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MIT researchers are investigating how a primitive fish uses its scaly exoskeleton to protect itself from the sharp teeth of its predators. The scientists' goal is to develop a better kind of armor for soldiers to similarly protect them from bullets, shrapnel, and bombs.

The 16-inch-long Polypterus senegalus - which is commonly called the gray bichir or "dinosaur eel" although it's not technically an eel - has been around for at least 96 million years. Like many fish of that era, the dinosaur eel is cloaked in light-weight full-body armor. Few modern fish possess such a protective suit, making the old fish a living relic of dinosaur times.

The researchers studied how the dinosaur eel protects itself while swimming in its native habitat of muddy, freshwater pools in West Africa. The dinosaur eel's scales are a mere 10^-8 meters thick, but the MIT team discovered how the layers of the scales combine to protect the fish's soft body.

The scientists found that the four layers of scales are made of different materials, with specific geometries, thicknesses, and inter-layer junctions that contribute to the extremely efficient design that helps it survive attacks and bites.

In their study, the scientists mimicked a biting attack on a piece of scale that had been surgically removed from a living fish. When bitten, the scales could dissipate the energy of the strike. By forcing the crack to make a circle around the site of penetration, the scales kept the damage localized, rather than spreading throughout the entire armor, which is what happens in many ceramic materials.

The researchers hope that some of these design characteristics could be used in the development of armor for soldiers, military vehicles, and other protective gear.

The study appears in a recent issue of Nature Materials.

via: MIT