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Electric Eels Use Their High-Voltage Shocks to Locate Prey

Electric eels use special electricity-emitting organs to stun their prey, and a scientist recently discovered they use these same mechanisms to locate their food in the dark. A study published this week in Nature Communications [PDF] illustrates how these nocturnal creatures use energy fields to “electrolocate” their prey as well as paralyze them with a charge of up to 600 volts.

Ken Catania, a neurobiologist at Vanderbilt University, conducted a series of laboratory experiments in which he observed this shocking behavior in action. He presented the eels with anesthetized fish, blocked from the predators' electroreceptors with plastic bags. When Catania forced the fish to twitch with an electrode, the eel emitted its electrical attack. But after that, it was stumped. The eel lunged towards the movement in the water but made no attempt to devour the fish.

Things got even more interesting once Catania introduced an electrically conductive carbon rod to the tank. After releasing its charge, the eel initially moved towards the direction of the fish only to change its mind and dart towards the rod instead, wherever it had been placed. When Catania moved the rod onto a rotating wheel and removed the fish from the tank entirely, the eel was further confused, writhing to suck up the rod that it perceived to be its prey.

This behavior suggests that electric eels are able to simultaneously use their electric charge as a predatory attack and a tracking system. Catania published a separate study in Science last year that showed how an electric eel’s shock can stimulate its prey’s motor neurons and cause involuntary muscle spasms. After a couple of electric volleys, the helpless fish will have revealed its location before the eel goes in for the kill. The eel sucks up the prey within milliseconds of the attack, which we now know it does by using its high-voltage charge to pinpoint its exact location.

These recent findings place electric eels in the same league as bats, sharks, and other creatures who use a type of “sixth sense” to locate their prey. Sharks and rays can sense the electric fields emitted by other creatures, while bats and some whales use sonar to detect reflected sound. But eels are the only creatures whose locating sense doubles as a weapon, making them even more awesome (or terrifying) than we previously realized. 

[h/t: National Geographic]

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Big Questions
Why Do Cats Freak Out After Pooping?
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Cats often exhibit some very peculiar behavior, from getting into deadly combat situations with their own tail to pouncing on unsuspecting humans. Among their most curious habits: running from their litter box like a greyhound after moving their bowels. Are they running from their own fecal matter? Has waste elimination prompted a sense of euphoria?

Experts—if anyone is said to qualify as an expert in post-poop moods—aren’t exactly sure, but they’ve presented a number of entertaining theories. From a biological standpoint, some animal behaviorists suspect that a cat bolting after a deposit might stem from fears that a predator could track them based on the smell of their waste. But researchers are quick to note that they haven’t observed cats run from their BMs in the wild.

Biology also has a little bit to do with another theory, which postulates that cats used to getting their rear ends licked by their mother after defecating as kittens are showing off their independence by sprinting away, their butts having taken on self-cleaning properties in adulthood.

Not convinced? You might find another idea more plausible: Both humans and cats have a vagus nerve running from their brain stem. In both species, the nerve can be stimulated by defecation, leading to a pleasurable sensation and what some have labeled “poo-phoria,” or post-poop elation. In running, the cat may simply be working off excess energy brought on by stimulation of the nerve.

Less interesting is the notion that notoriously hygienic cats may simply want to shake off excess litter or fecal matter by running a 100-meter dash, or that a digestive problem has led to some discomfort they’re attempting to flee from. The fact is, so little research has been done in the field of pooping cat mania that there’s no universally accepted answer. Like so much of what makes cats tick, a definitive motivation will have to remain a mystery.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
Listen to the Impossibly Adorable Sounds of a Baby Sloth
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RODRIGO ARANGUA/AFP/GettyImages

Sometimes baby sloths seem almost too adorable to be real. But the little muppet-faced treasures don't just look cute—turns out they sound cute, too. We know what you're thinking: How could you have gone your whole life without knowing what these precious creatures sound like? Well, fear not: Just in time for International Sloth Day (today), we have some footage of how the tiny mammals express themselves—and it's a lot of squeaking. (Or maybe that's you squealing?)

The sloths featured in the heart-obliterating video below come from the Sloth Sanctuary of Costa Rica. The institution rescues orphaned sloths, rehabilitates them, and gets them ready to be released back into the wild.

[h/t The Kid Should See This]

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