Sea Urchin Teeth

The teeth of sea urchins are among the most complicated structures in the natural world. The image here shows the cross section of one tooth which looks a bit like a mushroom. In the higher magnification image, you can appreciate the details of imbricated minerals: the elongated structures are plates (the rounded ones are fibers) and these both are entirely made of calcite. The space between fibers and plates is completely filled by high-Mg calcite nanoparticles ten nanometers in size.

1. C. E. Killian, R. A. Metzler, Y. T. Gong, T. H. Churchill, I. C. Olson, V. Trubetskoy, M. B. Christensen, J. H. Fournelle, F. De Carlo, S. Cohen, J. Mahamid, A. Scholl, A. Young, A. Doran, F. H. Wilt, S. N. Coppersmith, and P.U.P.A. Gilbert.
   Self-sharpening mechanism of the sea urchin tooth.
   Adv. Funct. Mater. 21, 682-690 (2011). PDF
   • Royal Society of Chemistry, Urchins bare their teeth in materials research 01/07/11
   • National Geographic, Rock-Chewing Sea Urchins Have Self-Sharpening Teeth 12/28/10
   • NSF News 12/22/10
   • Ever-sharp urchin teeth may yield tools that never need honing 12/22/10
2. C. E. Killian, R. A. Metzler, Y. U. T. Gong, I. C. Olson, J. Aizenberg, Y. Politi, F. H. Wilt, A. Scholl, A. Young, A. Doran, M. Kunz, N. Tamura, S. N. Coppersmith, and P.U.P.A. Gilbert.
   Mechanism of calcite co-orientation in the sea urchin tooth.
   J. Am. Chem. Soc., 131, 18404-18409 (2009). PDF
3. Y. Ma, B. Aichmayer, O. Paris, P. Fratzl, A. Meibom, R. A. Metzler, Y. Politi, L. Addadi, P.U.P.A. Gilbert and S. Weiner.
   The grinding tip of the sea urchin tooth: exquisite control over calcite crystal orientation and Mg distribution.
   Procs. Natl. Acad. Sci. USA 106, 6048-6053 (2009). PDF SI New York Times article on this work
   • New York Times, Exquisitely Tipped Teeth Let Sea Urchin Carve a Home From Stone 10/30/09
4. L Yang, CE Killian, M Kunz, N Tamura, and PUPA Gilbert.
   Biomineral nanoparticles are space-filling.
   R. Soc. Chem. – Nanoscale 3, 603-609 (2011).PDF
5. CE Killian, PUPA Gilbert.
   Biomineral Single Crystals
   Science 339, 510-511
   Special Feature