http://www.bbc.co.uk/news/science-environment-31500883

The strongest biological material known before today has been spider silk (typically measured at ~1 gigapascals (GPa), although there is an exotic spider silk that has been measured at about 4.5GPa). A recent study (lead author: Professor Asa Barber, University of Portsmouth, and published in Interface, a journal of the Royal Society) has discovered that limpet teeth are even stronger than the strongest spider silk, and stronger than Kevlar.

Limpet teeth are tiny (<1mm), and are made of a mineral+protein composite. The limpets use their teeth to scrape food from the rocks to which they cling:

Prof Steven Hawkins, of the University of Southampton, and who studies limpets, says:

... limpet teeth are so hard 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.

It seems that the secret to the teeth’s strength is in the thinness of their tightly packed mineral fibres. Those fibres, consisting of an iron-based mineral called goethite, are laced through a protein base in much the same way as carbon fibres can be used to strengthen plastic. Prof Barber & his team used an atomic force microscope to measure the strength of the tooth material which was, on average, about five GPa, which is five times greater than most spider silk, and sets a new record for biology, even when considering the most unusual spiders. That is:-

• about the same as the pressure needed to turn carbon into diamond beneath the Earth’s crust
• can be compared to a single string of spaghetti holding up 3,000 half-kilogram bags of sugar

(damn strong!)

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Alex Kemp