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Snails’ Teeth Beats Spider Silk As Nature’s Strongest Material

The discovery makes sense: Mollusks use these teeth to excavate rocks while they feed

(Brandon Tabiolo/Design Pics/Corbis)
smithsonian.com

Marine snails, commonly called limpets, cling tenaciously to rocks as waves batter them. They can clamp on with a force of 75 pounds per square inch, using their muscular mollusk "foot" and a chemical secretion. But even that feat isn’t as stunning as their ability to grind down rock as they feed, using a tooth-studded tongue called a radula. Now the snails have upped their tough-guy street cred with help from engineers based in the U.K., who discovered that these snails’ teeth are made of the strongest natural material out there.

Spider silk, often compared to kevlar, has wowed with its tough yet flexible powers. But when tested, the tooth material was, on average, about five times stronger than most spider silk, reports BBC News. This makes it the strongest natural material on Earth. Tests in the lab revealed that it can withstand pressure that would turn carbon into diamond. Thats’s comparable to a single strand of spaghetti holding up about 3,300 one-pound bags of sugar, the study’s lead author, Asa Barber of the University of Portsmouth, told the BBC. 

For Science, David Shultz reports:

Scientists discovered that the teeth are made of a mixture of goethite (an iron-containing crystal) nanofibers encased in a protein matrix. In spite of their amazing strength, the teeth don’t quite best the strongest humanmade materials like graphene, but the new material’s upper range puts it far ahead of Kevlar and on par with the highest quality carbon fibers.

The researchers published their findings in the Journal of the Royal Society Interface

If you're looking for the strongest overall material on Earth, diamond is a good guess, but again, man-made nano-materials beat it. And there are also two rare, natural materials that can withstand more stress than diamond, reports New Scientist

One of those—wurtzite boron nitrate—has a diamond-like arrangement at the atomic level. But while diamonds are made only of carbon, wurtzite boron nitrate also contains (as its name suggests) boron and nitrogen. The other—lonsdaleite—is all carbon but has a hexagonal structure. (Diamond’s cubic.) Lonsdaleite can be created when graphite-containing meteorites plummet to Earth, and it can withstand 58 percent more stress than diamond.

Hard and strong-yet-flexible materials offer attractive properties for engineers looking to build the next generation of materials, structures and even machines. Now they’ll be turning to the snails as the latest potential nature consultants on these projects.

Editor’s Note April 5, 2017: As pointed out by one of our eagle-eyed readers Tom Tonon, the terminology in this story could cause confusion for some readers. There are many different scientific terms used to describe an object’s capacity to resist bending or breaking apart, each of which has subtle differences. In this article, we use the terms toughness and strength to refer to the object’s tensile strength—the capacity of an object to resist pulling apart. This differs from compressive strength, which describes the amount of squeezing an object could withstand. The above discussion of wurtzite boron nitrate refers to not to tensile strength but the hardness of the material, which is its capacity to resist scratching or cutting.

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