Biological Sciences, National University of Singapore, 117543 Singapore.
Engineering Product Development, Singapore University of Technology and Design, 487372 Singapore.
J R Soc Interface. 2023 May;20(202):20230135. doi: 10.1098/rsif.2023.0135. Epub 2023 May 31.
Optical transparency is rare in terrestrial organisms, and often originates through loss of pigmentation and reduction in scattering. The coloured wings of some butterflies and moths have repeatedly evolved transparency, offering examples of how they function optically and biologically. Because pigments are primarily localized in the scales that cover a colourless wing membrane, transparency has often evolved through the complete loss of scales or radical modification of their shape. Whereas bristle-like scales have been well documented in glasswing butterflies, other scale modifications resulting in transparency remain understudied. The butterfly achieves transparency while retaining its scales and exhibiting blue/cyan transparent zones. Here, we investigate the mechanism of wing transparency in by light microscopy, focused ion beam milling, microspectrophotometry and optical modelling. We show that transparency is achieved via loss of pigments and vertical orientation in normal paddle-like scales. These alterations are combined with an anti-reflective nipple array on portions of the wing membrane being more exposed to light. The blueish coloration of the transparent regions is due to the properties of the wing membrane, and local scale nanostructures. We show that scale retention in the transparent patches might be explained by these perpendicular scales having hydrophobic properties.
在陆生生物中，光学透明度较为罕见，通常源于色素沉着的丧失和散射的减少。一些蝴蝶和飞蛾的彩色翅膀反复进化出透明性，为它们的光学和生物学功能提供了范例。由于色素主要存在于覆盖无色翅膀膜的鳞片中，因此透明度通常通过鳞片的完全缺失或其形状的根本改变而进化而来。虽然玻璃翼蝴蝶中的刷状鳞片已被充分记录，但其他导致透明度的鳞片改变仍未得到充分研究。这种蝴蝶在保留其鳞片的同时实现了透明度，并表现出蓝色/青色透明区域。在这里，我们通过光学显微镜、聚焦离子束铣削、微分光光度计和光学建模来研究 的翅膀透明度的机制。我们表明，透明度是通过色素的丧失和正常桨状鳞片的垂直取向来实现的。这些变化与翅膀膜上更多暴露在光线下的部分的抗反射乳头阵列相结合。透明区域的蓝色调是由于翅膀膜和局部鳞片纳米结构的特性所致。我们表明，透明斑块中鳞片的保留可以解释为这些垂直鳞片具有疏水性。
