The Air Force is funding research into piranha-proof Amazon fish scales for future body armor

Military Tech

VIDEO: How the Army is working to make body armor stronger and lighter

WASHINGTON (Reuters) - One of the world's largest freshwater fish is protected by the natural equivalent of a "bulletproof vest," helping it thrive in the dangerous waters of the Amazon River basin with flexible armor-like scales able to withstand ferocious piranha attacks.

Researchers from the University of California, San Diego and University of California, Berkeley on Wednesday described the unique structure and impressive properties of the dermal armor of the fish, called Arapaima gigas. They said their findings can help guide development of better body armor for people as well as applications in aerospace design.


(Reuters/Denis Balibouse)

Diver Alex Reeson checks on the Arapaima or Pirarucu fishes in the tropical section of Europe's biggest freshwater aquarium Aquatis, due to open October 21, in Lausanne, Switzerland October 17, 2017.

The fish, also known as pirarucu, gets up to 10 feet (3 meters) long and weighs up to 440 pounds (200 kg). Arapaima, a fish that can breathe air and survive up to a day outside of the water, inhabits rivers in Brazil, Guyana and Peru infested with piranhas, known for razor-sharp teeth, incredible bite strength and deadly feeding frenzies.

There long has been an evolutionary arms race in which predators develop ways to kill - like sharp teeth - and other animals develop ways to stay alive like the dermal armor seen in various fish, dinosaurs and mammals over time. Arapaima's scales, the researchers said, possess all the best attributes of a bulletproof vest, but the elements are better integrated into one solid piece combining imperviousness and flexibility.

"Such lightweight and tough materials like fish scales are the sexy topics that materials scientists are pursuing," said Wen Yang, a UCSD materials scientist who helped lead the study published in the journal Matter.

"It is true that the natural armor is similar to artificial body armor because of the similar scale overlapping system. However, the natural armor such as these fish scales is tough and much lighter, without impeding body flexibility and locomotion," Yang added. "Remember that the fish scales were developed through hundreds of millions of years. They are very advanced."

The researchers conducted laboratory tests of the scales.

The scales, they found, have a hard mineralized outer layer to resist penetration that is bound to a tough-but-flexible inner layer by collagen – the main structural protein in skin and other connective tissues in the body.

This structure means the scales can become deformed when bitten by a piranha but are not torn, broken or pierced, protecting the fish from injury.

"We were able to see how the collagen fibers deform without a catastrophic failure including the mechanisms of twisting, folding, sliding, stretching, delamination," Yang said.

The study was backed by the U.S. Air Force Office of Scientific Research.


A C-17 Globemaster III assigned to the 911th Airlift Wing is towed across the flightline at March Air Reserve Base, California, Jan. 7, 2020. (Air Force photo by Joshua J. Seybert)

March Air Reserve Base in California will host nearly 200 U.S. citizens who were flown out of Wuhan, China due to the rapidly-spreading coronavirus, a Defense Department spokeswoman announced on Wednesday.

"March Air Reserve Base and the Department of Defense (DoD) stand ready to provide housing support to Health and Human Services (HHS) as they work to handle the arrival of nearly 200 people, including Department of State employees, dependents and U.S. citizens evacuated from Wuhan, China," said Pentagon press secretary Alyssa Farah in a statement on Wednesday.

Wuhan is the epicenter of the coronavirus, which is a mild to severe respiratory illness that's associated with symptoms of fever, cough and shortness of breath, according to the Centers for Disease Control and Prevention.

The virus has so far killed 132 people and infected nearly 6,000 others in China, according to news reports.

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