Camouflage in a dynamic world

We review how animals conceal themselves in the face of the need to move, and how this is modulated by the dynamic components and rapidly varying illumination of natural backgrounds. We do so in a framework of minimising the viewer’s signal-tonoise ratio. Motion can match that of the observer such that there is no relative motion cue, or mimic that of background objects (e.g. swaying leaves). For group-living animals, matched motion and coloration is a special case of the latter ‘motion masquerade’, where each animal is a potential signal against the noise of other individuals. Recent research shows that dynamic illumination, such as underwater caustics or dappled forest shade, greatly impedes detection of moving targets, so may change the balance of predator-prey interactions.