To be seen or to hide: visual characteristics of body patterns for camouflage and communication in the Australian giant cuttlefish, Sepia apama.

It might seem obvious that a camouflaged animal must generally match its background whereas to be conspicuous an organism must differ from the background. However, the image parameters (or statistics) that evaluate the conspicuousness of patterns and textures are seldom well-defined, and animal coloration patterns are rarely compared quantitatively to their respective backgrounds. Here we examine this issue in the Australian giant cuttlefish Sepia apama. We confine our analysis to the best-known and simplest image statistic, the correlation in intensity between neighbouring pixels. S. apama can rapidly change their body patterns from assumed conspicuous signaling to assumed camouflage, thus providing an excellent and unique opportunity to investigate how such patterns differ in a single visual habitat. We describe the intensity variance and spatial frequency power spectra of these differing body patterns, and compare these patterns to the backgrounds against which they are viewed. The m...