Self-Sharpening Tools? Sea Urchins Show How
They eat through rocks and keep razor-sharp teeth
By John Johnson, Newser Staff
Posted Dec 31, 2010 3:02 PM CST
Shetland sea urchin   (Flickr)

(Newser) – The humble sea urchin may teach us how to make knives that never need to be sharpened. Scientists think they've figured out how the creature manages to eat through rock and still maintain teeth that never go dull, reports National Geographic. "It is one of the very few structures in nature that self-sharpen," says one researcher of each 2-centimeter tooth. Theoretically, scientists could mimic the composition—a complex arrangement of calcite crystals and weaker organic material—for humans tools. sums it up nicely: "The secret is how the teeth are constructed: layers of calcite biocrystals held together with calcite nanocement are interspersed with softer layers of organic material, and when the teeth start to get dull on the surface, the top organic layer flakes off, exposing a brand new and freshly sharp layer of calcite. Chew, flake, repeat, and you’ve got infinitely sharp teeth."

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Showing 3 of 4 comments
Jan 4, 2011 4:32 AM CST
Thanks for the interest in this work! If anyone would like to know more about the science behind this story, we've set the original paper free to access until the 4th of February; you can find it here: Adrian Miller Advanced Functional Materials
Dec 31, 2010 9:20 PM CST
My wife and I both got poked by the spines this past week in Maui. I was lucky to get only one. My wife had about a dozen -- both of us were stung around the knee. I was able to pull the tips of most of the spines out with tweezers, but a half dozen or so in my wife's leg remained. A cloth soaked in vinegar taped to her leg overnight dissolved the rest.
Dec 31, 2010 9:13 PM CST
That's no surprise to me. I have mermaids sharpen my tools all the time.