A piranha or piraña, native to the freshwater bodies of South America is largely known for their ferocious predatory behavior. Armed with a dangerous bite – actually one of the most forceful bites measured in vertebrates relative to their body mass – the piranhas are feared by even humans and they are portrayed in a very deadly light in the popular culture for their feeding frenzy. But even in the most intense piranha infested waters of South America, a big, meaty fish called Arapaima gigas co-exists successfully, with an impressive defense system against the deadly teeth of piranhas. Arapaima gigas, one of the four species of the genus Arapaima, is native to the basin of the Amazon River. They have a streamlined body and often grow to a length of up to 10 feet and can weigh about 200 kg, which make them one of the world’s largest freshwater fishes. Also known as pirarucu, they are commonly found in Brazil, Peru and Guyana. They are air-breathers and can extract oxygen from the surface air, which allow the pirarucu to survive in oxygen-low waters.

The Piranha-Proof Fish!

So what is the secret behind Arapaimas survival among piranhas? The secret is a unique natural body armor, one of the most wonderful evolutions of natural world. The Arapaimas have an armor like dermal layer, which helps them thwart any attempts of attacks from the piranhas. They are protected by a set of highly impermeable yet flexible multi-layered scales, evolved over millions of years, which help them deflect the sharp teeth of predators. The inner layer of this scale is soft and spongy and is made up of sheets of collagen – the main structural protein that holds the body together – and is capable of twisting and compressing when pressure is exerted. The hard outer layer is also made up of collagen, but it is mineralized with calcium making it extremely tough and capable of preventing penetration when bitten. These layers are arranged in a manner, which ingeniously absorbs stress while under attack, without causing injuries. Research studies are being conducted by defense companies on the Arapaimas, which is believed to help science in developing highly resilient bulletproof vests and body armor for humans.