These animals inspire better body armor for humans
From piranha-proof fish to pangolins, meet the creatures that are literally tougher than nails.
If you’ve seen best-picture contender Black Panther leading up to this weekend’s Academy Awards, you probably marveled (gulp) at the title character’s vibranium suit. It’s pretty much the coolest armor ever made.
Except, perhaps, for some animals who make their own. Shells, exoskeletons, scales—it makes us wonder about these real-life super suits. Just how strong are they?
Meet the animals that scientists have turned to for body armor “bioinspiration.”
Armadillos
Despite reports of bullets ricocheting off armadillos, these creatures aren’t bulletproof. Their shells are made of bony plates called osteoderms that grow in the skin. They’re loosely connected for flexibility and are covered by a layer of keratin, the protein that makes up hair, nails, and horns, says Mariella Superina, chair of the IUCN’s anteater, sloth, and armadillo specialist group, via email.
“The shell protects the armadillos from thorny shrubs, under which they can hide from predators,” she says. But if a predator like a dog or raptor does get to them, they can still pretty easily break the shell. Think of their armor more like a hard-shelled suitcase than a bulletproof vest.
Nonetheless, the armadillo’s segmented osteoderms inspired researchers at Montreal’s McGill University to create a protective material out of glass plates segmented into hexagons and set atop a soft substrate. The material proved to be 70 percent more puncture-resistant than a continuous plate of the same thickness.
Abalone
This squishy gastropod lives in a shell that’s like a “bricks and mortar structure,” says Marc Meyers of the Jacobs School of Engineering at the University of California, San Diego. Meyers began studying animal as models for armor development 20 years ago for the U.S. Army.
The abalone makes numerous layers of calcium carbonate (chalk) plates, one-two hundredths the width a human hair and bound with a glue-like protein. Though chalk can brittle, abalone shells layer it like bricks, which makes it extra tough. And the protein—the "mortar"—allows the plates to slide so the shell can absorb impact without shattering.
Meyers and team hope that a better understanding of how the abalone shell’s structure works could help develop better bulletproof body armor for soldiers and police.
Arapaimas
“The arapaima is the piscine equivalent of the battleship,” Meyers says of these massive freshwater fish. They grow up to 10 feet long and can live in the close quarters with piranhas in the Amazon’s seasonal lakes, without fear of piranhas’ formidable chompers.
Arapaima armor consists of staggered layers of flexible scales made from layers of collagen and sealed in a mineralized cover, Meyers and his team found. They made their discovery by attaching piranha teeth to an industrial hole punch and bringing it down on arapaima scales embedded in rubber to mimic the fish’s muscle. The teeth can make it through one layer, but arapaimas have an average of three layers.
These tough yet flexible scales provide yet another inspiration to engineers looking to develop better armor. The tough outer layer prevents predators from biting through the scales, and the collagen has enough give to allow for significant impact before breaking. The scale’s corrugated surface helps it keep its integrity.
Ironclad Beetles
The ironclad beetle of the southwestern U.S. and Mexico is so tough that specimens can’t be pinned to boards. It takes a drill or hammer to get through these hard bodies. When threatened, some species yank their legs and antennae into special grooves in their shell, leaving frustrated predators outside their fortress of super tough solitude. (Learn about why insect populations are plummeting.)
Their thick exoskeletons are made of chitin, a polysaccharide, arranged such that one species, the diabolical ironclad beetle, can be run over by a car and still survive. Their compression-resistant exoskeletons also help prevent dehydration by providing the ability to collect, transport, and store water.
The tough exoskeleton and flexible legs of the ironclad beetle served as inspiration for defense contractor BAE Systems as it was developing suspension systems that would make military vehicles more able to withstand blast damage.
Pangolins
“Pangolins are covered with large, overlapping plates made entirely of keratin,” Superina says. In fact, they’re the only known mammal to have true scales and are affectionately known as “scaly anteaters.” The scales seem like they could be unwieldy—but not for these cuties from Asia and Africa.
Pangolin means “roller” in Malay for good reason. When a pangolin feels threatened, it rolls into a ball, using its scales as tough outer armor.
Their scales, made of keratin, are lightweight but surprisingly fracture-resistant thanks to the way the keratin is organized. And when the scales do crack, the cracks are directed away from the underlying soft tissue. Scientists at Northwestern who published a study on the structure of pangolin scales in 2017 say that this understanding could pave the way for body armor designed to deflect cracks.
“A lion cannot get a pangolin,” says Meyers. It leaves no place for a snack attack.
