May be a model of sea urchin teeth "a knife that can not be sharpened forever" may appear

Sea urchinCuts rocks with five sharp teeth and opens a hemispherical hole to hide, but the secret of that tooth that keeps sharpness without dullening even if you scrape hard rocks isUniversity of Wisconsin-MadisonIt was elucidated by the physicist of. Based on this discovery, it is theoretically possible to make a knife that keeps a sharp sharpness semipermanently, and it is expected that it can be used for tools etc in the future.

Details are as below.Ever-sharp urchin teeth may yield tool that never need honing (Dec. 22, 2010)

University of Wisconsin Madison School of PhysicsPupa GilbertProfessors and others, using various techniques using X-ray microscopyCalifornia purple sea urchin(California Murasaki Sea Urchin) to analyze the structure of the teeth, and elucidated its mechanism of maintaining sharpness without sharpening the teeth. Thesis isAdvanced Functional MaterialsIt is published in the magazine.

Tide PoolCalifornia murasaki sea urchin hiding in a round hole dug by himself.


There is a round hole when turned inside out. This is the mouth of the sea urchin.


There are five white calcareous teeth in the mouth.


Sea urchin teeth are always growing biominerals (minerals made by living organisms), two forms of plate and fibrousCalcite(Calcium carbonate) Are arranged so as to intersect each other, and it is structured to be adhered by nanocement of very hard calcite.

There is a layer of organic matter not as hard as calcite between crystal and crystal, and it seems to be missing in this fragile part when teeth are chipped. In other words, by strategically arranging "a place to come out" in advance, it is a mechanism that lacks the shape as desired, and it can be said that you are sharpening yourself every time you lack it. Professor Gilbert is comparing this mechanism to "paper with broken lines cut".

It seems that Professor Gilbert and others think that this discovery may be applicable to making tools for human beings. "It is theoretically possible to create blades that can be sharpened with use as well as the mechanisms of the sea urchin teeth kept sharp this time," Professor Gilbert says.