Zhao Shulei, Brady Parrish Clawson, Gao Meng, Etheredge Robert Ian, Kattawar George W, Cummings Molly E
Department of Integrative Biology, University of Texas, Austin, TX 78712, USA
Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
J R Soc Interface. 2015 Mar 6;12(104):20141390. doi: 10.1098/rsif.2014.1390.
Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields.
在开阔海洋中躲避捕食者很困难，因为没有物体可以藏身其后。鱼类的银色体表在开阔水域的伪装中起着重要作用。已经提出了各种模型来解释鱼皮的宽带反射，这些模型涉及鸟嘌呤晶体反射器排列的一维变化，然而这些鸟嘌呤片层的三维结构尚未得到很好的表征。在这里，我们报告了一种银色海鱼——大眼鲳（Selene vomer）体表鸟嘌呤片层的三维结构和光学特性。我们的结构分析和计算模型表明，鱼皮中具有随机偏航角的鸟嘌呤片层堆叠通过颜色混合产生宽带反射。鸟嘌呤片层和胶原层的光轴紧密排列，并提供了影响皮肤偏振反射的体双折射特性。这些数据表明了大眼鲳如何在不同的入射偏振角下保持或改变偏振状态。这些由鸟嘌呤片层和胶原层的结构所产生的光学特性可能对在变化光场中的开阔海洋伪装具有重要意义。
