Image copyright NOAA. Photographer: Claire Fackler, CINMS, NOAA

New research shows how sea urchins are able to keep their teeth always sharp despite gnawing away at rock and other hard surfaces in their never-ending search for food. The new discovery could help researchers and inventors create self-honing knives that always have a sharp edge.By studying the teeth of the California purple sea urchin, scientists discovered the unique properties that allow them to eat their way through stone to create shelters in the rocky coast. The team found a complex layer of calcite crystals held together with a natural super hard cement. Between these crystals are layers of weaker organic material allowing that allow the blunt edges to break away as the edge of the urchins’ teeth become dull.

“The organic layers are the weak links in the chain. There are breaking points at predetermined locations built into the teeth,” said Professor Pupa Gilbert, who led the US team from the University of Wisconsin-Madison. “”It is a concept similar to perforated paper in the sense that the material breaks at these predetermined weak spots.”

Analysis has shown he crystals come in two forms, plates and fibers, arranged crosswise in a tough biomineral mosaic allowing the teeth to remain sharp. The latest report appears in the journal Advanced Functional Material and Gilbert adds, “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.”

[via Telegraph UK]