Clinging like a limpet

We’ve known for a long time that limpets are extremely good at hanging onto rocks and other surfaces, but engineers have shown that the phrase “clinging like a limpet” couldn’t be more appropriate. The team from the University of Portsmouth found that a limpet’s teeth are made from the strongest biological material ever tested; they’re even stronger than spider silk.

These limpet teeth look fearsome but they're actually only 1mm long.
These limpet teeth look fearsome but they’re actually only 1mm long.

The incredible strength of limpet teeth seems to be due to the thinness of the mineral-protein composite (called goethite)  that the teeth are made from, and the way these goethite fibres are tightly-packed together. The University of Portsmouth team, led by Professor Asa Barber, found that the strength of the teeth is about five gigaPascals, the same as the pressure needed to turn carbon into diamond and ten times stronger than human teeth. Or as Professor Barber explained, it’s equivalent to a single strand of spaghetti supporting 3,000 half-kilo bags of sugar.

But why do limpets need such strong teeth? It’s partly because of their need to remain attached to rocky, often smooth surfaces, but it’s also because of their diet.  A limpet’s teeth are attached to its tongue and help it to scrape algae from the rock they’re attached to; often the limpet will end up eating tiny rock particles as well. This causes its poo to harden to a concrete-like substance. Ouch.

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