To Be Seen or to Hide: Visual Characteristics of Body Patterns for Camouflage and Communication in the Australian Giant CuttlefishSepia apama

Abstract

Dryad data: http://dx.doi.org/10.5061/dryad.8527.abstract: 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 with 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 neighboring pixels. Sepia 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 with the backgrounds against which they are viewed. The measured image statistics of camouflaged animals closely resemble their backgrounds, while signaling animals differ significantly from their backgrounds. Our findings may provide the basis for a set of general rules for crypsis and signals. Furthermore, our methods may be widely applicable to the quantitative study of animal coloration.

Size Matters: Observed and Modeled Camouflage Response of European Cuttlefish (Sepia officinalis) to Different Substrate Patch Sizes during Movement

“…This is the first evidence for the existence of CEPS in moving cephalopods suggesting that a possible CEPS threshold laying somewhere between these values. It is worth noting that Chiao (Chiao and Hanlon, 2001) and Hanlon and Zylinski et al (Zylinski et al, 2011) alluded to a CEPS in stationary cuttlefish.…”

The Role of Life-History and Ecology in the Evolution of Color Patterns in Australian Chrysomeline Beetles

“…where for each sample (beetle or background), N is the length of the data vector,x is the mean of the data vector, and x i is element i of the data vector (Zylinski et al, 2011). This was calculated separately on the red, green and blue layers for each sample in MATLAB, using the Image Processing Toolbox.…”

“…Following Zylinski et al (2011), the spatial frequency of patterns within each sample (beetle and background) were analyzed using two-dimensional Fast Fourier Transformation (FFT). This was performed separately on the red, green and blue layers of each sample in MATLAB, using the Image Processing Toolbox.…”

Analyzing Visual Signals as Visual Scenes

“…Godfrey et al [1987] compared the Fourier transform of tiger and zebra stripes to that of their typical background to conclude that while both tigers and zebra were cryptic at low spatial frequencies, only tigers had patterning that was cryptic at high spatial frequencies. This technique has been applied to images of cuttlefish and eggshell patterns to assess their "granularity" objectively [Barbosa et al, 2008;Chiao et al, 2009;Spottiswoode and Stevens, 2012;Stoddard and Stevens, 2010;Zylinski et al, 2011]. This approach is very well suited to describing spotted or mottled patterns but begins to struggle at separating signal and noise when the signal contains more complex and irregular patterns elements.…”