posted on 2018-05-21, 00:00authored byYuan Meng, Susan C. Fitzer, Peter Chung, Chaoyi Li, Vengatesen Thiyagarajan, Maggie Cusack
Shells
of oyster species belonging to the genus Crassostrea have similar shell microstructural features comprising well-ordered
calcite folia. However, the mechanical strengths of folia differ dramatically
between closely related species. For example, the calcareous shells
of the Hong Kong oyster Crassostrea hongkongensis are stronger than those of its closest relative, the Portuguese
oyster, Crassostrea angulata. Specifically, after
removal of organic content, the folia of C. hongkongensis are 200% tougher and able to withstand a 100% higher crushing force
than that of C. angulata. Detailed analyses of shell
structural and mechanical features support the hypothesis that crystallographic
interdigitations confer elevated mechanical strength in C.
hongkongensis oyster shells compared to C. angulata shells. Consequently, the folia of C. hongkongensis are structurally equipped to withstand a higher external load compared
to C. angulata. The observed relationships between
oyster shell structure, crystallography, and mechanical properties
provided an insightful context in which to consider the likely fate
of these two species in future climate change scenarios. Furthermore,
the interdisciplinary approach developed in this study through integrating
electron backscatter diffraction (EBSD) data into finite element analysis
(FEA) could be applied to other biomineral systems to investigate
the relationship between crystallography and mechanical behavior.