The Absurd Story That Inspired Electric Eel Research
5–8–17
Alright team, no excuse for my tardiness on this one, so here we go.
Today we are entering the mysterious world of electric eels.
I was inspired by this ridiculous gif:
…and I got to thinking: electric eels are pretty dope. I had learned of them throughout my life, knew they existed, but really didn’t know much else beyond that. So here we are, about to learn together.
Let’s start simple: wtf is going on in this gif? Turns out, it was part of a scientific study out of Vanderbilt whose inspiration might be one of the most absurd stories I have ever read.
Back in the 1800’s, Alexander von Humboldt — world renowned naturalist, archaeologist, and guy with a great name — was exploring South America in pursuit of electric eels to study. Him and his travel companion Aimé Bonpland had managed to capture a single eel on their trip, but they were too afraid (read: soft) of the animal to handle it in a method amenable to research. Disappointed by their results and searching for some guidance re:handling electric eels, the two traveled to Venezuela, where the natives were known for their eel hunting. They happened to visit at the perfect time of year, as it was dry season, and many eels go stuck in small wading pools as more shallow streams dried up.
The natives quickly befriended Humboldt and Bonpland and took them to a local reservoir of slimy water where a stream had mostly dried up and a swarm of eels (bonus FF: a group of eels is called a swarm) had gotten stuck. Eels are rather finicky creatures, as they like to bury themselves into the muddy slime, rendering traditional fishing nets useless. The natives knew better, however, declared that they would fish with the horses.
So how did this work? They took a team of horses and a small barren of mules (more grouping terms!) and forced them into the water where the stamping of the horses aggravated the eels and drove them out of the slime. What happened next shocked (heh, no pun intended) Humboldt and Bonpland: the eels swam to the surface of the water and up the horses/mules legs where they pressed against their skin and discharged their electric charge. A strange battle ensued, as the horses tried to escape their muddy torture chamber while the natives pushed back at them with sharp bamboo stalks like a shitty game of Operation. Multiple horses were downed by the shocks, struggling in the water after being shocked repeatedly in the belly and on their heads, eventually drowning. Eventually the eels collapsed, exhausted from the attack, and drifted toward the edge of the mud pool. After the surviving horses cleared, the locals waded into the water with harpoons attached to little ropes.
Okay, at this point you would think “hey, that’s pretty clever, in a really sad, torturous, and Darwinian way.” And you’d be almost right, because even after all that, they made the mistake of using the same ropes attached to the harpoons multiple times. So the first eel they caught with the fresh and dry harpoon/rope was no problem to pull back in. Future eels caught with the wet rope used whatever energy they had left to shock the harpoon, which traveled up the rope to the natives pulling them in. Nevertheless, they persisted, and pulled more eels back in. Eternally grateful, Humboldt and Bonpland collected their eels and went on their merry way.
So how does this relate to the gif? Well, it all hinges on Humboldt’s legendary account of the eels swimming up and out of the water — for 200 years since then, no one had seen eels jumping out of water and shocking things…until now.
Ken Catania at Vanderbilt sought to settle this myth once and for all — can eels jump out of the water to shock their prey? No one had seen this happen for literally hundreds of years, why believe it? Well, it documented that eels can shock and kill prey, but if it discharges when it’s floating around in the water, the current radiates outward from the eel in all directions, decreasing the amount of “shock” one would feel. Sure, it’s enough to temporarily stun a small fish, but not really enough to mess with a larger predator (like a human, for example, “Michael Faraday, who, after some (quite literally) hands-on experiments with electric eels in 1838, wrote: “When one hand was in the water the shock was felt in that hand only, whatever part of the fish it was applied to; it was not very strong, and it was only in the part immersed in water.”
Surely, there must be a more powerful way for eels to shock prey? Well, one day Catania was fishing for one of his eels with a net when it became disgruntled, swam up the net handle, and delivered a sizable shock to the Ken. Shocked (heh, puns), and inexplicably aroused (curiously aroused, you perverts), he set up this experiment where he wired tiny LEDs into a prosthetic arm to demonstrate the eel defense strategy visually. Voila, that is the source of your gif.
Now, for some interesting observations: Notice how the eel presses its chin firmly on the arm. That’s where it is discharging from, which allows it to maximize the shock. In doing so, it is creating a short circuit between the animal and its threat, giving the current nowhere to go but into the creature being shocked. This is so precise that the eel can even stop shocking within milliseconds of losing contact at its chin.
So how much electricity is being delivered? Turns out these bad boys can deliver volleys of shocks well over 200 volts. How do they deliver the shock? They literally have electricity organs. To be specific, they have three pairs of abdominal organs, taking up 4/5 of their body, which produce electricity: the main organ, the Hunter’s organ, and the Sach’s organ. Fundamentally they all work the same way — by creating a huge ion gradient and releasing it all at once. What’s really cool is that although these different organs all act the same basic way and produce the same electric response, they can be used for different functions. Through the use of various combinations of these organs, Catania and colleagues have demonstrated that the electric eel “is a battery, Taser, remote control, and tracking device, all in one. With different kinds of pulses, it can make a prey animal twitch and so give away its presence, it can paralyze its victim by forcing all its muscles to contract, and it can monitor the movements of the stiffened targets. And when it wants to take down a really big target, like a crayfish, it can curl its body to deliver twice the shock for no extra effort.”
TL;DR don’t mess with eels.
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