There are very few fish that, in the rivers of South America, are able to withstand the attack of a pack of piranhas. Their sharp teeth penetrate the sturdier armor and cut even the toughest meat. Unless you are an arapaima (Arapaima gigas) a fish that reaches 2 meters and that according to some is a true "living fossil": it must breathe air to survive and is equipped with a bone skull, similar to that of fossil species of the Miocene.

(Fossils living in the depths of the abyss: look)

Armored scales
In addition to these characteristics, it has been discovered that its scales are able to withstand the bite of piranhas because they have a very particular structure. Under a very resistant outer layer there is in fact another flexible layer, which absorbs the "blow" of the predatory fish without breaking. According to the researchers it is possible to take inspiration from the structure of the arapaima scales to design more robust armor and protections.

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