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  • You're probably pretty familiar with the Hollywood image of piranhas.

  • The water starts churning, and suddenly

  • an unlucky animal is nothing but a bare skeleton.

  • And yeah, piranhas can definitely do some damage,

  • but most of them aren't these ferocious monsters.

  • They eat lots of different things, and many piranhas

  • along with other tropical fishhave evolved

  • one pretty creative feeding strategy:

  • they steal scales off of other fish.

  • The act of eating another fish's scales is known as lepidophagy.

  • Part of the reason this is a thing at all is that scales

  • can actually be a pretty good food source

  • they're high in protein and important minerals,

  • and they're easy to come by.

  • If you're a fish, anyway.

  • No one even has to die in the process!

  • Fish can just do a drive-by and scrape off some scales to go.

  • That said, most scale-eating species don't only eat scales.

  • For the most part, they just go in for a nibble

  • when competition for resources gets stiff.

  • They eat scales to supplement their regular diet.

  • And they're not too discriminating.

  • If they need a bite to eat, they'll steal scales

  • off just about anyoneeven fish from their same species!

  • As for how they go about it, they have a few different methods.

  • Some fish use stealth to snag scales, or speed to grab 'n' go.

  • Some bite scales off cleanly, while others scrape or chew them loose.

  • No matter what the fish's method of choice is,

  • a special diet calls for special tools.

  • And some fish have adaptations precisely for eating scales.

  • For example, typical piranhas have wide jaws

  • that give them excellent leverage for deshingling the side of a passing fish.

  • And certain African cichlids are so ready for scale-snacking

  • that their mouths even grow at an angle.

  • These fish can be left- or right-mouthed, and they'll typically

  • come at a fish from their dominant side and use their mouths to twist off scales.

  • Meanwhile, the wimple piranha has opted for a morestraightforward tactic.

  • It approaches a fish from the side, then uses its blunt face

  • to basically T-bone its victim at full speed with its mouth open.

  • The collision knocks scales loose, and the piranha

  • then catches them as they sink.

  • Seems like overkill, but whatever works, I guess.

  • However they do it, these fish are able to get the nutrition

  • they need through a uniquely renewable resource.

  • Because the best part is, scales grow back!

  • It's probably a little unpleasant to get T-boned by a piranha,

  • but in general, the fish that get their scales stolen

  • or smashed off just bounce back fine.

  • Turns out, losing scales and regrowing them

  • is a natural part of fish life.

  • So as weird of a tactic as it is, lepidophagy

  • probably evolved as a strategy for when food sources are low.

  • Scales are plentiful, and this way, small predatory fish

  • that can't find enough smaller prey can always graze

  • on larger fish that are too big to take down.

  • It's a niche these fish can really thrive in,

  • and it makes them unique among even their closest relatives.

  • So while it may be a fish-eat-fish world most of the time,

  • some tropical predators have found a more peaceful way to coexist.

  • Thanks for watching this episode of SciShow!

  • And thank you to our patrons for making videos like this possible.

  • It takes a lot of people to make a SciShow video,

  • so your support goes a long way.

  • And if you're not a patron but you like what we do,

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  • [♪ OUTRO]

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