The unique teeth of sea urchins allows them to eat through stone, but despite constant grinding, their teeth never get dull. Scientists from the University of Wisconsin-Madison and their colleagues have discovered the self-sharpening mechanism urchins use to maintain razor-sharp teeth, according to a recent study published in the journal Advanced Functional Materials. This discovery could lead to human tools that never need sharpening. Sea urchin teeth are biomineral mosaics comprised of plates and fibers of calcite crystals that are arranged crosswise and are cemented together with extremely hard calcite nanocement. Between these crystals, there are layers of organic materials that are not as sturdy as the calcite crystals. The tooth material will break at these predetermined weak spots. The scientists used techniques such as microscopy that utilized x-rays to illuminate how the nanocrystals are arranged. The unique arrangement allows the teeth to grind rock and constantly self-sharpen. Researchers say that discovering the secret of urchin teeth could have practical applications for human toolmakers. Incorporating the self-sharpening mechanism of sea urchin teeth could produce tools that sharpen themselves with use. The research was supported by grants from the US Department of Energy and the National Science Foundation. Researchers who contributed to this report were from the University of California, Berkeley; Argonne National Laboratory; the Weizmann Institute of Science; and the Lawrence Berkeley National Laboratory.
(Source: ScienceDaily, December 26, 2010)