More than 100 electric eels were discovered in one place deep in the Brazilian Amazon River basin, which surprised scientists given these creatures were believed to be quite solitary.
Researchers led by C. David de Santana from the Smithsonian's National Museum of Natural History noticed the eels were, in fact, hunting together. The snake-like creatures were herding small fish called tetras into small packs before shocking them with electricity.
The study was published in Ecology and Evolution on Thursday.
The hunting "pack" of eels' behavior stunned the scientists. "This is an extraordinary discovery," de Santana said. "Nothing like this has ever been documented in electric eels."
Their discovery reshapes the thoughts that eels are solitary creatures. According to de Santana, only nine fish species hunt in groups, compared with many more mammals who use this technique for hunting.
The type of electric eel the team observed in the Iriri River in the Brazilian state of Pará is called Volta and is capable of producing 860-volt electric shocks.
De Santana broke down what those numbers mean when he explained "[...] so in theory if 10 of them discharged at the same time, they could be producing up to 8,600 volts of electricity."
"That’s around the same voltage needed to power 100 light bulbs."
Today, a new paper in Ecology and Evolution challenges what researchers know about eels’ supposed loner behavior. https://t.co/BM9sIbIeOC— Smithsonian Magazine (@SmithsonianMag) January 14, 2021
The team's next steps include measuring these simultaneous shocks, which may bring about a few zaps to the researchers themselves — but as de Santana has experienced before, these electric shocks are certainly stunning, but only last about two-thousandths of a second. Don't be fooled though, it's still enough to create painful muscle spasms and knock a human off its feet.
During its latest research deep in the Amazon basin, the team noticed the Volta electric eels would hunt at twilight, starting off by swimming together in a large circle. They would corral the tetra fish into smaller and smaller shoals, moving the fish from deeper parts of the river towards the shallows.
Here, the eels broke off in groups between two and 10 and moved in closer to the fish to jointly launch an electric shock. These shocks sent the fish flying into the air and when they landed back in the water they were motionless from the stun. At this stage, all the eels would gather to feast on their prey.
This daily ritual took around one hour, as de Santana and his team noted.
"This is the only location where this behavior has been observed, but right now we think the eels probably show up every year," de Santana said. "Our initial hypothesis is that this is a relatively rare event that occurs only in places with lots of prey and enough shelter for large numbers of adult eels."