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 anti-predator tactic in natural selection. Many visual predators have keen color perception, 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 high-fidelity 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 tri-chromatic 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 3 of biological coloration, and (ii) provide supporting evidence that cuttlefish can produce color-coordinated camouflage on natural substrates despite lacking color vision.4

Artificial light pollution: are shifting spectral signatures changing the balance of species interactions?

“…However, ongoing advances in street lighting technology have led to the increasing adoption of broader spectrum light sources such as High Pressure Sodium (HPS), Light Emitting Diode (LED) and Metal Halide (MH) lamps (Elvidge et al ., ), which provide improved colour rendering capabilities for humans. Shifting and broadening the spectra of street lamps may lead to unforeseen environmental impacts because the spectral signature reflected from objects is an important cue that guides a number of animal behaviours, including, for example, the detection of resources (Chittka et al ., ; Hempel de Ibarra & Vorobyev, ; Macedonia et al ., ; Chiao et al ., ; Zou et al ., ), mate selection (Andersson et al ., ; Hunt et al ., ; Robertson & Monteiro, ; Lim et al ., ) and navigation (Cheng et al ., ; Möller, ; Mappes & Homberg, ; Reppert et al ., ; Ugolini et al ., ). Here, we ask whether the use of broad spectrum street lighting technologies is likely to improve the ability of animals to perform tasks during the night which are guided by the detection of light reflected from objects, and whether this could alter the balance of species interactions.…”

The adaptive value of camouflage and colour change in a polymorphic prawn

“…Other studies, such as the classic example of camouflage and industrial melanism in the peppered moth ( Biston betularia ) 6 , have used correlational evidence, often based on morph-specific recapture rates, or artifical prey targets 9 to support the hypothesis that better camouflaged individuals are less frequently attacked by predators. More recently, with a better understanding of the anatomy of predator eyes, spectral sensitivity and visual modelling, different studies have estimated how individuals are camouflaged based to the view of predators through the use of spectrometry 14 – 18 or digital imagery 19 , 20 . However, while all these studies comprise important evidence that individuals are efficiently concealed against the substrate, no study has directly quantified how closely differently coloured individuals match their background to predator eyes, and then how matching effectively reduces predation rates in natural conditions.…”

Reflective Light Modulation by Cephalopods and Fishes in Shallow Nearshore Habitats

“…After imaging cuttlefish in the summer of 2010 we spent this current year analyzing data. This paper was published in Proceedings of the National Academy of Sciences in February (Chiao et al, 2011) and was featured as a Research Highlight in Nature magazine as well. The basic question was: what does the camouflaged prey look like in the color space of the predator's visual system?…”