Editing Electroreception and electrogenesis

{{good article}}
{{Short description|Biological electricity-related abilities}}
[[File:Electroreception system in Elephantfish.svg|thumb|upright=1.75|The [[elephantnose fish]] is a weakly electric [[Mormyridae|mormyrid]] fish which generates an [[electric field]] with its [[Electric organ (biology)|electric organ]] and then uses its electroreceptive [[knollenorgan]]s and mormyromasts to locate nearby objects by the distortions they cause in the electric field.<ref name="von der Emde 1999">{{cite journal |last=von der Emde |first=G. |title=Active electrolocation of objects in weakly electric fish |journal=[[Journal of Experimental Biology]] |volume=202 |issue=10 |date=15 May 1999 |doi=10.1242/jeb.202.10.1205 |pages=1205–1215|pmid=10210662 }}</ref>]]

'''Electroreception''' and '''electrogenesis''' are the closely related biological abilities to perceive [[electrical]] stimuli and to generate [[electric field]]s. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes, such as the [[electric eel]], to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better [[Conductor (material)|conductor]] of electricity than air. In passive electrolocation, objects such as prey are detected by sensing the electric fields they create. In active electrolocation, fish generate a weak electric field and sense the different distortions of that field created by objects that conduct or resist electricity. Active electrolocation is practised by two groups of weakly [[electric fish]], the order [[Gymnotiformes]] (knifefishes) and family [[Mormyridae]] (elephantfishes), and by the monotypic genus ''[[Gymnarchus]]'' (African knifefish). An electric fish generates an electric field using an [[Electric organ (biology)|electric organ]], [[Evolution|modified]] from muscles in its tail. The field is called weak if it is only enough to detect prey, and strong if it is powerful enough to stun or kill. The field may be in brief pulses, as in the elephantfishes, or a continuous wave, as in the knifefishes. Some strongly electric fish, such as the electric eel, locate prey by generating a weak electric field, and then discharge their electric organs strongly to stun the prey; other strongly electric fish, such as the [[electric ray]], electrolocate passively. The [[Stargazer (fish)|stargazers]] are unique in being strongly electric but not using electrolocation.

The electroreceptive [[ampullae of Lorenzini]] evolved early in the history of the vertebrates; they are found in both [[Chondrichthyes|cartilaginous fishes]] such as [[shark]]s, and in [[Osteichthyes|bony fishes]] such as [[coelacanth]]s and [[sturgeon]]s, and must therefore be ancient. Most bony fishes have secondarily lost their ampullae of Lorenzini, but other non-[[Homology (biology)|homologous]] electroreceptors have repeatedly evolved, including in two groups of [[mammal]]s, the [[monotreme]]s ([[platypus]] and [[echidna]]s) and the [[cetacea]]ns ([[Guiana dolphin]]).

== History == 

{{main|History of bioelectricity}}

[[File:Gymnarchus niloticus005 (cropped).JPG|thumb|upright=1.3|[[Hans Lissmann (zoologist)|Hans Lissmann]] discovered electroreception in 1950 through his observations of ''[[Gymnarchus niloticus]]''.<ref name="Alexander 2006"/>]]

In 1678, while doing dissections of sharks, the Italian physician [[Stefano Lorenzini]] discovered organs on their heads now called ampullae of Lorenzini. He published his findings in ''Osservazioni intorno alle torpedini''.<ref>{{cite book |last=Lorenzini |first=Stefano |author-link=Stefano Lorenzini |title=Osservazioni intorno alle torpedini |date=1678 |publisher=Per l'Onofri |location=Florence, Italy |doi=10.5962/bhl.title.6883 |oclc=2900213 }}</ref> The electroreceptive function of these organs was established by R. W. Murray in 1960.<ref name="Murray_1960">{{cite journal |last=Murray |first=R. W. |title=Electrical sensitivity of the ampullae of Lorenzini |journal=[[Nature (journal)|Nature]] |volume=187 |issue=4741 |pages=957 |date=September 1960 |pmid=13727039 |doi=10.1038/187957a0 |bibcode=1960Natur.187..957M |doi-access=free }}</ref><ref name="Murray_1962">{{cite journal|last=Murray |first=R. W. |title=The response of the ampullae of Lorenzini of elasmobranchs to electrical stimulation |journal=[[Journal of Experimental Biology]] |volume=39 |issue=|pages=119–28 |date=March 1962 |pmid=14477490 |doi=10.1242/jeb.39.1.119 }}</ref>

In 1921, the German anatomist Viktor Franz<!-- 1883–1950, see https://www.conchology.be/?t=9001&id=18664 for bio--> described the [[knollenorgan]]s (tuberous organs) in the skin of the [[Mormyridae|elephantfishes]], again without knowledge of their function as electroreceptors.<ref name="Franz 1921">{{cite journal |last=Franz |first=Viktor <!--J.--> |year=1921 |title=Zur mikroscopischen Anatomie der Mormyriden |journal=Zoologisch Jahrbuch Abteilung für Anatomie und Ontogonie |volume=42 |pages=91–148}}</ref>

In 1949, the Ukrainian-British zoologist [[Hans Lissmann (zoologist)|Hans Lissmann]] noticed that the [[Gymnarchus|African knife fish (''Gymnarchus niloticus'')]] was able to swim backwards at the same speed and with the same dexterity around obstacles as when it swam forwards, avoiding collisions. He demonstrated in 1950 that the fish was producing a variable electric field, and that the fish reacted to any change in the electric field around it.<ref name="Alexander 2006">{{cite journal |last=Alexander |first=R. McNeill |authorlink=R. McNeill Alexander |title=A new sense for muddy water |journal=[[Journal of Experimental Biology]] |volume=2006 209: 200-201; doi: 10.1242/jeb.10.1242/jeb.02012 |issue=2 |pages=200–201  |doi=10.1242/jeb.10.1242/jeb.02012 |year=2006 |pmid=16391343 |doi-access= }}</ref><ref name="Lissmann">[[Hans Lissmann (zoologist)|Lissmann, Hans]]. "[https://www.nature.com/articles/167201a0 Continuous Electrical Signals from the Tail of a Fish, ''Gymnarchus Niloticus'' Cuv]", in: ''[[Nature (journal)|Nature]]'', 167, 4240 (1951), pp. 201–202.
* "[https://jeb.biologists.org/content/35/2/451 The Mechanism of Object Location in ''Gymnarchus Niloticus'' and Similar Fish]", in: ''[[Journal of Experimental Biology]]'', 35 (1958), pp. 451–486. (with Ken E. Machin)
* "[https://jeb.biologists.org/content/37/4/801 The Mode of Operation of the Electric Receptors in ''Gymnarchus Niloticus'']", in: ''[[Journal of Experimental Biology]]'' 37:4 (1960), pp. 801–811. (with Ken E. Machin)
* "[https://www.jstor.org/stable/24936498?seq=1#page_scan_tab_contents Electric Location by Fishes]", in: ''[[Scientific American]]'', 208, pp 50–59, March 1963.</ref>{{-}}

== Electrolocation ==

{{multiple image
|image1=Electroreceptors in a sharks head.svg
|caption1=The electroreceptive [[ampullae of Lorenzini]] (red dots) evolved from the mechanosensory [[lateral line]] organs (gray lines) of early vertebrates.<ref name="King Hu Long"/> They are seen here in the head of a [[shark]].
|image2=Ampullae of Lorenzini.svg
|caption2=Ampullae of Lorenzini, found in several basal groups of fishes, are jelly-filled canals connecting pores in the skin to sensory bulbs. They detect small differences in [[Electric potential|electrical potential]] between their two ends.
|width1=250
|width2=205
}}

Electroreceptive animals use the sense to locate objects around them. This is important in [[ecological niche]]s where the animal cannot depend on vision: for example in caves, in murky water, and at night. Electrolocation can be passive, sensing electric fields such as those generated by the muscle movements of buried prey, or active, the electrogenic predator generating a weak electric field to allow it to distinguish between conducting and non-conducting objects in its vicinity.<ref name="Crampton 2019">{{Cite journal |last=Crampton |first=William G. R. |date=5 February 2019 |title=Electroreception, electrogenesis and electric signal evolution |journal=[[Journal of Fish Biology]] |volume=95 |issue=1 |pages=92–134 |doi=10.1111/jfb.13922 |pmid=30729523 |s2cid=73442571 |doi-access=free |bibcode=2019JFBio..95...92C }}</ref>

=== Passive electrolocation ===

In passive electrolocation, the animal senses the weak [[Bioelectromagnetism|bioelectric fields]] generated by other animals and uses it to locate them. These electric fields are generated by all animals due to the activity of their nerves and muscles. A second source of electric fields in fish is the [[Ion pump (biology)|ion pump]] associated with [[osmoregulation]] at the [[gill]] membrane. This field is modulated by the opening and closing of the mouth and gill slits.<ref name="Coplin2004"/><ref>{{cite journal |last1=Bodznick |first1=D. |last2=Montgomery |first2=J. C. |last3=Bradley |first3=D. J. |title=Suppression of Common Mode Signals Within the Electrosensory System of the Little Skate ''Raja erinacea'' |journal=[[Journal of Experimental Biology]] |year=1992 |volume=171 |issue=Pt 1 |pages=107–125 |doi=10.1242/jeb.171.1.107 |url=http://jeb.biologists.org/content/171/1/107.full.pdf |doi-access=free }}</ref>
Passive electroreception usually relies upon ampullary receptors such as ampullae of Lorenzini which are sensitive to low frequency stimuli, below 50&nbsp;Hz. These receptors have a jelly-filled canal leading from the sensory receptors to the skin surface.<ref name="King Hu Long"/><ref name="Crampton 2019"/>

=== Active electrolocation ===

{{further|Electric fish|Electric organ (biology)}}

{{multiple image
|image1=Knollenorgan by Viktor Franz 1921.gif
|caption1=A [[knollenorgan]], a tuberous electroreceptor of weakly electric fish. RC=receptor cell; b.m.=basal membrane; n=nerve.
|image2=Mormyromast diagram.svg
|caption2=A Mormyromast, a type of electroreceptor found only in [[Mormyroidea|Mormyrid]] fishes
|width1=278
|width2=145
}}

In active electrolocation,<ref name="Albert Crampton 2006">{{ cite book |last1=Albert |first1=J. S. |last2=Crampton |first2=W. G. |year=2006 |chapter=Electroreception and Electrogenesis |pages=429–470 |editor=Lutz, P. L. |title=The Physiology of Fishes |publisher=CRC Press |location=Boca Raton, Florida |isbn=978-0-8493-2022-4 }}</ref> the animal senses its surrounding environment by generating weak [[electric field]]s (electrogenesis) and detecting distortions in these fields using electroreceptor organs. This electric field is generated by means of a specialised [[Electric organ (biology)|electric organ]] consisting of modified muscle or nerves.<ref name="Bullock Hanstra Scheich 1972">{{cite journal |last1=Bullock |first1=Theodore H. |author1-link=Theodore Holmes Bullock |last2=Hamstra | first2=R. Jr. |last3=Scheich |first3=H. |year=1972 |title=The jamming avoidance response of high frequency electric fish |journal=[[Journal of Comparative Physiology]] |issue=77 |pages=1–22}}</ref> Animals that use active electroreception include the [[weakly electric fish]], which either generate small electrical pulses (termed "pulse-type"), as in the Mormyridae, or produce a quasi-[[Sine wave|sinusoidal]] discharge from the electric organ (termed "wave-type"), as in the Gymnotidae.<ref name="Babineau 2006">{{Cite journal |last1=Babineau |first1=D. |last2=Longtin |first2=A. |last3=Lewis |first3=J. E. |title=Modeling the Electric Field of Weakly Electric Fish |journal=[[Journal of Experimental Biology]] |year=2006 |volume=209 |issue=Pt 18 |pages=3636–3651 |doi=10.1242/jeb.02403 |pmid=16943504 |doi-access= }}</ref>

Many of these fish, such as ''[[Gymnarchus]]'' and ''[[Apteronotus]]'', keep their body rather rigid, swimming forwards or backwards with equal facility by undulating [[fin]]s that extend most of the length of their bodies. Swimming backwards may help them to search for and assess prey using electrosensory cues. Experiments by Lannoo and Lannoo in 1993 support Lissmann's proposal that this style of swimming with a straight back works effectively given the constraints of active electrolocation. ''Apteronotus'' can select and catch larger ''[[Daphnia]]'' water fleas among smaller ones, and they do not discriminate against artificially-darkened water fleas, in both cases with or without light.<ref name="Lissmann"/><ref name="Lannoo Lannoo 1993">{{cite journal |last1=Lannoo |first1=Michael J. |last2=Lannoo |first2=Susan Johnson |title=Why do electric fishes swim backwards? An hypothesis based on gymnotiform foraging behavior interpreted through sensory constraints |journal=[[Environmental Biology of Fishes]] |volume=36 |issue=2 |year=1993 |doi=10.1007/bf00002795 |pages=157–165|bibcode=1993EnvBF..36..157L |s2cid=109426 }}</ref>

These fish create a potential usually smaller than one [[volt]] (1 V). Weakly electric fish can discriminate between objects with different [[resistance (physics)|resistance]] and [[capacitance]] values, which may help in identifying objects. Active electroreception typically has a range of about one body length, though objects with an [[electrical impedance]] similar to that of the surrounding water are nearly undetectable.<ref name="Albert Crampton 2006"/><ref name="Bullock Hanstra Scheich 1972"/><ref name="Babineau 2006"/>

Active electrolocation relies upon tuberous electroreceptors which are sensitive to high frequency (20-20,000&nbsp;[[Hertz|Hz]]) stimuli. These receptors have a loose plug of [[epithelial]] cells which [[Capacitance|capacitively]] couples the sensory receptor cells to the external environment. [[Mormyridae|Elephantfish]] (Mormyridae) from Africa have tuberous electroreceptors known as [[Knollenorgans]] and Mormyromasts in their skin.<ref name="Bennett 1965">{{cite journal |last=Bennett |first=M. V. L. |year=1965 |title=Electroreceptors in Mormyrids |journal=[[Cold Spring Harbor Symposia on Quantitative Biology]] |volume=30 |issue=30 |pages=245–262|doi=10.1101/SQB.1965.030.01.027 |pmid=5219479 }}</ref><ref name="Engelmann Nöbel Röver van der Emde 2009">{{Cite journal |last1=Engelmann |first1=Jacob |last2=Nöbel |first2=Sabine |last3=Röver |first3=Timo |last4=von der Emde |first4=Gerhard |year=2009 |title=The Schnauzenorgan-response of Gnathonemus petersii |url=http://www.frontiersinzoology.com/content/pdf/1742-9994-6-21.pdf |journal=[[Frontiers in Zoology]] |volume=6 |issue=21 |pages=1–15 |doi=10.1186/1742-9994-6-21 |pmid=19772622 |pmc=2760544 |doi-access=free }}</ref><ref name="Engelmann Bacelo Metzen Pusch 2008">{{cite journal |last1=Engelmann |first1=Jacob |last2=Bacelo |first2=João |last3=Metzen |first3=Michael |last4=Pusch |first4=Roland |last5=Bouton |first5=Beatrice |last6=Migliaro |first6=Adriana |last7=Caputi |first7=Angel |last8=Budelli |first8=Ruben |last9=Grant |first9=Kirsty |last10=von der Emde |first10=Gerhard |title=Electric imaging through active electrolocation: implication for the analysis of complex scenes |journal=Biological Cybernetics |volume=98 |issue=6 |date=20 May 2008 |doi=10.1007/s00422-008-0213-5 |pages=519–539 |pmid=18491164 |s2cid=2975352 |url=https://www.researchgate.net/publication/5359612_Electric_imaging_through_active_electrolocation_Implication_for_the_analysis_of_complex_scenes<!--not redundant to DOI-->}}</ref>

Elephantfish emit short pulses to locate their prey. [[Capacitance|Capacitative]] and [[resistive]] objects affect the electric field differently, enabling the fish to locate objects of different types within a distance of about a body length. Resistive objects increase the amplitude of the pulse; capacitative objects introduce distortions.<ref name="von der Emde 1999"/>

<gallery mode="packed" heights="200px">
File:Electroreception of Capacitative and Resistive Objects in Elephantfish.svg|Electrolocation of capacitative and resistive objects in elephantfish. The fish emits brief pulses from its electric organ; its electroreceptors detect signals modified by the electrical properties of the objects around it.<ref name="von der Emde 1999"/>
File:Scene analysis in electroreception coloured.jpg|For the [[Mormyridae|elephantfish]], the electric organ in the tail (blue) generates an [[electric field]] (cyan). This is sensed by electroreceptors in the skin, including two electric pits (foveas) to actively search and inspect objects. Shown are the field distortions created by two different types of objects: a plant that conducts better than water (green) and a non-conducting stone (brown).<ref name="Lewicki Olshausen Surlykke 2014">{{cite journal |last1=Lewicki |first1=M. S. |last2=Olshausen |first2=B. A. |last3=Surlykke |first3=A. |last4=Moss |first4=C. F. |year=2014 |title=Scene analysis in the natural environment |journal=[[Frontiers in Psychology]] |volume=5 |page=199 |doi=10.3389/fpsyg.2014.00199 |pmid=24744740 |pmc=3978336 |doi-access=free }}</ref>
</gallery>

The [[Gymnotiformes]], including the [[glass knifefish]] (Sternopygidae) and the [[electric eel]] (Gymnotidae), differ from the Mormyridae in emitting a continuous wave, approximating a sine wave, from their electric organ. As in the Mormyridae, the generated electric field enables them to discriminate accurately between capacitative and resistive objects.<ref name="von der Emde 1999"/>

{|style=text-align:center; style="margin:1em auto;"
|[[File:Electroreception of Capacitative and Resistive Objects in Glass Knifefish.svg|400px]]
Electrolocation of capacitative and resistive objects in glass knifefish.<br/>Many [[Naked-back knifefish|gymnotid]] fish generate a continuous electrical wave, which is<br/>distorted differently by objects according to their conductivity.
|[[File:Electric eel's electric organs.svg|400px]]
The [[electric eel]]'s [[Electric organ (biology)|electric organs]] occupy much of its body.<br/>They can discharge both weakly for electrolocation<br/>and strongly to stun prey.
|}

== Electrocommunication ==

[[File:Sidderaal (4039238527).jpg|thumb|upright=1.2|[[Electric eel]]s<!--3 species--> create [[electric field]]s powerful enough to stun prey using modified [[muscle]]s. Some weakly electric knifefishes appear to mimic the electric eel's discharge patterns; this may be [[Batesian mimicry]], to deceive predators that they are too dangerous to attack.<ref name="Stoddard 1999"/>]]

Weakly electric fish can communicate by modulating the electrical [[waveform]] they generate. They may use this to attract mates and in territorial displays.<ref>{{cite journal |last=Hopkins |first=C. D. |title=Design features for electric communication |journal=[[Journal of Experimental Biology]] |year=1999 |volume=202 |issue=Pt 10 |pages=1217–1228 |doi=10.1242/jeb.202.10.1217 |pmid=10210663 }}</ref> Electric catfish frequently use their electric discharges to ward off other species from their shelter sites, whereas with their own species they have ritualized fights with open-mouth displays and sometimes bites, but rarely use electric organ discharges.<ref name="Rankin Moller 2010">{{cite journal |last1=Rankin |first1=Catharine H. |last2=Moller |first2=Peter |title=Social Behavior of the African Electric Catfish, Malapterurus electricus, during Intra- and Interspecific Encounters |journal=[[Ethology (journal)|Ethology]] |publisher=Wiley |volume=73 |issue=3 |date=26 April 2010 |doi=10.1111/j.1439-0310.1986.tb00909.x |pages=177–190}}</ref>

When two glass knifefishes (Sternopygidae) come close together, both individuals shift their discharge frequencies in a [[jamming avoidance response]].<ref name="Bullock Hanstra Scheich 1972"/>

In bluntnose knifefishes, ''[[Brachyhypopomus]]'', the electric discharge pattern is similar to the low voltage electrolocative discharge of the [[electric eel]], ''Electrophorus''. This is hypothesized to be [[Batesian mimicry]] of the powerfully-protected electric eel.<ref name="Stoddard 1999">{{Cite journal  |last=Stoddard |first=P. K. |title=Predation enhances complexity in the evolution of electric fish signals |journal=[[Nature (journal)|Nature]] |year=1999 |volume=400 |issue=6741 |pages=254–256 |doi=10.1038/22301 |pmid=10421365 |bibcode=1999Natur.400..254S |s2cid=204994529 }}</ref> ''Brachyhypopomus'' males produce a continuous electric "hum" to attract females; this consumes 11–22% of their total energy budget, whereas female electrocommunication consumes only 3%. Large males produced signals of larger amplitude, and these are preferred by the females. The cost to males is reduced by a [[circadian rhythm]], with more activity coinciding with night-time courtship and spawning, and less at other times.<ref name="Salazar Stoddard 2008">{{cite journal |last1=Salazar |first1=Vielka L. |last2=Stoddard |first2=Philip K. |title=Sex differences in energetic costs explain sexual dimorphism in the circadian rhythm modulation of the electrocommunication signal of the gymnotiform fish ''Brachyhypopomus pinnicaudatus'' |journal=Journal of Experimental Biology |volume=211 |issue=6 |date=15 March 2008 |doi=10.1242/jeb.014795 |pages=1012–1020|pmid=18310126 |s2cid=14310938 }}</ref>

Fish that prey on electrolocating fish may "eavesdrop"<ref name="Falk 2015">{{Cite journal |last1=Falk |first1=Jay J. |last2=ter Hofstede |first2=Hannah M. |last3=Jones |first3=Patricia L. |last4=Dixon |first4=Marjorie M. |last5=Faure |first5=Paul A.|last6=Kalko |first6=Elisabeth K. V. |last7=Page |first7=Rachel A. |display-authors=3 |date=7 June 2015 |title=Sensory-based niche partitioning in a multiple predator–multiple prey community |journal=[[Proceedings of the Royal Society B: Biological Sciences]] |volume=282 |issue=1808 |doi=10.1098/rspb.2015.0520 |pmc=4455811 |pmid=25994677}}</ref> on the discharges of their prey to detect them. The electroreceptive [[Clarias gariepinus|African sharptooth catfish]] (''Clarias gariepinus'') may hunt the weakly electric mormyrid, ''[[Marcusenius]] macrolepidotus'' in this way.<ref>{{Cite journal |last=Merron |first=G. S. |date=1993 |title=Pack-hunting in two species of catfish, Clavias gariepinus and C. ngamensis, in the Okavango Delta, Botswana |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1095-8649.1993.tb00440.x |journal=[[Journal of Fish Biology]] |volume=43 |issue=4 |pages=575–584 |doi=10.1111/j.1095-8649.1993.tb00440.x |bibcode=1993JFBio..43..575M |url-access=subscription }}</ref> This has driven the prey, in an [[evolutionary arms race]], to develop more complex or higher frequency signals that are harder to detect.<ref>{{cite journal |last=Stoddard |first=P. K. |title=The evolutionary origins of electric signal complexity |journal=Journal of Physiology – Paris |year=2002 |volume=96 |issue=5–6 |pages=485–491 |doi=10.1016/S0928-4257(03)00004-4 |pmid=14692496 |s2cid=6240530 }}</ref>

Some shark embryos and pups "freeze" when they detect the characteristic electric signal of their predators.<ref name=Coplin2004>{{cite journal |last1=Coplin |first1=S. P. |last2=Whitehead |first2=D. |title=The functional roles of passive electroreception in non-electric fishes |journal=[[Animal Biology]] |year=2004 |volume=54 |issue=1 |pages=1–25 |doi=10.1163/157075604323010024 }}</ref>

== Evolution and taxonomic distribution ==

In [[vertebrate]]s, passive electroreception is an [[Primitive (phylogenetics)|ancestral trait]], meaning that it was present in their last common ancestor.<ref name="Bullock Bodznick Northcutt 1983">{{cite journal |last1=Bullock |first1=Theodore H. |author1-link=Theodore Holmes Bullock |last2=Bodznick |first2=D. A. |last3=Northcutt |first3=R. G. |date=1983 |title=The phylogenetic distribution of electroreception: Evidence for convergent evolution of a primitive vertebrate sense modality |journal=[[Brain Research Reviews]] |volume=6 |issue=1 |pages=25–46 |doi=10.1016/0165-0173(83)90003-6 |pmid=6616267 |hdl=2027.42/25137 |s2cid=15603518 |url=https://deepblue.lib.umich.edu/bitstream/2027.42/25137/1/0000573.pdf |hdl-access=free }}</ref> The ancestral mechanism is called ampullary electroreception, from the name of the receptive organs involved, [[ampullae of Lorenzini]]. These evolved from the mechanical sensors of the [[lateral line]], and exist in [[cartilaginous fish]]es ([[shark]]s, [[Batoidea|rays]], and [[chimaera]]s), [[lungfish]]es, [[bichir]]s, [[coelacanth]]s, [[sturgeon]]s, [[paddlefish]]es, aquatic [[salamander]]s, and [[caecilian]]s. Ampullae of Lorenzini appear to have been lost early in the [[evolution]] of bony fishes and [[tetrapod]]s, though the evidence for absence in many groups is incomplete and unsatisfactory.<ref name="Bullock Bodznick Northcutt 1983"/>  Where electroreception does occur in these groups, it has secondarily been acquired in evolution, using organs other than and not [[Homology (biology)|homologous]] with ampullae of Lorenzini.<ref name="King Hu Long">{{cite journal |last1=King |first1=Benedict |last2=Hu |first2=Yuzhi |last3=Long |first3=John A. |date=11 February 2018 |title=Electroreception in early vertebrates: survey, evidence and new information |journal=[[Palaeontology (journal)|Palaeontology]] |volume=61 |issue=3 |pages=325–358 |doi=10.1111/pala.12346 |doi-access=free |bibcode=2018Palgy..61..325K }}</ref><ref name="Bullock Bodznick Northcutt 1983"/>

Electric organs have evolved at least eight separate times, each one forming a [[clade]]: twice during the evolution of cartilaginous fishes, creating the electric skates and rays, and six times during the evolution of the bony fishes.<ref name="Kirschbaum 2019">{{cite book |last=Kirschbaum |first=Frank |chapter=Structure and Function of Electric Organs |date=2019 |doi=10.1201/9780429113581-5 |title=The Histology of Fishes |pages=75–87 |place=Boca Raton, Florida |publisher=CRC Press |isbn=978-0-429-11358-1 |s2cid=216572032 }}</ref> Passively-electrolocating groups, including those that move their heads to direct their electroreceptors, are shown without symbols. Non-electrolocating species are not shown.<ref name="Bullock Bodznick Northcutt 1983"/>  Actively electrolocating fish are marked with a small yellow lightning flash [[File:Farm-Fresh lightning.png|15px]] and their characteristic discharge waveforms.<ref name="Kawasaki 2011 pp. 398–408">{{cite book | last=Kawasaki | first=M. | title=Encyclopedia of Fish Physiology | chapter=Detection and generation of electric signals | publisher=Elsevier | year=2011 | doi=10.1016/b978-0-12-374553-8.00136-2 | pages=398–408 |url=https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/malapterurus<!--NOT redundant to DOI-->}}</ref> [[Electric fish|Fish able to deliver electric shocks]] are marked with a red lightning flash [[File:Lightning Symbol.svg|20px]].<ref name="Bullock Bodznick Northcutt 1983"/>

{{clade
|label1=[[Vertebrates]]
|1={{clade
   |label1=[[Lamprey]]s
   |1=[[File:Petromyzon marinus.jpg|80px]]
   |sublabel1='''''End-bud recep.'''''
   |label2=[[Gnathostomata|Jawed fishes]]
   |sublabel2='''''[[Ampullae of Lorenzini|Amp. of Lorenz.]]'''''
   |2={{clade
      |1={{clade
         |label1=[[Chondrichthyes|Cartilaginous fishes]]
         |sublabel1=430 [[myr|mya]]
         |1={{clade
            |1=[[Selachimorpha]] (sharks) [[File:Tiburon portada.jpg|120px]]
            |label2=[[Batoidea]]
            |2={{clade
               |1=[[Torpediniformes]] (electric rays) [[File:Farm-Fresh lightning.png|15px]] [[File:Lightning Symbol.svg|20px]] [[File:Electric ray waveform.svg|50px]] [[File:Fish4345 - Flickr - NOAA Photo Library (white background).jpg|70px]]
               |2={{clade
                  |1=other rays [[File:Mobula mobular.jpg|70px]]
                  |2=[[Rajidae]] (skates) [[File:Farm-Fresh lightning.png|15px]] [[File:Skate waveform.svg|50px]] [[File:Raja montagui2.jpg|70px]]
                  }}
               }}
            }}
         |label2=[[Osteichthyes|Bony fishes]]
         |sublabel2=425 [[myr|mya]]
         |2={{clade
            |label1=[[Sarcopterygii|Lobe-finned fishes]]
            |sublabel1=<!--425 [[myr|mya]]-->
            |1={{clade
               |1=[[Coelacanth]]s [[File:Coelacanth flipped.png|70px]]
               |2={{clade
                  |1={{clade
                     |1=[[Lungfish]]es [[File:Barramunda coloured.jpg|70px]]
                     |2={{clade
                        |label1=[[Amphibian]]s
                        |1=(aquatic salamanders, caecilians; others: '''''lost''''') [[File:Aquatic life (1916-1917) (19559021800) (cropped).jpg|80px]]
                        |label2=[[Mammal]]s
                        |sublabel2='''''(lost)'''''
                        |2={{clade
                           |1={{clade
                              |label1=[[Monotreme]]s
                              |1=(platypus, echidna) [[File:Feeding Platypus (6811147158) (white background).jpg|90px]] [[File:Zaglossus bartoni - MUSE.JPG|80px]]
                              |sublabel1='''''glands in snout'''''
                              }}
                           |2={{clade
                              |label1=[[Cetacea]]ns
                              |1=(Guiana dolphin) [[File:Sotalia guianensis (white background).jpg|80px]]
                              |sublabel1='''''vibrissal crypts '''''
                              }}
                           }}
                        }}
                     }}
                  }}
               }}
            |label2=[[Actinopterygii|Ray-finned fishes]]
            |sublabel2=<!--425 [[myr|mya]]-->
            |2={{clade
               |1=[[bichir]]s, [[reedfish]]es [[File:Cuvier-105-Polyptère.jpg|90px]] [[File:Erpetoichthys calabaricus 1923.jpg|90px]]
               |2={{clade
                  |1={{clade
                     |1=[[sturgeon]]s, [[paddlefish]]es [[File:Atlantic sturgeon flipped.jpg|90px]] [[File:Paddlefish (white background).jpg|90px]]
                     |label2=Most bony fishes
                     |sublabel2='''''(lost)'''''
                     |2={{clade
                        |label1=<br/><!--balance the sublabel's effect on branch positioning, please don't mess with this-->[[Mormyroidea]]
                        |sublabel1='''''[[knollenorgan]]s,<br/><!--there must NOT be a space within the br/ or it won't work here-->[[Electric organ (biology)|electric organ]] '''''
                        |1={{clade
                           |label1=[[Mormyridae]]
                           |1= [[Mormyridae|elephantfishes]] [[File:Farm-Fresh lightning.png|15px]] [[File:Elephantfish spike waveform.svg|50px]] [[File:Gnathonemus petersii.jpg|80px]]
                           |label2= [[Gymnarchidae]]
                           |2= [[Gymnarchus|African knifefish]] [[File:Farm-Fresh lightning.png|15px]] [[File:Knifefish continuous waveform.svg|50px]] [[File:Gymnarchus niloticus005 (white background).JPG|100px]]
                           }}
                        |2={{clade
                           |label1=Silurophysi
                           |sublabel1='''''amp. receptors'''''<!--NOT Amp. of Lorenzini-->
                           |1={{clade
                              |label1= [[Gymnotiformes]]
                              |sublabel1='''''[[Electric organ (biology)|electric organ]] '''''
                              |1={{clade
                                 |label1=S. Amer. knifefishes
                                 |1=[[File:Farm-Fresh lightning.png|15px]] [[File:Elephantfish spike waveform.svg|50px]] [[File:Johann Natterer - Ituí-cavalo (Apteronotus albifrons).jpg|70px]]
                                 |label2=[[Electric eel]]s
                                 |2=[[File:Farm-Fresh lightning.png|15px]] [[File:Lightning Symbol.svg|20px]] [[File:Electric eel waveform.svg|30px]] [[File:Lateral view of Electrophorus electricus.png|100px]]
                                 }}
                              |label2=[[Siluriformes]]
                              |2={{clade
                                 |label1=[[Electric catfish]]es
                                 |1=[[File:Farm-Fresh lightning.png|15px]] [[File:Lightning Symbol.svg|20px]] [[File:Electric catfish waveform.svg|50px]] [[File:FMIB 51852 Electric Catfish, Torpedo electricus (Gmelin) Congo River.jpeg|70px]]
                                 }}
                              }}
                           |label2=[[Uranoscopidae]]
                           |2=[[Stargazer (fish)|Stargazers]][[File:Lightning Symbol.svg|20px]] [[File:Stargazer waveform.svg|50px]] [[File:Uranoscopus sulphureus (white background).jpg|60px]]
                           |sublabel2='''''no electrolocation '''''
                           }}
                        }}
                     }}
                  }}
               }}
            }}
         }}
      }}
   }}
}}

=== Cartilaginous fish ===

Sharks and rays (''[[Elasmobranchii]]'') rely on electrolocation using their ampullae of Lorenzini in the final stages of their attacks, as can be demonstrated by the robust feeding response elicited by electric fields similar to those of their prey. Sharks are the most electrically sensitive animals known, responding to [[direct current]] fields as low as 5 nV/cm.<ref name="shark sense">{{cite journal |last=Fields |first=R. Douglas |title=The Shark's Electric Sense |journal=[[Scientific American]] |date=August 2007 |volume=297 |issue=2 |pages=74–80 |doi=10.1038/scientificamerican0807-74 |pmid=17894175 |bibcode=2007SciAm.297b..74F |url=http://faculty.bennington.edu/~sherman/the%20ocean%20project/shark's%20electric%20sense.pdf |access-date=2 December 2013}}</ref><ref>{{cite journal |last1=Lavoué |first1=Sébastien |last2=Miya |first2=Masaki |last3=Arnegard |first3=Matthew E. |last4=Sullivan |first4=John P. |last5=Hopkins |first5=Carl D. |last6=Nishida |first6=Mutsumi |date=14 May 2012 |title=Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes |journal=[[PLOS One]] |volume=7 |issue=5 |pages=e36287 |doi=10.1371/journal.pone.0036287 |pmc=3351409 |pmid=22606250 |bibcode=2012PLoSO...736287L |doi-access=free }}</ref><ref>{{cite journal |last1=Kempster |first1=R. M. |last2=McCarthy |first2=I. D. |last3=Collin |first3=S. P. |date=7 February 2012 |title=Phylogenetic and ecological factors influencing the number and distribution of electroreceptors in elasmobranchs |journal=[[Journal of Fish Biology]] |volume=80 |issue=5 |pages=2055–2088 |doi=10.1111/j.1095-8649.2011.03214.x |pmid=22497416 |bibcode=2012JFBio..80.2055K }}</ref><ref>{{cite journal |last1=Gardiner |first1=Jayne M. |last2=Atema |first2=Jelle |last3=Hueter |first3=Robert E. |last4=Motta |first4=Philip J. |date=2 April 2014 |title=Multisensory Integration and Behavioral Plasticity in Sharks from Different Ecological Niches |journal=[[PLOS One]] |volume=9 |issue=4 |pages=e93036 |doi=10.1371/journal.pone.0093036 |pmc=3973673 |pmid=24695492 |bibcode=2014PLoSO...993036G |doi-access=free }}</ref>

=== Bony fish ===

Two groups of [[teleost]] fishes are weakly electric and actively electroreceptive: the Neotropical knifefishes ([[Gymnotiformes]]) and the African elephantfishes ([[Notopteroidei]]), enabling them to navigate and find food in turbid water.<ref name="Map of Life"/> The Gymnotiformes include the [[electric eel]], which besides the group's use of low-voltage electrolocation, is able to generate high voltage electric shocks to stun its prey. Such powerful electrogenesis makes use of large [[Electric organ (biology)|electric organs]] modified from muscles. These consist of a stack of electrocytes, each capable of generating a small voltage; the voltages are effectively added together ([[Series and parallel circuits|in series]]) to provide a powerful electric organ discharge.<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]] |date=October 2015 |volume=25 |issue=22 |pages=2889–2898 |doi=10.1016/j.cub.2015.09.036 |pmid=26521183 |doi-access=free |bibcode=2015CBio...25.2889C }}</ref><ref name=Fishbase>{{FishBase |genus=Electrophorus |species=electricus |year=2005 |month=December}}</ref>

=== Monotremes ===

[[File:Platypus electrolocation.svg|thumb|left|upright=1.75|The [[platypus]] is a [[monotreme]] mammal that has secondarily acquired electroreception. Its receptors are arranged in stripes on its bill, giving it high sensitivity to the sides and below; it makes quick turns of its head as it swims to detect prey.<ref name="Scheich 1986"/><ref name="Pettigrew1999"/>]]

The [[monotreme]]s, including the semi-aquatic [[platypus]] and the terrestrial echidnas, are one of the only groups of mammals that have evolved electroreception. While the electroreceptors in fish and [[amphibian]]s evolved from mechanosensory lateral line organs, those of monotremes are based on cutaneous glands innervated by [[trigeminal nerve]]s.  The electroreceptors of monotremes consist of free nerve endings located in the [[mucous gland]]s of the [[snout]]. Among the monotremes, the [[platypus]] (''Ornithorhynchus anatinus'') has the most acute electric sense.<ref name="Scheich 1986">{{cite journal |last1=Scheich |first1=H. |author2=Langner, G. |author3=Tidemann, C. |author4=Coles, R. B. |author5=Guppy, A. |title=Electroreception and electrolocation in platypus |journal=[[Nature (journal)|Nature]] |year=1986 |volume=319 |issue=6052 |pages=401–402 |pmid=3945317 |doi=10.1038/319401a0 |bibcode=1986Natur.319..401S |s2cid=4362785 }}</ref><ref name="Pettigrew1999">{{cite journal |author=Pettigrew, J. D. |title=Electroreception in Monotremes |journal=[[Journal of Experimental Biology]] |year=1999 |volume=202 |issue=Pt 10 |pages=1447–1454 |doi=10.1242/jeb.202.10.1447 |pmid=10210685 |url=http://jeb.biologists.org/content/202/10/1447.full.pdf }}</ref>  The platypus localises its prey using almost 40,000 electroreceptors arranged in front-to-back stripes along the bill.<ref name="Map of Life">{{cite web |url=http://www.mapoflife.org/topics/topic_41_Electroreception-in-fish-amphibians-and-monotremes/|title=Electroreception in fish, amphibians and monotremes |publisher=Map of Life |year=2010 |access-date=12 June 2013}}</ref> The arrangement is highly directional, being most sensitive off to the sides and below. By making short quick head movements called [[saccade]]s, platypuses accurately locate their prey. The platypus appears to use electroreception along with [[mechanoreception|pressure sensors]] to determine the distance to prey from the delay between the arrival of electrical signals and pressure changes in water.<ref name="Pettigrew1999"/>

The electroreceptive capabilities of the four species of [[echidna]] are much simpler. [[Long-beaked echidna]]s (genus ''Zaglossus'') have some 2,000 receptors, while [[short-beaked echidna]]s (''Tachyglossus aculeatus'') have around 400, near the end of the snout.<ref name="Map of Life"/> This difference can be attributed to their habitat and feeding methods. [[Western long-beaked echidna]]s feed on [[earthworms]] in leaf litter in tropical forests, wet enough to conduct electrical signals well. Short-beaked echidnas feeds mainly on [[termite]]s and [[ant]]s, which live in nests in dry areas; the nest interiors are presumably humid enough for electroreception to work.<ref name="Proske 1998">{{cite journal |last1=Proske |first1=U. |author2=Gregory, J. E. |author3=Iggo, A. |title=Sensory receptors in monotremes |journal=[[Philosophical Transactions of the Royal Society B]] |year=1998 |volume=353 |issue=1372 |pages=1187–1198 |pmc=1692308 |pmid=9720114 |doi=10.1098/rstb.1998.0275 }}</ref> Experiments have shown that [[echidna]]s can be trained to respond to weak electric fields in water and moist soil. The electric sense of the echidna is hypothesised to be an evolutionary remnant from a platypus-like ancestor.<ref name="Pettigrew1999"/>

=== Dolphins ===

[[Dolphin]]s have evolved electroreception in structures different from those of fish, [[amphibian]]s and [[monotreme]]s. The hairless [[whiskers|vibrissal]] crypts on the [[Rostrum (anatomy)|rostrum]] of the [[Sotalia (genus)|Guiana dolphin]] (''Sotalia guianensis''), originally associated with mammalian whiskers, are capable of electroreception as low as 4.8 μV/cm, sufficient to detect small fish. This is comparable to the sensitivity of electroreceptors in the platypus.<ref>{{ cite journal |last1=Czech-Damal |first1=N. U. |author2=Liebschner, A. |author3=Miersch, L. |author4=Klauer, G. |author5=Hanke, F. D. |author6=Marshall, C. |author7=Dehnhardt, G. |author8=Hanke, W. |display-authors=3 |title=Electroreception in the Guiana dolphin (''Sotalia guianensis'') |journal=Proceedings of the Royal Society B |year=2012 |volume=279 |issue=1729 |pages=663–668 |doi=10.1098/rspb.2011.1127 |pmid=21795271 |pmc=3248726}}</ref>

=== Bees ===

Until recently, electroreception was known only in [[vertebrate]]s. Recent research has shown that [[bee]]s can detect the presence and pattern of a static charge on flowers.<ref name=Clarke2013>{{cite journal |last1=Clarke |first1=D. |last2=Whitney |first2=H. |last3=Sutton |first3=G. |last4=Robert |first4=D. |s2cid=23742599 |title=Detection and Learning of Floral Electric Fields by Bumblebees |doi=10.1126/science.1230883 |journal=[[Science (journal)|Science]] |year=2013 |volume=340 |issue=6128 |pages=66–69 |pmid=23429701 |bibcode=2013Sci...340...66C |doi-access=free }}</ref>

== See also ==

* [[Active sensory systems]]
* [[Feature detection (nervous system)]]
* [[Magnetoreception]]

== References ==

{{reflist|30em}}

== Further reading ==

* {{cite book |last=Bullock |first=Theodore Holmes |title=Electroreception |date=2005 |location=New York |publisher=[[Springer Science+Business Media|Springer]] |isbn=978-0-387-23192-1 |oclc=77005918 |ref=none}}

== External links ==
{{Commons category|Electroreception}}

* [http://www.elasmo-research.org/education/white_shark/electroreception.htm ReefQuest Centre for Shark Research]
* [http://www.scholarpedia.org/article/Electrolocation Electrolocation on Scholarpedia]
* [http://www.detraditie.nl/sdt_videos/sdt_uk_electroreception_videos.html Video clips of Gnathonemus, Apteronotus, and Ameiurus]

{{Electric fish}}
{{Sensation and perception}}

[[Category:Electroreceptive animals]]
[[Category:Ethology]]
[[Category:Ichthyology]]
[[Category:Senses]]
[[Category:Physiology]]
[[Category:Sensory systems]]