McCoy Dakota E, Feo Teresa, Harvey Todd Alan, Prum Richard O
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
Department of Vertebrate Zoology, MRC-116, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20013, USA.
Nat Commun. 2018 Jan 9;9(1):1. doi: 10.1038/s41467-017-02088-w.
Many studies have shown how pigments and internal nanostructures generate color in nature. External surface structures can also influence appearance, such as by causing multiple scattering of light (structural absorption) to produce a velvety, super black appearance. Here we show that feathers from five species of birds of paradise (Aves: Paradisaeidae) structurally absorb incident light to produce extremely low-reflectance, super black plumages. Directional reflectance of these feathers (0.05-0.31%) approaches that of man-made ultra-absorbent materials. SEM, nano-CT, and ray-tracing simulations show that super black feathers have titled arrays of highly modified barbules, which cause more multiple scattering, resulting in more structural absorption, than normal black feathers. Super black feathers have an extreme directional reflectance bias and appear darkest when viewed from the distal direction. We hypothesize that structurally absorbing, super black plumage evolved through sensory bias to enhance the perceived brilliance of adjacent color patches during courtship display.
许多研究已经表明色素和内部纳米结构如何在自然界中产生颜色。外部表面结构也会影响外观，例如通过引起光的多次散射（结构吸收）来产生天鹅绒般的超黑外观。在这里，我们展示了五种极乐鸟（雀形目：极乐鸟科）的羽毛通过结构吸收入射光，从而产生极低反射率的超黑羽毛。这些羽毛的定向反射率（0.05%-0.31%）接近人造超吸收材料的反射率。扫描电子显微镜、纳米计算机断层扫描和光线追踪模拟表明，超黑羽毛具有倾斜排列的高度改良的小羽枝，与正常黑色羽毛相比，这些小羽枝会引起更多的多次散射，从而导致更多的结构吸收。超黑羽毛具有极端的定向反射率偏差，从远端方向看时显得最黑。我们推测，结构吸收性的超黑羽毛是通过感官偏差进化而来的，以便在求偶展示过程中增强相邻色斑的视觉亮度。
