Does the crystal structure of shark teeth make them stronger?

C. megalodon, a huge ancient shark, was capable of producing bite forces as large as 110,000-180,000 N¹. In comparison, great white sharks, a much smaller modern analogue, can only exert a force of 7,400 N when biting¹. In both cases, the mechanical stress that the teeth undergo suggests that there might be mesoscale structural features in the fluorapatite crystals in enameloid, which contribute to the superior mechanical properties. Previously, we used PIC (Polarization-dependent Imaging Contrast)^2,3 mapping to reveal an intricate woven structure in the fluorapatite crystals in parrotfish enameloid, and hypothesized that this structure contributes to enameloid’s impressive stiffness⁴. PIC maps from megalodon and great white shark reveal the mesoscale c-axis orientations of enameloid crystals, which contribute to understanding the structure that allows shark teeth to withstand the large bite forces.

1 S Wroe 2008 DOI: 10.1111/j.1469-7998.2008.00494.x
2 PUPA Gilbert 2011 DOI: 10.1073/pnas.1107917108
3 CE Killian 2011 DOI: 10.1002/adfm.201001546
4 M Marcus 2017 DOI: 10.1021/acsnano.7b05044