What gives a 3-meter-long Amazonian fish some of the toughest scales on Earth

Arapaima gigas is a big fish in a bigger river full of piranhas, but that doesn't mean it's an easy meal. It's evolved armor-like scales that deform, but don't tear or crack, when a piranha -- which has one of the animal kingdom's most powerful bites -- attacks. Researchers describe the unique properties of the Amazonian Arapaima skin and its potential for human-made materials.