Made by nature - limpet teeth are made of a material stronger than a spider web

Limpet teeth could teach engineers a lesson

Limpet teeth are made of what is possibly the strongest known natural material, scientists have found, saying engineers should take inspiration from the simple creatures.

Using atomic force microscopy to understand the mechanical behaviour of the teeth of the small aquatic snails, researchers from the University of Portsmouth discovered the material it was made of was even stronger than spider web, so far considered the greatest material marvel of the natural world.

“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,” said Professor Asa Barber from the University’s School of Engineering who led the study.

“Until now we thought that spider silk was the strongest biological material because of its super-strength and potential applications in everything from bullet-proof vests to computer electronics, but now we have discovered that limpet teeth exhibit a strength that is potentially higher.”

The researchers suggested the mechanical properties and elaborate design of limpet teeth could be replicated by engineers developing materials and structures which require extreme resilience, such as racing cars and aeroplanes.

“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,” Professor Barber commented.

“Engineers are always interested in making these structures stronger to improve their performance or lighter so they use less material.”

The researchers found the extraordinary properties of limpet teeth are partly due to the fact the minuscule organ contains an extremely hard mineral known as goethite, which is produced in the animal’s body as it grows.

Surprisingly, the analysis revealed that unlike most other structure, limpet teeth are the same strength regardless of their size.

“Generally a big structure has lots of flaws and can break more easily than a smaller structure, which has fewer flaws and is stronger,” explained Professor 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.”

Being slightly less than a millimetre long and curved, the organ presented the researchers with many challenges

“The testing methods were important as we needed to break the limpet tooth,” Barber said. “It is curved, so the strength is dependent on both the shape of the tooth and the material. We wanted to understand the material strength only so we had to cut out a smaller volume of material out of the curved tooth structure.”

The team ended up with a sample almost 100 times thinner than a human hair. Analysing such tiny objects is only possible thanks to methods which have only recently been developed.

Limpets, the conic shaped creatures plentiful on rocks around the UK coast, use their powerful teeth to hold to rock surfaces during tides and to forage on algae. Their impressive strength has been known to biologists as it is frequently impossible to remove the creatures without injuring or even killing them.

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