What they lack in size, they make up for in strength. Researchers at the University of Portsmouth in England say they may have found the world’s strongest material: snail teeth. The mighty limpet (Patella vulgata), a small aquatic snail housed in a conical shell, has some impressive chompers. The animal’s teeth, which are less than a millimeter in length, could be the strongest material on Earth, say scientists — ousting the previous record holder, spider silk.
Professor Asa Barber, who led the study, said of the findings, "Nature is a wonderful source of inspiration for structures that have excellent mechanical properties. All the things we observe around us, such as trees, the shells of sea creatures and the limpet teeth studied in this work, have evolved to be effective at what they do.
"Until now we thought that spider silk was the strongest biological material because of its super-strength and potential applications in everything from bulletproof vests to computer electronics but now we have discovered that limpet teeth exhibit a strength that is potentially higher."
It's tough down there
Limpets in the Gulf on Morbihan off the coast of France. (Photo: Auguste Le Roux/Wikimedia Commons)
The limpet can be found throughout the ocean, according to LiveScience, and is able to make a home even in harsh conditions such as deep canyons and turbulent surf. The hardy creature attaches to rocks with its foot, finding algae to eat as it scrapes over surfaces. The strong teeth leave scratch marks on the rocks as the creature moves, one of the characteristics that prompted researchers to look more closely at the teeth.
The secret to the strength of the limpet's teeth lies in the combination of chitin and a substance called goethite, a material that forms as the limpet grows. LiveScience reports that although goethite is hard, it’s not tough and can break. The chitin has stretchy fibers, so when it joins forces with the goethite, it creates something that is hard, strong and durable. Scientists tested the teeth using a method called atomic force microscopy, which pulls apart materials down to the level of the atom.
Barber explains, "Limpets need high strength teeth to rasp over rock surfaces and remove algae for feeding when the tide is in. We discovered that the fibres of goethite are just the right size to make up a resilient composite structure."
Barber talked to BBC about the difference between spider silk and limpet teeth: "People are always trying to find the next strongest thing, but spider silk has been the winner for quite a few years now. So we were quite happy that the limpet teeth exceeded that. One of my colleagues on the paper, from Italy, found some exotic spider silk that was about 4.5GPa, and we measured about 5GPa."
To put that in perspective, Barber compared the strength to a single string of spaghetti holding up 3,000 half-kilogram bags of sugar.
The team behind the study also noted that the strength of the material doesn’t alter or diminish when made larger.
"Generally a big structure has lots of flaws and can break more easily than a smaller structure, which has fewer flaws and is stronger," said Barber. "The problem is that most structures have to be fairly big so they’re weaker than we would like. Limpet teeth break this rule as their strength is the same no matter what the size."
The research team is thinking about practical applications for this new knowledge. "This discovery means that the fibrous structures found in limpet teeth could be mimicked and used in high-performance engineering applications such as Formula 1 racing cars, the hulls of boats and aircraft structures," said Barber, who is an engineer.
"Engineers are always interested in making these structures stronger to improve their performance or lighter so they use less material."
The findings were published in the Royal Society journal Interface.