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

Abstract

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 108 (2011):9148-9153, doi:10.1073/pnas.1019090108.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.We gratefully acknowledge financial support from the National Science Council of Taiwan NSC-98-2628-B-007-001-MY3 to CCC, from the Network Science Center at West Point and the Army Research Office to JKW, from the NDSEG Fellowship to JJA, and from ONR grant N000140610202 to RTH