#NATURE MOTION BACKGROUND SKIN#
The generation of 2D skin patterns relies on a motor system that controls the expansion state of up to several million pigment cells (chromatophores) embedded in the animal’s skin 5, among other specialized cell types 17, 20. These sophisticated operations are carried out instinctively 18 by the brain of animals that diverged from us more than 550 million years ago 19, well before large brains existed. Pattern matching does not consist of a faithful reproduction of the substrate’s appearance but, rather, of the visually initiated statistical estimation and generation of that appearance 5. We studied here the 2D features of camouflage and therefore refer to them as skin patterns and to the process as pattern matching. Although both components are technically textural 4, 15, 16, in this field the term ‘texture’ is often applied only to 3D features, caused, for example, by the contraction of skin papillae 5, 17. Pattern motion during blanching was direct and fast, consistent with open-loop motion in low-dimensional pattern space, in contrast to that observed during camouflage.Ĭephalopod camouflage consists of matching the animal’s appearance to that of its substrate and typically contains two-dimensional (2D) and three-dimensional (3D) components. Finally, we compared camouflage to blanching, a skin-lightening reaction to threatening stimuli. Components could also be differentiated by their sensitivity to spatial frequency. However, their identities varied even across transitions between identical skin-pattern pairs, indicating flexibility of implementation and absence of stereotypy. These components varied in shapes and sizes, and overlay one another. Chromatophores could be grouped into pattern components on the basis of their covariation during camouflaging. An analysis of hundreds of thousands of images over natural and artificial backgrounds revealed that the space of skin patterns is high-dimensional and that pattern matching is not stereotyped-each search meanders through skin-pattern space, decelerating and accelerating repeatedly before stabilizing. Here, using quantitative methods 14, we studied camouflage in the cuttlefish Sepia officinalis as behavioural motion towards background matching in skin-pattern space. Behavioural experiments also indicated that, although camouflage requires vision, its execution does not require feedback 5, 12, 13, suggesting that motion within skin-pattern space is stereotyped and lacks the possibility of correction.
Analysis of cuttlefish images proposed that camouflage patterns are low dimensional and categorizable into three pattern classes, built from a small repertoire of components 8, 9, 10, 11. This behaviour relies on a visual assessment of the surroundings, on an interpretation of visual-texture statistics 2, 3, 4 and on matching these statistics using millions of skin chromatophores that are controlled by motoneurons located in the brain 5, 6, 7. This indicates that this time the air alarm should not be ignored.Many cephalopods escape detection using camouflage 1. She runs to the basement and meows loudly. My neighbour’s cat, Melania, senses when a rocket flies in the direction of our city. A friend is forced to leave her pet in the apartment and run to the storage room alone. My friend’s dog hides far under the bed every time he hears the sound of a siren. People are forced to enter bomb shelters.
Air raid alarms are often heard in Ukraine. But the thought of sudden danger and urgent evacuation holds us back. It was difficult for people to find shelter, feed themselves and their children. She was amazed by the huge number of animals that Ukrainians brought to the Warsaw railway station and the temporary animal shelter. My friend Tatiana emigrated to Poland in the first days of the war. Most hotels and hostels did not allow pets. When I left Ukraine with my children and friends in March 2022, there were four dogs in my car - three Spitz and one Maltese.
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