Uncovering the structural and compositional properties of the chitin-based photonic array framework of the Sapphirinia metallina copepod

The remarkable colors of many animals are produced by the interaction of light with periodic arrays of guanine crystals. These arrays are formed by specialized cells in which remarkable control over crystal morphology and assembly is obtained using strategies that are beyond the state of the art in materials science. How animals template and regulate the formation of these structures remained largely unknown. Here we propose to study the guanine crystals and the chitin-based frameworks of the Sapphirinia metallina copepod, a small planktonic crustacean, to uncover the strategies used by these animals to produce a remarkably ordered array of crystals. We will do so by scanning SAXS/ XRF of copepods cross-sections, to map the structure and composition of the intracellular chitin-frameworks. Additionally, we will WAXS to follow the orientation of the guanine crystals, to determine the structural variations which facilitate the change in the crystal periodicities during color change.