus'' is restricted to freshwater habitats in the ]. Populations in the ], ], and other parts of the Guiana Shield are now thought to belong to ''E. varii'' and ''E. voltai''.<ref>{{Cite web |title=Electrophorus electricus, Electric eel : fisheries, aquarium |url=https://www.fishbase.se/summary/4535 |access-date=2021-12-22 |website=www.fishbase.se}}</ref> | |||
===Feeding ecology=== | ===Feeding ecology=== | ||
''E. electricus'' feeds on ]s, although adult eels may also consume ] and small ]s, such as ]s. First-born hatchlings eat other eggs and embryos from later ]es.<ref name=Fishbase/> The juveniles eat invertebrates, such as ] and ]s.<!--plural because more than one species--> | |||
===Reproduction=== | ===Reproduction=== | ||
The electric eel is known for its unusual breeding behavior. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 3,000 young will hatch from the eggs in one nest. Male electric eels are much smaller than the females.<ref name="Piper">] (2007), ''Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals'', ].</ref><ref>{{cite journal|author=Assunção MIS|author2=Schwassmann HO|year=1995|title=Reproduction and larval development of ''Electrophorus electricus'' on Marajó Island (Pará, Brazil)|journal=Ichthyological Exploration of Freshwaters|volume=6|issue=2|pages=175–184|issn=0936-9902}}</ref> | |||
''E. electricus'' is known for its unusual breeding behavior. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 3,000 young hatch from the eggs in one nest. Males grow to be larger than females<ref>{{cite journal |last1=Assunção |first1=M. I. |last2=Schwassmann |first2=H. O. |year=1995 |title=Reproduction and larval development of ''Electrophorus electricus'' on Marajó Island (Pará, Brazil) |journal=Ichthyological Exploration of Freshwaters |volume=6 |issue=2 |pages=175–184 |issn=0936-9902}}</ref><ref name="Piper">] (2007), ''Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals'', ].</ref> by about {{convert |35 |cm |in |abbr=on}}.<ref>{{cite book |url=https://books.google.com/books?id=Gzc2DwAAQBAJ&pg=331 |title=Field guide to the fishes of the Amazon, Orinoco, and Guianas |publisher=Princeton University Press |year=2017 |isbn=9781400888801 |editor1-last=van der Sleen |editor1-first=P. |editor2-last=Albert |editor2-first=J. S. |pages=331 |oclc=1004848434 }}</ref> | |||
==In zoos and private collections== | |||
These fish have always been sought after by some animal collectors, but catching them is difficult, namely because the only reasonable option is to make the eels tired by continually discharging their electricity. The fish's electric organs will eventually become completely discharged, allowing the collector to wade into the water in comparative safety.<ref name="Piper" /> | |||
== References == | |||
Keeping electric eels in captivity is difficult and mostly limited to zoos and aquaria, although a few hobbyists have kept them as pets. <!-- An electric eel requires an aquarium of at least 750 l (200 gal). It generally must be kept in the tank by itself, although adult electric eels generally tolerate one another. Young eels will often fight if placed in the same aquarium. Electric eels cannot be kept with any other fish, as they will attack them.{{Citation needed|date=November 2009}} --> | |||
{{Reflist |30em}} | |||
== Further reading == | |||
==Taxonomic history== | |||
The species is so unusual that it has been reclassified several times. Originally, it was given its own family, Electrophoridae, and then was placed in a genus of ] alongside '']''.<ref name=Nelson>{{cite book | title = Fishes of the World | last = Nelson | first = Joseph, S. | publisher = John Wiley & Sons, Inc. | year = 2006 | isbn = 0-471-25031-7}}</ref> | |||
<!-- | |||
Uncited, not encyclopedic ==Popular culture== | |||
* Catania, Kenneth C., "The Shocking Predatory Strike of the Electric Eel", ''Science'', Vol.346, No.6214, (5 December 2014), pp. 1231–1234. | |||
Electric eels are common in ] television series, especially in comical situations in which the character is shocked by the eel. However, the eel depicted is usually a ] with electric shock abilities. | |||
* | |||
--> | |||
* {{cite journal |last1=Catania |first1=Kenneth C. |title=Power Transfer to a Human during an Electric Eel's Shocking Leap |journal=Current Biology |volume=27 |issue=18 |pages=2887–2891.e2 |doi=10.1016/j.cub.2017.08.034 |pmid=28918950 |year=2017 |doi-access=free |ref=none}} | |||
* Finger S., "Dr. Alexander Garden, a Linnaean in Colonial America, and the Saga of Five 'Electric Eels'", ''Perspectives in Biology and Medicine'', Vol.53, No.3, (Summer 2010), pp. 388–406. | |||
* Finger, S. & Piccolino, M., ''The Shocking History of Electric Fishes: From Ancient Epochs to the Birth of Modern Neurophysiology'', Oxford University Press, (New York), 2011. | |||
* {{cite journal |last1=Gervais |first1=R |year=2017 | title=Phenomenological Understanding and Electric Eels |url=http://www.ehu.eus/ojs/index.php/THEORIA/article/download/17294/15727 |journal=Theoria |volume=32 |issue=3 | pages=293–302 |doi=10.1387/theoria.17294 |doi-access=free |hdl=10067/1486000151162165141 |hdl-access=free |ref=none}} | |||
* Plumb, G., "The 'Electric Stroke' and the 'Electric Spark': Anatomists and Eroticism at George Baker's Electric Eel Exhibition in 1776 and 1777", ''Endeavour'', Vol.34, No.3, (September 2010), pp. 87–94. | |||
* {{cite journal |last1=Traeger |first1=L.L. |last2=Sabat |first2=G. |last3=Barrett-Wilt |first3=G.A. |last4=Wells |first4=G.B. |last5=Sussman |first5=M.R. |title=A Tail of Two Voltages: Proteomic Comparison of the Three Electric Organs of the Electric Eel |journal=Science Advances |volume=3 |issue=7 | page=e1700523 |doi=10.1126/sciadv.1700523 | pmid=28695212 |pmc=5498108 |bibcode=2017SciA....3E0523T |date=July 2017 |ref=none}} | |||
* Turkel, W.J., ''Spark from the Deep: How Shocking Experiments with Strongly Electric Fish Powered Scientific Discovery'', Johns Hopkins University Press, (Baltimore), 2013. | |||
== |
== External links == | ||
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Latest revision as of 21:57, 15 April 2024
South American electric fish
Electrophorus electricus | |
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Electric eel at the New England Aquarium, United States | |
Conservation status | |
Least Concern (IUCN 3.1) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Gymnotiformes |
Family: | Gymnotidae |
Genus: | Electrophorus |
Species: | E. electricus |
Binomial name | |
Electrophorus electricus (Linnaeus, 1766) | |
Synonyms | |
Gymnotus electricus |
Electrophorus electricus is the best-known species of electric eel. It is a South American electric fish. Until the discovery of two additional species in 2019, the genus was classified as the monotypic, with this species the only one in the genus. Despite the name, it is not an eel, but rather a knifefish. It is considered as a freshwater teleost which contains an electrogenic tissue that produces electric discharges.
Taxonomic history
The species has been reclassified several times. When originally described by Carl Linnaeus in 1766, he used the name Gymnotus electricus, placing it in the same genus as Gymnotus carapo (banded knifefish) which he had described several years earlier. It was only about a century later, in 1864, that the electric eel was moved to its own genus Electrophorus by Theodore Gill.
In September 2019, David de Santana et al. suggested the division of the genus into three species based on DNA divergence, ecology and habitat, anatomy and physiology, and electrical ability: E. electricus, E. voltai sp. nov., and E. varii sp. nov. The study found E. electricus to be the sister species to E. voltai, with both species diverging during the Pliocene.
Anatomy
E. electricus has an elongated, cylindrical body, typically growing to about 2 m (6 ft 7 in) in length, and 20 kg (44 lb) in weight, making them the largest of the Gymnotiformes. Their coloration is dark gray-brown on the back and yellow or orange on the belly. Mature females have a darker abdomen. They have no scales. The mouth is square and positioned at the end of the snout. The anal fin extends the length of the body to the tip of the tail. As in other ostariophysan fishes, the swim bladder has two chambers. The anterior chamber is connected to the inner ear by a series of small bones derived from neck vertebrae called the Weberian apparatus, which greatly enhances its hearing capability. The posterior chamber extends along the whole length of the body and maintains the fish's buoyancy.
E. electricus has a vascularized respiratory system with gas exchange occurring through epithelial tissue in its buccal cavity. As obligate air-breathers, E. electricus must rise to the surface every ten minutes or so to inhale before returning to the bottom. Nearly eighty percent of the oxygen used by the fish is obtained in this way.
Physiology
Further information: Electric eel § ElectrophysiologyE. electricus has three pairs of abdominal organs that produce electricity: the main organ, Hunter's organ, and Sachs' organ. These organs occupy a large part of its body, and give the electric eel the ability to generate two types of electric organ discharges: low voltage and high voltage. These organs are made of electrocytes, lined up so a current of ions can flow through them and stacked so each one adds to a potential difference. The three electrical organs are developed from muscle and exhibit several biochemical properties and morphological features of the muscle sarcolemma; they are found symmetrically along both sides of the eel.
When the eel finds its prey, the brain sends a signal through the nervous system to the electrocytes. This opens the ion channels, allowing sodium to flow through, reversing the polarity momentarily. By causing a sudden difference in electric potential, it generates an electric current in a manner similar to a battery, in which stacked plates each produce an electric potential difference. Electric eels are also capable of controlling their prey's nervous systems with their electrical abilities; by controlling their victim's nervous system and muscles via electrical pulses, they can keep prey from escaping or force it to move so they can locate its position.
Electric eels use electricity in multiple ways. Low voltages are used to sense the surrounding environment. High voltages are used to detect prey and, separately, stun them, at which point the electric eel applies a suction-feeding bite.
Sachs' organ is associated with electrolocation. Inside the organ are many muscle-like cells, called electrocytes. Each cell produces 0.15 V, the cells being stacked in series to enable the organ to generate nearly 10 V at around 25 Hz in frequency. These signals are emitted by the main organ; Hunter's organ can emit signals at rates of several hundred hertz.
There are several physiological differences among the three electric organs, which allow them to have very different functions. The main electrical organ and the strong-voltage section of Hunter's organ are rich in calmodulin, a protein that is involved in high-voltage production. Additionally, the three organs have varying amounts of Na+/K+-ATPase, which is a Na+/K+ ion pump that is crucial in the formation of voltage. The main and Hunter’s organs have a high expression of this protein, giving it a high sensitivity to changes in ion concentration, whereas Sachs' organ has a low expression of this protein.
The typical output is sufficient to stun or deter virtually any animal. The eels can vary the intensity of the electric discharge, using lower discharges for hunting and higher intensities for stunning prey or defending themselves. They can also concentrate the discharge by curling up and making contact at two points along its body. When agitated, they can produce these intermittent electric shocks over at least an hour without tiring.
E. electricus also possesses high frequency–sensitive tuberous receptors, which are distributed in patches over its body. This feature is apparently useful for hunting other Gymnotiformes. E. electricus has been prominent in the study of bioelectricity since the 18th century. The species is of some interest to researchers, who make use of its acetylcholinesterase and adenosine triphosphate.
Despite being the first described species in the genus and thus the most famous example, E. electricus actually has the weakest maximum voltage of the three species in the genus, at only 480 volts (as opposed to 572 volts in E. varii and 860 volts in E. voltai).
Ecology and life history
Habitat
E. electricus is restricted to freshwater habitats in the Guiana Shield. Populations in the Amazon basin, Brazilian Shield, and other parts of the Guiana Shield are now thought to belong to E. varii and E. voltai.
Feeding ecology
E. electricus feeds on invertebrates, although adult eels may also consume fish and small mammals, such as rats. First-born hatchlings eat other eggs and embryos from later clutches. The juveniles eat invertebrates, such as shrimp and crabs.
Reproduction
E. electricus is known for its unusual breeding behavior. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 3,000 young hatch from the eggs in one nest. Males grow to be larger than females by about 35 cm (14 in).
References
- Reis, R.; Lima, F. (2009). "Electrophorus electricus". IUCN Red List of Threatened Species. 2009: e.T167700A6369863. doi:10.2305/IUCN.UK.2009-2.RLTS.T167700A6369863.en. Retrieved 11 November 2021.
- ^ de Santana, C. David; Crampton, William G. R.; et al. (September 2019). "Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator" (PDF). Nature Communications. 10 (1): 4000. Bibcode:2019NatCo..10.4000D. doi:10.1038/s41467-019-11690-z. PMC 6736962. PMID 31506444. Archived from the original (PDF) on 2019-09-10. Retrieved 2019-09-10.
- "electric eel: Diet & Electric Shock". www.britannica.com. Retrieved 2022-01-20.
- ^ Mermelstein, Claudia Dos Santos; Costa, Manoel Luis; Moura Neto, Vivaldo (September 2000). "The cytoskeleton of the electric tissue of Electrophorus electricus, L." Anais da Academia Brasileira de Ciências. 72 (3): 341–351. doi:10.1590/S0001-37652000000300008. ISSN 0001-3765. PMID 11028099.
- Jordan, D. S. (1963). The Genera of Fishes and a Classification of Fishes. Stanford University Press. p. 330.
- Albert, J. S. (2001). "Species diversity and phylogenetic systematics of American knifefishes (Gymnotiformes, Teleostei)". Miscellaneous Publications (190): 1–127. hdl:2027.42/56433.
- Boutilier, Robert (1990). Vertebrate Gas Exchange: From Environment to Cell. Advances in Comparative & Environmental Physiology 6. Springer-Verlag Berlin. p. 285. ISBN 9783642753800.
- Johansen, Kjell; Lenfant, C.; Schmidt-Nielsen, Knut; Petersen, J. A. (June 1968). "Gas exchange and control of breathing in the electric eel, Electrophorus electricus". Zeitschrift für vergleichende Physiologie. 61 (2): 137–63. doi:10.1007/BF00341112. S2CID 22364103.
- ^ Xu, Jian; Lavan, David A. (November 2008). "Designing artificial cells to harness the biological ion concentration gradient". Nature Nanotechnology. 3 (11): 666–70. Bibcode:2008NatNa...3..666X. doi:10.1038/nnano.2008.274. PMC 2767210. PMID 18989332.
- Gill, Victoria (2014-12-04). "Electric eels 'remotely control prey'". BBC News.
- "Electric eels remote-control nervous systems of prey". 2015-02-17.
- Catania, Kenneth C. (April 2019). "Shock & Awe". Science American. 320 (4): 62–69.
- ^ Froese, Rainer; Pauly, Daniel (eds.). "Electrophorus electricus". FishBase. December 2005 version.
- Traeger, Lindsay L.; Sabat, Grzegorz; Barrett-Wilt, Gregory A.; et al. (July 2017). "A tail of two voltages: Proteomic comparison of the three electric organs of the electric eel". Science Advances. 3 (7): e1700523. Bibcode:2017SciA....3E0523T. doi:10.1126/sciadv.1700523. PMC 5498108. PMID 28695212.
- Ching, Biyun; Woo, Jia M.; Hiong, Kum C.; et al. (2015-03-20). "Na+/K+-ATPase α-subunit (nkaα) isoforms and their mRNA expression levels, overall Nkaα protein abundance, and kinetic properties of Nka in the skeletal muscle and three electric organs of the electric eel, Electrophorus electricus". PLOS ONE. 10 (3): e0118352. Bibcode:2015PLoSO..1018352C. doi:10.1371/journal.pone.0118352. PMC 4368207. PMID 25793901.
- Catania, Kenneth C. (November 2015). "Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey". Current Biology. 25 (22): 2889–98. doi:10.1016/j.cub.2015.09.036. PMID 26521183.
- Albert, J. S.; Zakon, H. H.; Stoddard, P. K.; et al. (2008). "The case for sequencing the genome of the electric eel, Electrophorus electricus". Journal of Fish Biology. 72 (2): 331–354. doi:10.1111/j.1095-8649.2007.01631.x.
- Simon, Stéphanie; Massoulié, J. (December 1997). "Cloning and expression of acetylcholinesterase from Electrophorus. Splicing pattern of the 3' exons in vivo and in transfected mammalian cells". The Journal of Biological Chemistry. 272 (52): 33045–55. doi:10.1074/jbc.272.52.33045. PMID 9407087.
- Zimmermann, H.; Denston, C. R. (July 1976). "Adenosine triphosphate in cholinergic vesicles isolated from the electric organ of Electrophorus electricus". Brain Research. 111 (2): 365–76. doi:10.1016/0006-8993(76)90780-0. PMID 949609. S2CID 5619963.
- "Electrophorus electricus, Electric eel : fisheries, aquarium". www.fishbase.se. Retrieved 2021-12-22.
- Assunção, M. I.; Schwassmann, H. O. (1995). "Reproduction and larval development of Electrophorus electricus on Marajó Island (Pará, Brazil)". Ichthyological Exploration of Freshwaters. 6 (2): 175–184. ISSN 0936-9902.
- Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
- van der Sleen, P.; Albert, J. S., eds. (2017). Field guide to the fishes of the Amazon, Orinoco, and Guianas. Princeton University Press. p. 331. ISBN 9781400888801. OCLC 1004848434.
Further reading
- Catania, Kenneth C., "The Shocking Predatory Strike of the Electric Eel", Science, Vol.346, No.6214, (5 December 2014), pp. 1231–1234.
- Catania, K.C., "Leaping Eels Electrify Threats, Supporting Humboldt’s Account of a Battle with Horses", Proceedings of the National Academy of Sciences, Vol.113, No.13 (21 June 2016), pp.6979-6984.
- Catania, Kenneth C. (2017). "Power Transfer to a Human during an Electric Eel's Shocking Leap". Current Biology. 27 (18): 2887–2891.e2. doi:10.1016/j.cub.2017.08.034. PMID 28918950.
- Finger S., "Dr. Alexander Garden, a Linnaean in Colonial America, and the Saga of Five 'Electric Eels'", Perspectives in Biology and Medicine, Vol.53, No.3, (Summer 2010), pp. 388–406.
- Finger, S. & Piccolino, M., The Shocking History of Electric Fishes: From Ancient Epochs to the Birth of Modern Neurophysiology, Oxford University Press, (New York), 2011.
- Gervais, R (2017). "Phenomenological Understanding and Electric Eels". Theoria. 32 (3): 293–302. doi:10.1387/theoria.17294. hdl:10067/1486000151162165141.
- Plumb, G., "The 'Electric Stroke' and the 'Electric Spark': Anatomists and Eroticism at George Baker's Electric Eel Exhibition in 1776 and 1777", Endeavour, Vol.34, No.3, (September 2010), pp. 87–94.
- Traeger, L.L.; Sabat, G.; Barrett-Wilt, G.A.; Wells, G.B.; Sussman, M.R. (July 2017). "A Tail of Two Voltages: Proteomic Comparison of the Three Electric Organs of the Electric Eel". Science Advances. 3 (7): e1700523. Bibcode:2017SciA....3E0523T. doi:10.1126/sciadv.1700523. PMC 5498108. PMID 28695212.
- Turkel, W.J., Spark from the Deep: How Shocking Experiments with Strongly Electric Fish Powered Scientific Discovery, Johns Hopkins University Press, (Baltimore), 2013.
External links
- [REDACTED] Data related to Electrophorus electricus at Wikispecies
- [REDACTED] Media related to Electrophorus electricus at Wikimedia Commons
- 1954 educational film about the electric eel from the Moody Institute of Science
Taxon identifiers | |
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Electrophorus electricus |