Scientists study fish scales in hopes of creating penetration-resistant materials

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One day, scientists hope to make lightweight, synthetically derived armor and other flexible, penetration-resistant materials — today, they are studying the scales of fish to determine how this can be done.

Lawrence Berkeley National Laboratory researcher and UC Berkeley professor Robert Ritchie worked with UC San Diego professor Marc Meyers and a team of four other scientists on the study published June 5. They found the mechanism that makes the fish scales of carp both flexible and strong, which allows fish to wriggle and swim in the manner they do while still protecting themselves from predators such as other fish. Their research was funded by the U.S. Air Force.

“Nature designs things very differently,” Ritchie said. “It generates remarkable properties.”

The scientists previously studied the compositions of sea shells, hair, teeth, bones and arapaimas, which are the largest freshwater fish in the Amazon.

According to Ritchie, they chose to study the carp because it is considered a modern fish and could be compared to more stiff ancient fish that were previously thought to be extinct, such as the coelacanth found off the coast of Africa.

“Scales have to be protective but also allow the fish to be flexible,” Ritchie said.

Fish scales, which are made of collagen, are especially intriguing because of their gradient structure, according to Ritchie.

While the top layer of fish scales is tough — which allows the animals to have a layer of protection in dangerous waters, such as those of the piranha-infested Amazon River — the subsequent layers gradually become more ductile. This prevents a fish’s exterior from cracking or severely limiting motion.

“We can’t bite into a brick, for example,” Ritchie said, discussing how the fish’s hard exterior protects it from predators. “But, if the whole fish scale is made of a hard material, it might shatter.”

According to Ritchie, inside the carp scales, there are structures that resemble spiral staircases — little bundles of collagen arranged in a spiral pattern — that allow the metaphorical stair steps to move and not break when the scale is stressed with pressure.

The main goal of the research is to eventually develop synthetic materials that can be used for a myriad purposes, such as lightweight, flexible armor.

In addition to the obstacle of understanding how the natural structures work to imitate them, the scientists also have the constraint of current human innovation, and Ritchie said developing a new material could take decades.

Ritchie said the ability to produce materials as complex as nature’s is not yet completely developed. He added that 3D printing, which might eventually be an option, is still in its rudimentary stages and cannot be trusted for quality.

In the short term, Ritchie said although the team’s program with the Air Force has ended, researchers have begun studying pine cones, catfish, pelicans’ pouches and other organisms for their structures. He added that the scientists have other papers that have not yet been published.

Kate Finman is the executive news editor. Contact her at [email protected] and follow her on Twitter at @KateFinman_DC.