Parrotfish Teeth: Stiff Biominerals Whose Microstructure Makes Them Tough and Abrasion-Resistant to Bite Stony Corals

ORAL

Abstract

Parrotfish feed by biting stony corals. To investigate how their teeth endure such contact stress, we examine the composition, nano/micro- structure, and mechanical properties of the steephead parrotfish Chlorurus microrhinos tooth. Its enameloid is a fluorapatite biomineral with outstanding mechanical properties: the mean elastic modulus and hardness near the biting surface: 124 GPa and 7.3 GPa, resp., making it among the stiffest and hardest biominerals known; mean indentation yield strength is >6 GPa, and mean fracture toughness is 2.5 MPa.m1/2. This combination of properties yields high abrasion resistance. Fluorapatite shows X-ray linear dichroism at the Ca L-edge, enabling polarization-dependent contrast mapping1-2 of apatite, to quantitatively measure nanocrystal orientations. Parrotfish enameloid consists of 100-nm-wide, microns-long crystals, co-oriented and bundled into interwoven fibersm which decrease in average diameter from 5 µm at the back to 2 µm at the tooth tip. This size change is spatially correlated with an increase in hardness.3
1. PUPA Gilbert et al. PNAS 2011, 108, 11350
2. PUPA Gilbert et al. EPSL 2017, 460, 281
3. MA Marcus et al. ACS Nano 2017, DOI: 10.1021/acsnano.7b05044

*NSF grant DMR-1603192, DOE grant DE-FG02-07ER15899, DOE contract DE-AC02-05CH11231

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Presenters

  • Matthew Marcus

    • ALS/LBNL
    • Advanced Light Source, Lawrence Berkeley Laboratory

Authors

  • Matthew Marcus

    • ALS/LBNL
    • Advanced Light Source, Lawrence Berkeley Laboratory

  • Shahrouz Amini

    • Nanyang Technological University, Biological & Biomimetic Material Laboratory, School of Materials Science & Engineering

  • Cayla Stifler

    • Department of Physics, University of Wisconsin-Madison
    • Department of Physics, University of Wisconsin–Madison
    • Physics, Chemistry, Geoscience, Univ of Wisconsin

  • Chang-Yu Sun

    • Department of Physics, University of Wisconsin-Madison
    • Department of Physics, University of Wisconsin–Madison
    • Physics, Chemistry, Geoscience, Univ of Wisconsin
    • University of Wisconsin-Madison

  • Nobumichi Tamura

    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley Laboratory

  • Hans Bechtel

    • Advanced Light Source Division, Lawrence Berkeley National Lab
    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley Laboratory

  • Dilworth Parkinson

    • Advanced Light Source, Lawrence Berkeley Laboratory

  • Harold barnard

    • Advanced Light Source, Lawrence Berkeley Laboratory

  • Xiyue Zhang

    • Department of Physics, University of Wisconsin–Madison

  • Ali Miserez

    • Nanyang Technological University, Biological & Biomimetic Material Laboratory, School of Materials Science & Engineering

  • J. Q. Isaiah Chua

    • Nanyang Technological University, Biological & Biomimetic Material Laboratory, School of Materials Science & Engineering

  • Pupa Gilbert

    • Department of Physics, Chemistry, and Geoscience, University of Wisconsin-Madison
    • Department of Physics, University of Wisconsin-Madison
    • Department of Physics, University of Wisconsin–Madison
    • Physics, Chemistry, Geoscience, Univ of Wisconsin
    • Departments of Chemistry, Materials Science, and Geoscience, University of Wisconsin-Madison
    • University of Wisconsin-Madison
    • Univ of Wisconsin, Madison