How Nanopores and Microcavities Control the Light Reflectance Properties of Snake Ventral Scales

All natural organisms have adapted themselves for survival over millions of years of evolution. For example, snakes have developed nanofeatures on their ventral scales in specific geometry and orientation to ease their locomotion. In addition to that, some snakes have also optimized their scales to control their thermoregulatory and optical properties. Some snakes living in hot and humid equatorial climates have developed reflective white ventral scales to avoid overheating caused by highly radiative soil and rocks. Our analysis shows that nanopores embedded inside these ventral scales scatter light to achieve reflective white surfaces. Interestingly, they are also highly reflective in the near-infrared regime of the electromagnetic spectrum, which might help them to avoid overheating. In comparison with these reflective scales, amorphous structures, rather than nanopores, have been found in transparent/translucent scales. These transparent/translucent scales showed greatly reduced reflective qualities in visible and near-infrared light. Some snakes have developed silvery-white ventral scales. Instead of nanopores, alternating layers of microcavities are found in the scales of these species. Our experimental results suggest that these layers interact with visible light to develop silvery-white surfaces utilizing a “chirped mirror” mechanism. In my presentation, I will discuss several examples of how snakes optimize their optical properties.