Sea urchin’s teeth: Key to everlasting sharp tools

LONDON - Scientists have found how sea urchins keep their teeth sharp and believe that the same principle could help make knives which do not need sharpening.

The creatures have self-honing teeth which allow them to chomp through stone, carving out hideaways on rocky shores.

Scientists have learned how the urchins keep their teeth razor-sharp and believe that technology based on the same principle could create everlasting bladed tools, the Telegraph quoted the Advanced Functional Material journal as saying.

Analysing the teeth of the California purple sea urchin, the scientists found a complex structure of layered calcite crystals held together by super-hard natural cement.

Between the crystals are layers of weaker organic material. As each hard layer becomes blunt it breaks off, exposing a fresh crystalline surface beneath. In this way, the sea urchin’s teeth stay sharp.

Pupa Gilbert, who led the US team from the University of Wisconsin-Madison, said: “The organic layers are the weak links in the chain. There are breaking points at predetermined locations built into the teeth.

“It is a concept similar to perforated paper in the sense that the material breaks at these predetermined weak spots.”

The crystals come in two forms, plates and fibres, arranged crosswise in a tough “biomineral” mosaic.

Gilbert added: “Now that we know how it works, the knowledge could be used to develop methods to fabricate tools that could actually sharpen themselves with use.”