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Knife-wielding crabs? Here’s the troubling truth behind these viral videos.

Just take a look at this video in which a crab wielding a knife seemingly fends off an attacker or a would-be cook.

Perhaps it's the crab's surly-looking demeanor or the way it wildly waves the knife as it shuffles away that made this footage go viral. A similar video caught fire online last month.

Are we in the midst of a crustacean uprising? Nah.

Don't take my word for it. I talked to guy who would know: Jack Cover, general curator for the National Aquarium in Baltimore. "It's a hoax," he said of the video above.

It appears the knife's handle is jammed into the claw, and the crab either can't let got of it or is instinctively clamping down on the weapon.

"It's a normal behavior. If the knife wasn't there, the crab would be swinging around," Cover said. "You can put a plastic gun in that crab's claw as well and it'd look like a gun-wielding crab."

The crab is "absolutely distressed," he added.

That's less surprising in the world of viral animal videos than we'd like to think: While it's pretty obvious that, say, passing around a dolphin for selfies until it dies is not so great, lots of sneakier animal harassment manages to pass for adorable shenanigans. Videos and photos of animals being put in hilarious situations or "playing" with humans may actually show animals in distress.

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The crab in the video above is probably a Cardisoma guanhumi, commonly referred to as a blue land crab (although they come in all sorts of colors). These creatures can be found in throughout Central America, the Carribean and parts of South America.

These large land crabs can grow to the size of grapefruits, Cover said, and it's not unusual to see them crossing streets in the coastal areas where they live. "Sometimes hundreds of those crabs get smashed on the road" when they're migrating for reproduction, he added.

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"Purely from a biologist's standpoint, I'm surprised the video is getting the attention it's getting. To me, it's sort of showing a little bit about our tendency to be very separate from nature," Cover said. "A crab is not known for its large brain and it's already  got a pretty formidable weapon -- that claw."

Yeah, forget that knife! This crab's massive claw is its last line of defense against predators.

"If that thing clamped down on your finger, you'd get a pretty heavy-duty blood blister," Cover said. "It's not going to sever a finger, but there's a lot of muscle in that claw."


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