A recent investigation has discovered a fascinating fact about electric eels. It turns out that these fish are more potent when they jump out of the water to attack their predators. Dr. Kenneth Catania, made the discovery inspired on an 1800 story by Alexander von Humboldt.
A fun fact about electric eels is that, despite their name, they aren’t eel fish. They belong to the knife fish family, most commonly found in the tropic and South America.
These species is characterized by having long bodies which allow them to swim and move around their environment. Knifefishes are only found in fresh waters and mostly come out at night time.
Their main characteristic is their electrical attack and defense, their bodies commonly grow up to 2 meters and weigh around 20 kg. The pigmentation on the eel’s body is dark on the back and yellow on the belly.
Electricity runs in the eel’s body thanks to the three pairs of organs located in their abdomen, known as the central organ, the Hunter’s organ and the Sach’s organ. Eels are capable of generating low voltage discharges and high energy discharges.
Proving an old tale
Humans have long investigated eels, even Darwin and Faraday studied eels in their time. Explorer Alexander von Humboldt was also fascinated by eel’s, so much he wrote a story about an encounter between eel’s and horses.
The story was written over 200 years ago and has been seen as a tale the explorer told among his findings. In the Story Humboldt described how while in the Amazon, local fishermen helped him find electric eels for a study.
To collect the eel’s fishermen and Humboldt arrived at a lake containing eel’s with horses and mules, to find themselves in a fight between these aquatic animals and gigantic beasts. At the end of the story Humboldt described how horses passed out and drowned for the eel’s attack.
Now Dr. Kenneth Catania from the Vanderbilt University has proven that explorer Humboldt was right, and his tale was real.
“ I certainly thought it was a crazy story when I did consider it, but I don’t anymore. At this point I don’t think he exaggerated one bit,” Catania told the Christian Science Monitor.
Dr. Catania made the discovery while working with one of his eel’s when suddenly the story came to his mind and he decided to perform an experiment involving these aquatic animals and an alligator puppet.
The experiment consisted of measuring the amperage and voltage of the eel’s discharge, Catania grabbed a plastic alligator puppet and inserted LED lights inside of him, that would light up in the case of discharge.
For Dr. Catania’s surprise, when he inserted the puppet inside the eel’s aquarium the fish jumped and discharged a high voltage energy into the puppet, having the LEDs light up.
This behavior is easily explained, eels use their electric discharges as a protection against their predators, but underwater their energy is not as high. During the dry seasons in the Amazon, for example, eel’s are often found with low levels of waters and without anywhere to go, that’s why their instinct has them jumping and attacking predators.
“Recognizing that the voltage imparted increases with the height of the eel coming out of the water explains how this could have evolved. It also fits so nicely with the successive stages required for selection,” said Catania to the Monitor.
Dr. Catania’s findings can be found in the Proceedings of the National Academy of Science of the United States of America.
Source: PNAS