Electric eels are not what we thought they were.
In a small lake deep in the Amazon River basin in Brazil, scientists have for the first time recorded the fish not only living together, but also working together for fodder and prey.
There is also evidence that the strategy works. In many of Volta’s electric eels (Electrophoresis Voltoy, Not one The real eel But one species of swordfish) was found living in the lake, many 1.2 meters (4 feet) long and lush.
“This is an extraordinary discovery.” ichthyologist Carlos David de Santana said National Museum of Natural History by the Smithsonian Institution. “Nothing like this has been documented in electric eels.”
Not much is known about Volta’s electric eel. This fish was recently discovered in a lake across the Irri River, officially described last year and recognized as a unique species. But it does build a punch, which can emit a shock above 860 volts – more powerful than any other electric pole on the record.
De Santana and his team first observed electric eels hunting in 2012 in a group. More than 100 individuals seemed to work together to raise flocks and kill prey, thus feeding the entire shoal. But one observation is not enough to classify hunting as normal behavior.
In 2014, the team came back and still found Volta’s electric eels, so they came to the job of caring for the animals and registering them. During 72 hours of continuous observation, electric eels were found to be engaged in five more hunts. Not only was this sufficient to classify behavior as normal, it also allowed researchers to observe and record how these “social predation events” occur.
During the day and night, the electric eels often rested. Twilight and dawn, the Twilight, Electric eels provoked themselves to hunt. This, the group mentioned in their paper, is unusual: in general, Volta’s electric eels are found only at night and in solitude.
The difference here is striking. In each case, more than 100 individual electric eels were collected and began to swim in circles, effectively breeding groups of small fish. Saracens, They gradually turned red in shallow water to become a “prey ball”.
Then, as soon as the ball of prey became so tight that it could not go anywhere, the 10 electric eels moved forward and began a powerful collective strike.
“If you think about it, a person of this race can generate up to 860 volts of emissions – so in theory if 10 of them are discharged at once, they could produce 8,600 volts of electricity.” D Santana said. “It’s around the same voltage needed to turn on 100 light bulbs.”
When the prey is stunned, the shoal can enter and feed at leisure.
Each hunt, the team found, took an hour and consisted of five to seven power strikes.
“Hunting in groups is very common among mammals, but it is actually very rare in fish.” D Santana said. “There are only nine other fish left to do this, which makes this discovery even better.”
Nevertheless, the team still believes that while hunting is normal, they can be very rare. In their interviews with local people, the council and hunting behavior of electric eels were not mentioned. Therefore, whether electric eels hunt or go it alone depends on the right prey, i.e. have more prey in abundance, and specific locations where these fish have a greater number of habitat.
Although not much is known yet, the team believes electric eels may return to the lake on an annual basis. They started a citizen science project The war plan, Locals can record observations; That data would be invaluable. The team has planned to visit the place again and again in the hope that we will take care of the animals again.
“In addition to trying to find additional populations of group hunting eels, our future field and laboratory-based studies will explore the social predation of electric eels on population, social structures, genetics, and electrogenesis,” they wrote in their paper.
“In short, this case provides a unique perspective on future studies of the evolutionary gap between predatory and escape tactics among vertebrates.”
Research has been published Ecology and evolution.