Schulz-Mirbach, T.; Goetz, Andreas J.; Griesshaber, Erika; Plath, M.; Schmahl, Wolfgang W.
Texture and nano-scale internal microstructure of otoliths in the Atlantic molly, Poecilia mexicana: A high-resolution EBSD study.
In: Micron, Vol. 51: pp. 60-69
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Otoliths of modern bony fishes are massive polycrystalline structuresconsisting mainly of calcium carbonate (primarily aragonite), and 1-10\%organic residuals. Unlike other biomineralisates like shells, teeth andbones, they are not optimized for mechanical loads but serve the sensesof hearing and balance in the inner ear. We examined internal structuralvariation of otoliths through microstructural and texture analyses. Ourstudy applied the electron backscattered diffraction technique (EBSD) towhole sections of saccular otoliths on cave- and surface-dwelling fish.Application of high spatial resolution EBSD on otoliths of thelivebearing fish Poecilia mexicana allowed for an investigation ofcrystal orientation despite the small size (<150 nm) of aragonitecrystallites. Crystallites at the rims of otoliths had a higherstructural organization than those situated near the center, where nodominant orientation pattern was discernible. Moreover, the medial(sulcal) face of otoliths, which makes contact with the sensoryepithelium, was more structured than the lateral (antisulcal) face.