Evolutionary Mash-up: Electric Eel

There has been a number of occasions in my life where I wished I had the ability to shoot electricity from my fingers. Inspired by the Emperor (or Sheev Palpatine for you star wars fanatics out there) from the Star Wars movie series, shooting electricity from my hands would come in handy when I need to exact revenge upon my enemies. Alright, so as not to get arrested, maybe just to zap those pesky house flies would make that ability useful! Technically, humans and all animals with a nervous system have electric currents that travel all throughout their bodies controlling muscle movement and other behaviors. But very few animals can use those electric currents from their nervous system to physically shock others around them. Step aside Emperor Palpatine, one of these animals does not need the force to discharge electricity with a voltage of up to five times that of an average household electrical outlet! Make way for this master of defense, the electric eel.

photo of room full of toys
Photo by Alex Kremer on Pexels.com

The electric eel takes up residence in the Northeastern South American waters and ranges in length between 6 and 8 feet. Despite living solely in the water, these eels are air breathers and will surface frequently for the oxygen they need to live. Shockingly, the electric eel is not even an eel and is more closely related to catfish and carp than it is to other eels.

Next to discuss its shock-producing super powers. The electric eel contains special electric organs that contain up to 6,000 specialized disc-shaped cells called “electrocytes.” It is estimated that the electrocytes make up about 80% of the eel’s body. These cells run along the outside of the eel’s body and line up in such a way as to create a circuit. These electrocytes hold an electric charge created from the flow of potassium and sodium ions across the cell membrane. The specialized cells can hold just enough charge to create a light shock or they can ramp up the charge and create a stunning burst of electricity.

IMG_20190420_161615421
Picture of an electric eel taken by myself at the Loveland Living Planet Aquarium in Draper, Utah.

Now for the method of attack. Using a very light electric charge, the electric eel can navigate its surrounding area with a small discharge. The eyesight of the electric eel is sub-par so this navigation tactic comes in handy. Once the eel senses prey or predators nearby, it can unleash a charged up electric shock. These electrical blasts, with a strength of up to 650 volts, are enough to deter predators. Research also shows that these stronger discharges give the eel the ability to control the movement of its prey. The electric eel can let loose high frequency volleys of high powered electricity to induce tetanus (which is full body muscular contraction) in its prey. Or, if the prey is hiding, the eel can unleash short bursts of high powered electricity causing its prey to undergo involuntary spasms. This causes the prey to give away its position and then the eel can follow-up with a high frequency blast, causing tetanus, and finally go in for the kill. The electric eel is a master puppeteer using electric discharges as the strings controlling its unfortunate prey.

body of water
Photo by Marcus Bergh on Pexels.com

Finally let’s talk about the evolutionary mash-up. Last time we left our Northern Lampfish a (near) defenseless prey actively being eaten by anything from birds to whales. Now, let’s add some electrocytes to our lampfish and see how it fares. Assuming we leave the lampfish the same length, packing in as many electrocytes as we can will give the lampfish a much needed form of defense. If we made the lampfish longer, it could potentially have more electrocytes and a bigger circuit giving it a stronger discharge. Predators will soon learn to steer clear. But some predators rely heavily on the lampfish for food and are much bigger than the lampfish, so bursts of electricity may not be enough to discourage them from attacking. Also, if the lampfish were to develop the adaptation of electric discharge, it may need a more robust diet to account for the extra sodium and potassium needed to create defensive burst of electricity. Stay tuned as next week we give our Northern Lampfish a new adaptation to help boost its chances of survival through both obtaining prey and fighting off predators!

 

If you read this whole blog post, you are my hero! Thanks for reading. Please feel free to leave me a comment and feedback below. Also, let me know if there is any particular science topic you would like me to look at “through green tinted glasses” and I will write about it.

 

Works Cited:

https://www.sciencefocus.com/nature/how-do-electric-eels-generate-voltage/

https://www.nationalgeographic.com/animals/fish/e/electric-eel/

https://science.sciencemag.org/content/346/6214/1231

National Geographic: Animal Encyclopedia

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