Structurally colored fibers in nature

Two-dimensional fibrous photonic structures are frequent in nature. Such structures come in at least three different classes: fibre bundles, cylindrical multilayers and longitudinal patterning. We propose reviewing the occurrence of fibrous photonic structures in nature and develop the physical arguments that explain the optical properties of these light-reflecting fibers, isolated or grouped in more or less dense assemblies. We will also indicate how multiscale models appropriate for those kind of structures can be approached. With appropriate adaption of the size of the structure, the arguments are applicable in the visible, near-ultraviolet, infrared radiations, and in the thermal (far infrared) regime.