Limpet teeth dislodges spider silk as strongest natural material


Spider silk

Spider silk

This is, indeed, a very interesting discovery.

So interesting that Spiderman may, in time, want to change his identity and may no longer be shooting silk webs from his wrists to swing between buildings, catch bad guys, stop a wayward train, or even save motorists cars from falling off bridges.

But then if he does that, he may opt not to be called Spiderman anymore, but ‘Limpetman’. How’s that?

If anything, Spiderman, the movie, tries not only to portray himself as a hero, but also characterizes the usefulness and strength of the magical spider silk.

It is said that spider silk is as elastic as nylon, six times lighter than steel of the same strength, five times stronger than steel (on a weight-to-strength basis), and able to withstand temperatures of 300 degrees Celsius.

Scientists are still trying to unlock this last part of the spider silk puzzle and replicate the process that nature has provided.

Limpet snails

Limpet snails

However, while the spider silk phenomenon continues to be studied and replicated, researchers from the University of Portsmouth have discovered that limpets – small aquatic snail-like creatures with conical shells – have teeth with biological structures stronger than that of the spider silk.

“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,” Asa Barber, who led the study, said.

Professor Barber found that the teeth contain a hard mineral known as goethite, which forms in the limpet as it grows.

He said: “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.

“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.

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

A scanning electron microscope image of limpet teeth.

A scanning electron microscope image of limpet teeth.

The teeth were also found to be of the same strength no matter what size – Barber and his team tested samples that were about a 100 times thinner than the diameter of a human hair.

According to him, this is important because the more compact a material is, the less flaws and weak points it has, making the structure harder and more reliable.

“The strength of limpet teeth is, on average, 4.9 GPa – that is like trying to break a piece of spaghetti with 3,000 bags of sugar. The second strongest material is spider silk at up to about 4 GPa, followed by bamboo at almost 1 GPa,” explained Barber. (Note: GPa is a strength unit of measure.)

In terms of man-made materials, limpet teeth are stronger than Kevlar and almost as good as the best high-performance carbon materials.

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