Scientists are constantly looking for new ways to enhance the effectiveness of body armour. One of the last places anyone would expect to find a lead is in the Brazilian Amazon River. Special fish that inhabit this river known as Arapaima gigas are equipped with skin that is able to repel the powerful bite of a piranha. This may be ideal as a basis for knife and ballistic protection.
Dr. Robert Ritchie, a scientist at University of California Berkeley, led the study on this topic. “What we are trying to do is create composite ceramics with the hard external layer and some flexible foundation to use as a shield or armor,” he reports.
The Arapaima gigas has skin (known as lamella) that has hardened overlapping layers. With this corrugated skin structure, the pressure of a predator’s bite is dispersed, similar to how state-of-the-art Kevlar works in a standard vest. The researchers have used X-ray to further examine the lamella of the Arapaima gigas. Upon the examination, they discovered that each layer of the fish is made of collagen (which makes up human hair and nails.) The outermost layers of the fish have high mineral content which makes it hard. The innermost layers have less content which makes it more flexible; an excellent combination.
It’s been discovered that the scales can resist 12 gigapascals of pressure, or 1.7 million pounds per square inch! Factory made diamonds are made using 18 gigapascals of pressure to illustrate an idea of how tough this is.
With one of the hardest bites for an animal its size, the piranha bite has been tested on the skin of the Arapaima gigas by researchers. It’s been reported that the teeth of the piranha cracked without fully penetrating the tough armoured skin of the Arapaima gigas. Further testing has to be done with this skin before it could be put into use.