Impurest's Guide to Animals #112 - Electric Eel

Finally the grim weather gripping the UK has finally begun to lift just in time for the spring field surveying season. This week we trade in the toxins of the Koppie Foam Grasshopper for an electrical issue. Hope you guys enjoy.

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Issue #112 – Electric Eel

Kingdom – Animalia

Phylum – Chordata

Class – Actinopterygii

Order – Gymontiformes

Family – Gymnotidae

Genus – Electrophorus

Species – electricus

Related Species – Despite appearances Electric Eels are not related to true eels and are instead a member of the Knife Fish family. (1)

Range

A Shocking Development

Electric Eels are the largest members of the Knife Fish family, reaching a length of 2m and a weight of 20kg, although slightly larger specimens have been recorded. Unlike the majority of fish, the Electric Eel is an obligate air breather, and has to surface every ten minutes to take a gulp of atmospheric air (2). Electric eels are almost blind, not being able to distinguish anything more than the difference between light and shadow, and instead navigate via echolocation and electroreception. To aid in navigation all the eel’s vital organs are located in the front 20% of the fishes body, with the remaining 80% lined with three electric organs; the Main Organ, the Sach’s Organ and the Hunter’s Organ.

When used solely for the navigation, electrical discharges are emitted by the Sach’s Organ and are kept at a low level (around 10V and 25Hertz). When a potential prey item disturbs the electrical field around the Electric Eel, the fish opens ionic channels from the Sach’s Organ to the main and Hunter’s organs, stimulating the electricity producing cells and creating a short yet powerful electrical discharge of over 800V and 1 ampre of current, stunning or even outright killing their prey. In addition to attack the electrical discharges are used in defence, with an adult electric eel able to cycle intermittent electrical shocks every few seconds for up to an hour (3).

During the breeding season male electric eels build nests of saliva, before attracting the female to his territory by modulating the electrical discharges from the Sach’s Organ. After laying the eggs in the nest the female eel leaves, and the male aggressively defends both the eggs and newly hatched fry from predation until their electrical organs develop enough to create their own electrical discharges.

Ecology 101: An Introduction to Environmental Mechanics #13 – Electroreception in Nature

In 1750, history states that the well renowned scientist Benjamin Franklin gathered the electrical energy of a thunderstorm using a kite with a key attached, becoming the first person to harness atmospheric electrical energy. However long before 1750, the natural world had harnessed the power of electricity for communication, navigation and defence. The organisms that can detect and harness electricity are referred to as being electro-receptive and are mostly amphibious or aquatic due to the increased conductive abilities of water.

The most basic electro-receptive ability is electro-location, which is where an animal can detect biological and geological electric fields. A number of fish; such as sharks, sturgeons, lungfish and gars, are able to detect electrical fields, effectively using them to locate hard to find prey and evade obstacles. In addition to fish, both the Platypus (Ornithorhynchus anatinus) and the Western Long-beaked Echidna (Zaglossus bruijini) can also detect electrical fields, with the latter being one of the few terrestrial examples of electroreception, although it has far less electroreceptors than the Platypus.

The actual use of electrical fields is far rarer than their detection, with only a few groups such as the Knife fish, Elephant Nosed Fish, Torpedo Rays and a few others actively creating electrical fields for navigation. The majority of these fields are too weak for predatory usage, often peaking at an output of 1-3V, and are labelled as ‘weakly electric fish’. Despite their limited output these fields are useful for navigation and communication, with most of these ‘weakly electrical fish’ living in murky water or are nocturnal. In some instances such electrical fields can be used to deceive predators, with the Bluntnose Knifefish (Brachyhypopomus sp) mimicking the passive discharge pattern of the electric eel to dissuade larger fish from attacking it.

Only three groups of fish (Knifefish, Torpedo Rays, Electrical Catfish) create active electrical discharges for predatory reasons. While the electric eel is the most well-known of these ‘strongly electric fish’, it is the Torpedo Rays that produce the deadliest discharges, partially due to the greater conductivity of salt water in comparison to fresh water. While the voltage from the ray is much lower, peaking at 200V, the discharge reaches a current of 30amperes, allowing it to stun larger prey and predator species.

While Benjamin Franklin may have been the first person to harness atmospheric electricity, it was the ancient Egyptians who were the first people (on record) to use electricity. The Electric Catfish (Malapterurus electricus) was well known to the Egyptians, with carvings of the fish on the walls of tombs dating back 5000 years. Fishermen on the Nile had a healthy respect for the fish referred to in ancient texts as ‘the Thunderers of the Nile.

Bibliography

1 -www.arkive.org

2 - Johansen, Kjell (1968). "Gas Exchange and Control of Breathing in the Electric Eel, Electrophorus electricus". Z. Vergl. Physiologie (Springer Berlin / Heidelberg) (Volume 61, Number 2 / June, 1968): 137–163.

3 – Catania, Kenneth C. (2015-10-29). "Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey". Current Biology25: 1–10

4 – Stoddard, P. K. (1999). "Predation enhances complexity in the evolution of electric fish signals".Nature400(6741): 254–256

Picture References

1 - http://cdn1.arkive.org/media/52/5265073B-F144-463E-ABD8-EE9D0EED8CF4/Presentation.Large/Electric-eel-in-habitat.jpg

2 - http://images.nationalgeographic.com/wpf/media-live/graphic/map-electric-eel-160-20040-cb1273160910.gif

3 - http://www.aqua.org/~/media/Images/Animals/Electric%20Eel/animals-electriceel-slide1-web.jpg

4 - http://animal.memozee.com/ArchOLD-4/1126845155.jpg

5 - https://upload.wikimedia.org/wikipedia/commons/b/b5/Malapterurus_electricus_1.jpg

Talk about an electrifying issue, all this discharge is bound to cause an overload somewhere down the line. As for clues on next week’s animal; well it can fly, is nocturnal, uses echolocation and eats fruit…sounds simple right. Well we’ll see next week, but until then critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary.

Many Thanks

Impurest Cheese

@cbishop, @laflux, @ostyo, @wildvine, @luna_joestar, @xwraith, @cgoodness, @ms-lola,@dboyrules2011,@quinnofthestoneage,@scavengerfist,@rocketraccoonthingy,@black_wreath,@captainmarvel4ever,@spareheadone,@cpt_nice,@risingbean,@pipxeroth,@theik2,@avatar_of_green, @tsciallsolle3451, @galactic_1000, @tazirai and @juiceboks

Here's the newest IGTA issue...free of charge

Huh, and I was just thinking about this song today.

Nonetheless, great choice this week and I'll be looking forward to what the next one turns out to be.

@juiceboks: Well you know what they say about great minds...

Thanks for the comment

The Amazon, where you have to turn into a electric pokemon to survive

@impurestcheese: When I first found out Electric eels where obligate air breathers I was like "holy shit that's so cool". Nice work as always :)

@cgoodness: Pretty much, but nothing bothers the Electric Eel more than once

@laflux: Yeah there gills are gone replaced by extra electric organs apparently

@impurestcheese: I should probably Google search this myself, but I figure you've already done the research, soooo... is the electric discharge from an eel enough to harm or kill humans?

@cbishop: It takes 700 Mega Amps to stop arterial fibrillation over a period of 30 ms to stop a healthy human heart. That said the eel does have the juice to stun an adult human and cause temporary numbness and paralysis, although this can cause drowning if the human is out of their depth in the second largest river in the world. Assuming you don't drown the discharge is likened to a 'stun bite' from a shock-prod, and is only temporary.

@impurestcheese: So the shock on its own shouldn't kill, but it would hurt like heck. Yeeowtch! :}

Why doesn't it shock itself or its offspring accidentally?

@cbishop: Yeah they can really pump out the discharge

@impurestcheese: Cool! :)

@avatar_of_green: Well it has to do with the eel being submerged in water, any electrical discharge radiates out across a water body weakening the current output. With the eel's output already low (1amp) and so short (2ms) a large eel risks very little when discharging. In addition the vital organs are all insulated with electro-resistant tissue that protects even the smallest of fry

@cbishop: Cool indeed, there is an electric eel (Miguel Wattson) with its own twitter page. Every times he produces electricity a random tweet goes out, assuming the digital fuse box managing his tweets per discharge doesn't break. If it does then the eel would produce so many tweets that the internet would be overloaded

@impurestcheese: Weirdness. :}

@cbishop: Just a bit

For anyone reading I am open for some request issues if you can think of any. Can't wait to see what you ask about.

Hammerhead Sharks must be the torpedo ray's worst nightmare...if it can survive the shocks.

@ostyo: Predators generally leave Torpedo Rays alone due to their size and defences. Hammerheads ocassionally have a go, but ultimately stuff like Stingrays are easier prey

Coati, civet, spectacled bear, kodiak bear, horridus, and whatever those monkey-things are that have the really big eyes and suction-tip-looking fingers. :)

Eels are exciting!

Huh, was not aware it wasn't a real eel, cool.

@cbishop: Hold on there hosd, we covered the coati already.

@theik2:They truly are

@pipxeroth: Yep it's one of those sneaky faux eels

These guys are bad.

They create supervillains. :(

@black_wreath: The electric eel union would like to point out that was one time during a drunken party

What?

A creature I've heard of?

@spareheadone: It happens occasionally...

@impurestcheese: first time for me : )

@spareheadone: True it's back to the regular weirdness next week

Cool article bro! Mind if I share this off-site?

@impurestcheese: I couldn't remember whether you had or not- I didn't go looking through the bestiary first. If you've done it, just knock it off the list of suggestions. ;)

@cbishop: Hmm well from Issue 115 onwards I currently have no animals selected, pretty sure they can fit in their

@scavengerfist:What do you mean by 'share this off site'?

Related Species – Despite appearances Electric Eels are not related to true eels and are instead a member of the Knife Fish family. (1)

Yeah, a typical peeve I have with animal names is how misleading at times they can be.

An interesting trivia which I happen to stumble upon Wikipedia after reading your article:

• Apparently some aquarium owners got their electric eel to post something on twitter whenever it makes an electric discharge (The electric discharge generates the signal for the computer to post on twitter, of course) - http://www.timesfreepress.com/news/life/entertainment/story/2015/jan/16/snap-crackle-tweet-tennessee-tech-helps-aquarium-eel/282710/
• The twitter account is here - https://twitter.com/EelectricMiguel

@tsciallsolle3451: Yeah tell me about all the natural world misnomers. I was talking about that tweeting eel to @cbishop yesterday. great minds..G

Wow, that's really impressive !

@quinnofthestoneage: It is indeed, thanks for the comment

Ah. Anyone up for a Pikachu vs Electric Eel CaV? :P

Nice one cheese. :-D

@rocketraccoonthingy: You mean Eelektross the pokemon with no weaknesses

Knife fish are so appealing to me. I'm going to look into them further.

I'm not surprised the ancient Egyptians harnessed electricity first; at least the first to have documented it. Another tidbit to keep in my pockets, compliments of these blogs.