Electric eels think that we were alone in that they were not alone.
In a small lake in the Amazon River Basin in Brazil, scientists have recorded for the first time the fish not only live together, but are actively working together to forage, and bring their prey down for.
There is also evidence that the strategy is working. Bumper volta’s electric eels (Electrophores voltai, Not a true eel, but a type of knife tip) found in the lake, many more than 1.2 meters (4 ft) in length.
“This is an extraordinary discovery,” said ichthyologist Carlos David de Santana of the Smithsonian Institution’s National Museum of Natural History. “Nothing like this has ever been documented in electric eels.”
Not much is known about Volta’s electric eels. The fish was recently discovered in a lake on the banks of the River Iiri, and last year was officially described and recognized as a distinct species. But it packs a punch, capable of discharging a single shock of over 860 volts – more powerful than any other electric eel on record.
De Santana and his team first observed hunting for electric eels in a group in 2012. More than 100 individuals worked together with the herd and killed the prey to feed the entire shoal. But one observation was not enough to classify prey as normal behavior.
In 2014, the team returned and even got Volte’s electric eels, so they got the job of watching and recording the animals. After observing over 72 hours of continuous observation, he saw electric eels engage in five more prey. Not only was this sufficient to classify this behavior as normal, but it allowed researchers to observe and record how these “social prediction events” occur.
During the day and night, electric eels mostly rested. At dusk and dawn, in the twilight hours, the electric eel instigated itself to hunt. This, as the team noted in their paper, is unusual: usually, Volta’s electric eels are only seen for foraging at night and singles.
The difference here is striking. On each occasion, more than 100 individual electric eels gathered and began swimming in circles, effectively forming groups of small fish, mostly chaotic, as a “hunting ball” that they slowly lived in shallow waters.
Then, once the hunting ball was nowhere to go with the tightening, by 10 the electric eels surged forward and launched a powerful joint strike, stunning the prey – which would jump out of the water before falling down, insensitive.
“If you think about it, a person of this species can produce discharges of up to 860 volts – so in theory if 10 of them are discharged at the same time, they can produce up to 8,600 volts of power. Can produce, “De Santner said. “This is around the same voltage required to power 100 light bulbs.”
Once the victim was stunned, the SHO could comfortably go in and have food.
Each hunt, the team found, took around an hour and involved five to seven electrical attacks.
“It is common for mammals to hunt in groups, but it is actually quite rare in fishes,” de Santana said. “There are only nine other species of fish known to do this, which makes this discovery truly special.”
Nevertheless, while hunting may be common, the team still believes that they can be very rare. In his interview with the locals, the congregation and hunting behavior of electric eels was not mentioned. Therefore, whether electric eels gather for hunting or solos may depend on the right conditions, such as high prey abundance, and specific locations with shelter for large numbers of these fish.
While much is still unknown, the team believes electric eels will likely return to the lake on an annual basis. He has launched a citizen science project called Projeto Porquay, where locals can log comments; Those data can prove invaluable. And the team plans to return to the location in hopes of seeing the animals again.
“In addition to trying to locate additional populations of eels involved on group foraging, our future field- and laboratory-based study of social forecasting in electric eels, focusing on the links between populations, social structures, genomics, and electrogenesis Will investigate, “he wrote in his paper.
“In summary, this case provides a unique perspective for future studies on the evolutionary gaps between predator and escape strategies among vertebrates.”
The research has been published in Ecology and development.
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