An exciting new biological discovery was published yesterday (18 February 2015) based on research by scientists, Asa H. Barber , Dun Lu and Nicola M. Pugno. They have revealed the natural biological material that ranks the highest on record for tensile strength is none other than…..Limpet Teeth!
Okay, so be honest. Did you know that limpets had teeth? I must admit that I did not. My experience of limpets is limited to marvelling at the way that their little conical shells clung to rock faces, forevermore, being pounded by the sea. They seemed impossible to remove. As I child I wondered what they did in there and how they ate, but I had mostly put those questions aside…until now! This is an opportunity to learn more about limpets and these lessons could even teach our greatest engineers a thing or two.
Beneath the pointy shell, limpets have a strong muscular foot, which attaches to the rough surface of the rock. They also emit a sticky mucous, like a glue which seals them tight in their chosen position. This barrier keeps moisture locked inside and prevents them from being washed away by the sea. It also stops meddling…should I say, curious kids from prying them off!
They feed using a long tongue, known as a radula. This consists of a long chitinous ribbon, covered with tiny sharp teeth. The teeth scrape against the rock, removing algae..delicious!
Prof Steven Hawkins, of the University of Southampton described Limpets as “….the bulldozers of the seashore. The reason limpet teeth are so hard is that when they’re feeding, they actually excavate rock. In fact, if you look at their faecal pellets they actually look like little concrete blocks – because by the time it’s gone through their gut it’s hardened.”
Atomic Force Microscopy
A limpet’s tooth is around 1mm long and is made up of a mix of protein and fine tightly packed mineral non fibres – called goethite. The teeth were ground down and the tensile strength was measured using new technology – atomic force microscopy. Barber, Lu and Pugnon were able to analyse a minute sample of a limpet’s tooth, down to it’s atomic level. Each sample was 100 times thinner than a human hair!
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