Natures wonders: some eels hunt in packs (Introduction)

by David Turell , Friday, January 15, 2021, 02:16 (1198 days ago) @ David Turell

In a deep lake:

https://www.sciencedaily.com/releases/2021/01/210114163927.htm

"Deep in the Brazilian Amazon River basin, scientists discovered a small, river-fed lake filled with more than 100 adult electric eels. Researchers witnessed the electric eels working together to herd small fish into tightly packed balls. Groups of up to 10 eels periodically split off to form cooperative hunting parties. Those smaller groups then surrounded the prey and launched simultaneous electric attacks. The findings overturn the idea that these serpentine fish are exclusively solitary predators.

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"the researchers witnessed the eels working together to herd small fish called tetras into tightly packed balls. Then groups of up to 10 eels periodically split off to form cooperative hunting parties, not unlike packs of wolves or pods of killer whales. Those smaller groups then surrounded the prey ball and launched simultaneous electric attacks, stunning the tetras into submission.

"'This is an extraordinary discovery," de Santana said. "Nothing like this has ever been documented in electric eels."

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"'Hunting in groups is pretty common among mammals, but it's actually quite rare in fishes," de Santana said. "There are only nine other species of fishes known to do this, which makes this finding really special."

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"In these twilight hours, the eels started interacting with each other and then began swimming in a large circle. This churning circle of electric eels corralled thousands of the 1-to-2-inch tetras into tighter and tighter shoals. The researchers watched the group herding the concentrated tetras from the deeper end of the lake -- around 12 feet deep -- to shallow, 3-foot deep waters.

"With the tetras trapped by the main group, de Santana says bands of two to 10 eels would separate, move in closer and then launch joint electric attacks on the prey ball. The electric shocks sent the tetras flying out of the water, but when they splashed down the small fish were stunned and motionless. Finally, the attacking eels and their compatriots easily picked off their defenseless prey. According to de Santana, each dawn or dusk hunting ritual took around one hour and contained between five to seven high-voltage attacks."

Comment: thnis obvious cooperation will delight dhw.