Hyperspectral imaging of cuttlefish camouflage indicates good color match in the eyes of fish predators

Abstract

Camouflage is a widespread phenomenon throughout nature and an important antipredator tactic in natural selection. Many visual predators have keen color perception, and thus camouflage patterns should provide some degree of color matching in addition to other visual factors such as pattern, contrast, and texture. Quantifying camouflage effectiveness in the eyes of the predator is a challenge from the perspectives of both biology and optical imaging technology. Here we take advantage of hyperspectral imaging (HSI), which records full-spectrum light data, to simultaneously visualize color match and pattern match in the spectral and the spatial domains, respectively. Cuttlefish can dynamically camouflage themselves on any natural substrate and, despite their colorblindness, produce body patterns that appear to have highfidelity color matches to the substrate when viewed directly by humans or with RGB images. Live camouflaged cuttlefish on natural backgrounds were imaged using HSI, and subsequent spectral analysis revealed that most reflectance spectra of individual cuttlefish and substrates were similar, rendering the color match possible. Modeling color vision of potential di-and trichromatic fish predators of cuttlefish corroborated the spectral match analysis and demonstrated that camouflaged cuttlefish show good color match as well as pattern match in the eyes of fish predators. These findings (i) indicate the strong potential of HSI technology to enhance studies of biological coloration and (ii) provide supporting evidence that cuttlefish can produce color-coordinated camouflage on natural substrates despite lacking color vision.Sepia officinalis | skin coloration | defense | predator-prey | visual perception

Escape Distance in Ground-Nesting Birds Differs with Individual Level of Camouflage

“…Camouflage is a classic example of evolution through natural selection, and the selective advantage of cryptic phenotypes in avoiding predation has received considerable attention in recent years (Vignieri et al 2010;Chiao et al 2011;Zylinski and Johnsen 2011;Troscianko et al 2013). A widespread camouflage strategy is background matching, whereby an animal closely resembles its surroundings in color, brightness, and pattern (Stevens and Merilaita 2009a).…”

Camouflage and Perceptual Organization in the Animal Kingdom

“…a praying mantis in foliage, concealed both to its insect prey and reptilian and avian predators), the common denominators will prevail over viewer-specific solutions. As the ultimate common denominator is the physical world one might, for example, expect the colours of many camouflaged animals to be based on pigments that have similar reflectances to natural backgrounds across a broad spectral range, even though in principle a metamer might be effective against any one visual system (Wente & Phillips 2005;Chiao et al 2011).…”

Spectral discrimination in color blind animals via chromatic aberration and pupil shape

“…Neither of these explanations resolves the puzzle of "color-blind camouflage," and researchers remain in search of a mechanism that allows for this ability (7,(14)(15)(16). We are unaware of a proposal for how natural selection would drive the evolution and maintenance of colorful intraspecific displays in these soft-bodied mollusks if this information was not available to the animals themselves.…”

“…Despite this chromatically active behavior, genetic and physiological studies (4-7) show that (with one exception) cephalopods lack multiple photoreceptor types. Cephalopods also fail certain behavioral trials (7-11) designed to test for color vision by opponent spectral channels.We are faced with two distinct but related paradoxes: (i) how can these animals with a single photoreceptor achieve good background color matching, and (ii) why would they break camouflage to produce risky colorful mating displays (readily visible to predators with color vision) unless this chromatic information was visible to conspecifics and carried some selective advantage?Previous attempts to reconcile these apparent paradoxes include suggestions that (i) the animals do not actually match natural background colors (12) or (ii) multiple photoreceptor types could exist (13,14) in the animal's skin. Neither of these explanations resolves the puzzle of "color-blind camouflage," and researchers remain in search of a mechanism that allows for this ability (7,(14)(15)(16).…”

“…Previous attempts to reconcile these apparent paradoxes include suggestions that (i) the animals do not actually match natural background colors (12) or (ii) multiple photoreceptor types could exist (13,14) in the animal's skin. Neither of these explanations resolves the puzzle of "color-blind camouflage," and researchers remain in search of a mechanism that allows for this ability (7,(14)(15)(16).…”