How camouflage works

Merilaita, Sami; Scott‐Samuel, Nicholas E.; Cuthill, Innes C.

doi:10.1098/rstb.2016.0341

Cited by 191 publications

(205 citation statements)

References 92 publications

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“…background complexity decreases the signal-to-noise ratio that predators must process in order to detect prey (Endler, 1992;Merilaita, Scott-Samuel, & Cuthill, 2017). Correspondingly, crabs were easiest to find from more homogeneous mudflat background followed by polychromatic mussel beds and hardest to find in more heterogeneous rock pools.…”

Section: Discussionmentioning

confidence: 99%

Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs

et al. 2019

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Animals from many taxa, from snakes and crabs to caterpillars and lobsters, change appearance with age, but the reasons why this occurs are rarely tested. We show the importance that ontogenetic changes in coloration have on the camouflage of the green shore crabs ( Carcinus maenas ), known for their remarkable phenotypic variation and plasticity in colour and pattern. In controlled conditions, we reared juvenile crabs of two shades, pale or dark, on two background types simulating different habitats for 10 weeks. In contrast to expectations for reversible colour change, crabs did not tune their background match to specific microhabitats, but instead, and regardless of treatment, all developed a uniform dark green phenotype. This parallels changes in shore crab appearance with age observed in the field. Next, we undertook a citizen science experiment at the Natural History Museum London, where human subjects (“predators”) searched for crabs representing natural colour variation from different habitats, simulating predator vision. In concert, crabs were not hardest to find against their original habitat, but instead, the dark green phenotype was hardest to detect against all backgrounds. The evolution of camouflage can be better understood by acknowledging that the optimal phenotype to hide from predators may change over the life history of many animals, including the utilization of a generalist camouflage strategy. A plain language summary is available for this article.

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Section: Discussionmentioning

confidence: 99%

Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs

et al. 2019

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“…So too with camouflage, as the bulk of the theory and examples relate to coloration; but non‐visual camouflage follows the same principles (Ruxton, ). Two principles are essential to understanding camouflage: (1) whichever mechanism is employed, it acts to reduce the signal‐to‐noise ratio (Merilaita, Scott‐Samuel & Cuthill, ), and (2) both signal and noise are filtered in species‐specific ways (Endler, , ; Endler et al ., ).…”

Section: Exploiting Receiver Psychologymentioning

confidence: 99%

“…Studies of the physical properties of the signal and noise (in the case of coloration, the distribution of the reflected light in wavelength, time and space) are also tangential to understanding how camouflage works; what matters is psychophysics, not physics. This is because there is a massive reduction in the quantity of data between the physical signal and its encoding by a brain, and it is these perceptual ‘shortcuts’ that camouflage can exploit (Troscianko et al ., ; Merilaita et al ., ). There are three principle bottlenecks: in the eye, at the optic nerve and, finally, through attention.…”

Section: Exploiting Receiver Psychologymentioning

confidence: 99%

“…The 'signal' is the object of interest and the 'noise' is anything else, so the conceptual framework is one of accurate classification. Whether a prey to be consumed or a predator to be avoided, the same principle of discrimination between relevant and non-relevant stimuli can be applied at any stage in information-processing (Merilaita et al, 2017). Reduction in signal-to-noise ratio relates to the pattern of stimulation of neurones in a visual system, not the pattern of light, because signal and noise are filtered in species-specific ways.…”

Section: Exploiting Receiver Psychologymentioning

confidence: 99%

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Camouflage

2019

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Animal camouflage has long been used to illustrate the power of natural selection, and provides an excellent testbed for investigating the trade‐offs affecting the adaptive value of colour. However, the contemporary study of camouflage extends beyond evolutionary biology, co‐opting knowledge, theory and methods from sensory biology, perceptual and cognitive psychology, computational neuroscience and engineering. This is because camouflage is an adaptation to the perception and cognition of the species (one or more) from which concealment is sought. I review the different ways in which camouflage manipulates and deceives perceptual and cognitive mechanisms, identifying how, and where in the sequence of signal processing, strategies such as transparency, background matching, disruptive coloration, distraction marks, countershading and masquerade have their effects. As such, understanding how camouflage evolves and functions not only requires an understanding of animal sensation and cognition, it sheds light on perception in other species.

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“…Animals have evolved a bewildering diversity of color patterns. Some of these color patterns are used to signal to the opposite sex (e.g., Baldwin & Johnsen, ; Engelking, Roemer, & Beisenherz, ; Lim, Land, & Li, ), but perhaps the majority help in providing protection from potential predators (e.g., see reviews by Stevens and Merilaita (), Merilaita, Scott‐Samuel, and Cuthill () and Cuthill ()). The visual camouflage strategies employed by animals to escape detection by predators are diverse, and it can be challenging to identify how these signals serve their protective function.…”

Section: Introductionmentioning

confidence: 99%

What's in a band? The function of the color and banding pattern of the Banded Swallowtail

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Wilts

Tan

et al. 2020

Ecology and Evolution

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Butterflies have evolved a diversity of color patterns, but the ecological functions for most of these patterns are still poorly understood. The Banded Swallowtail butterfly, Papilio demolion demolion, is a mostly black butterfly with a greenish‐blue band that traverses the wings. The function of this wing pattern remains unknown. Here, we examined the morphology of black and green‐blue colored scales, and how the color and banding pattern affects predation risk in the wild. The protective benefits of the transversal band and of its green‐blue color were tested via the use of paper model replicas of the Banded Swallowtail with variations in band shape and band color in a full factorial design. A variant model where the continuous transversal green‐blue band was shifted and made discontinuous tested the protective benefit of the transversal band, while grayscale variants of the wildtype and distorted band models assessed the protective benefit of the green‐blue color. Paper models of the variants and the wildtype were placed simultaneously in the field with live baits. Wildtype models were the least preyed upon compared with all other variants, while gray models with distorted bands suffered the greatest predation. The color and the continuous band of the Banded Swallowtail hence confer antipredator qualities. We propose that the shape of the band hinders detection of the butterfly's true shape through coincident disruptive coloration; while the green color of the band prevents detection of the butterfly from its background via differential blending. Differential blending is aided by the green‐blue color being due to pigments rather than via structural coloration. Both green and black scales have identical structures, and the scales follow the Bauplan of pigmented scales documented in other Papilio butterflies.

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How camouflage works

Cited by 191 publications

References 92 publications

Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs

Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs

Camouflage

What's in a band? The function of the color and banding pattern of the Banded Swallowtail

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