Data from: A nanostructural basis for gloss of avian eggshells

The role of pigments in generating the colour and maculation of birds' eggs is well characterized, whereas the effects of the eggshell's nanostructure on the visual appearance of eggs are little studied. Here, we examined the nanostructural basis of glossiness of tinamou eggs. Tinamou eggs are well known for their glossy appearance, but the underlying mechanism responsible for this optical effect is unclear. Using experimental manipulations in conjunction with angle-resolved spectrophotometry, scanning electron microscopy, atomic force microscopy and chemical analyses, we show that the glossy appearance of tinamou eggshells is produced by an extremely smooth cuticle, composed of calcium carbonate, calcium phosphate and, potentially, organic compounds such as proteins and pigments. Optical calculations corroborate surface smoothness as the main factor producing gloss. Furthermore, we reveal the presence of weak iridescence on eggs of the great tinamou (Tinamus major), an optical effect never previously documented for bird eggs. These data highlight the need for further exploration into the nanostructural mechanisms for the production of colour and other optical effects of avian eggshells.

色素在鸟类蛋壳色彩与斑纹形成中的作用已得到充分阐释，然而蛋壳纳米结构对蛋壳视觉外观的影响却鲜有研究。本研究针对䳍鸟蛋壳的光泽性纳米结构基础展开探究。䳍鸟蛋壳以其光泽外观广为人知，但该光学效应背后的潜在机制仍不明晰。本研究结合实验操控与角分辨分光光度法、扫描电子显微镜、原子力显微镜及化学分析手段，证实䳍鸟蛋壳的光泽外观源自一层极为光滑的角质层，该角质层由碳酸钙、磷酸钙，以及可能存在的蛋白质、色素等有机化合物构成。光学计算结果证实，表面光滑度是产生光泽的核心影响因素。此外，本研究还发现大䳍（Tinamus major）的蛋壳存在微弱虹彩现象，这是此前从未在鸟类蛋壳中被记录过的光学效应。上述研究结果凸显了进一步探究鸟类蛋壳色彩及其他光学效应产生的纳米结构机制的必要性。