Measurement System for

An important question in marine ecology is how appearance is influenced by environment. In the open ocean, the development of a wide variety of predator visual systems has resulted in a great diversity of adaptive coloration for prey camouflage. In particular, there are photonic structures in the skin of marine animals that specifically evolved for hiding in the complex radiance of pelagic waters. In order to understand the principles under which these structures operate, a detailed characterization of their optical properties is required. One useful property that can be measured is the bidirectional reflectance distribution function (BRDF) and its dependence on angle. To satisfy this goal, an optical instrument was designed and constructed to measure the BRDF of various types of animal skin. After testing, the instrument was taken to the Sea of Cortez, where it was used to measure partial hemisphere reflectance functions for multiple marine species, including squid. The instrument performed well over its available angular range to provide useful reflectance information that can be used to compare animals within and between species. The results reveal interesting angular reflectance behavior and point the way toward future studies and improvements in methodology. BACKGROUN