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Roger T. Hanlon - One of the best experts on this subject based on the ideXlab platform.
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Rapid adaptive Camouflage in cephalopods
Oxford Research Encyclopedia of Neuroscience, 2019Co-Authors: Chuan-chin Chiao, Roger T. HanlonAbstract:Camouflage versatility is probably no better developed in the animal kingdom than in the coleoid cephalopods (octopus, squid, cuttlefish). These marine molluscs possess soft bodies, diverse behaviour, elaborate skin patterning capabilities and a sophisticated visual system that controls body patterning for communication and Camouflage (Packard 1995; Hanlon & Messenger 1996; Messenger 2001). Cephalopods form a key component of the food chain and are preyed upon by nearly all of the major carnivores in the ocean – an enormous variety of marine mammals, diving birds and teleost and elasmobranch fishes. Their primary defence is visual Camouflage (Hanlon & Messenger 1996). The diversity of visual systems represented by these predators is quite extraordinary and the Camouflaged body patterns of cephalopods have evolved in response to these selective pressures. Benthic shallow-water cephalopods have rapid adaptive Camouflage so that they can move about freely (foraging, finding mates, etc.) in multiple ecohabitats and avoid visual predation by tuning their Camouflage to nearly any visual background in their natural ranges.
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quantification of cuttlefish sepia officinalis Camouflage a study of color and luminance using in situ spectrometry
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2013Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Derya Akkaynak, Justine J Allen, Roger T. HanlonAbstract:Cephalopods are renowned for their ability to adaptively Camouflage on diverse backgrounds. Sepia officinalis Camouflage body patterns have been characterized spectrally in the laboratory but not in the field due to the challenges of dynamic natural light fields and the difficulty of using spectrophotometric instruments underwater. To assess cuttlefish color match in their natural habitats, we studied the spectral properties of S. officinalis and their backgrounds on the Aegean coast of Turkey using point-by-point in situ spectrometry. Fifteen spectrometry datasets were collected from seven cuttlefish; radiance spectra from animal body components and surrounding substrates were measured at depths shallower than 5 m. We quantified luminance and color contrast of cuttlefish components and background substrates in the eyes of hypothetical di- and trichromatic fish predators. Additionally, we converted radiance spectra to sRGB color space to simulate their in situ appearance to a human observer. Within the range of natural colors at our study site, cuttlefish closely matched the substrate spectra in a variety of body patterns. Theoretical calculations showed that this effect might be more pronounced at greater depths. We also showed that a non-biological method (“Spectral Angle Mapper”), commonly used for spectral shape similarity assessment in the field of remote sensing, shows moderate correlation to biological measures of color contrast. This performance is comparable to that of a traditional measure of spectral shape similarity, hue and chroma. This study is among the first to quantify color matching of Camouflaged cuttlefish in the wild.
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to be seen or to hide visual characteristics of body patterns for Camouflage and communication in the australian giant cuttlefish sepia apama
The American Naturalist, 2011Co-Authors: Roger T. Hanlon, Sarah Zylinski, Martin J How, Daniel Osorio, N J MarshallAbstract:It might seem obvious that a Camouflaged animal must generally match its background whereas to be conspicuous an organism must differ from the background. However, the image parameters (or statistics) that evaluate the conspicuousness of patterns and textures are seldom well defined, and animal coloration patterns are rarely compared quantitatively with their respective backgrounds. Here we examine this issue in the Australian giant cuttlefish Sepia apama. We confine our analysis to the best-known and simplest image statistic, the correlation in intensity between neighboring pixels. Sepia apama can rapidly change their body patterns from assumed conspicuous signaling to assumed Camouflage, thus providing an excellent and unique opportunity to investigate how such patterns differ in a single visual habitat. We describe the intensity variance and spatial frequency power spectra of these differing body patterns and compare these patterns with the backgrounds against which they are viewed. The measured image statistics of Camouflaged animals closely resemble their backgrounds, while signaling animals differ significantly from their backgrounds. Our findings may provide the basis for a set of general rules for crypsis and signals. Furthermore, our methods may be widely applicable to the quantitative study of animal coloration.
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a mimic octopus in the atlantic flatfish mimicry and Camouflage by macrotritopus defilippi
The Biological Bulletin, 2010Co-Authors: Roger T. Hanlon, Anya C. Watson, Alexandra BarbosaAbstract:The sand-dwelling octopus Macrotritopus de- filippi was filmed or photographed in five Caribbean loca- tions mimicking the swimming behavior (posture, style, speed, duration) and coloration of the common, sand-dwell- ing flounder Bothus lunatus. Each species was exceptionally well Camouflaged when stationary, and details of camou- flaging techniques are described for M. defilippi. Octopuses implemented flounder mimicry only during swimming, when their movement would give away Camouflage in this open sandy habitat. Thus, both Camouflage and fish mimicry were used by the octopuses as a primary defense against visual predators. This is the first documentation of flounder mimicry by an Atlantic octopus, and only the fourth con- vincing case of mimicry for cephalopods, a taxon renowned for its polyphenism that is implemented mainly by neurally controlled skin patterning, but also—as shown here— by their soft flexible bodies.
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cephalopod dynamic Camouflage bridging the continuum between background matching and disruptive coloration
Philosophical Transactions of the Royal Society B, 2009Co-Authors: Roger T. Hanlon, Chuan-chin Chiao, Alexandra Barbosa, Lydia M Mathger, Kendra C Buresch, Charles ChubbAbstract:Individual cuttlefish, octopus and squid have the versatile capability to use body patterns for background matching and disruptive coloration. We define—qualitatively and quantitatively—the chief characteristics of the three major body pattern types used for Camouflage by cephalopods: uniform and mottle patterns for background matching, and disruptive patterns that primarily enhance disruptiveness but aid background matching as well. There is great variation within each of the three body pattern types, but by defining their chief characteristics we lay the groundwork to test Camouflage concepts by correlating background statistics with those of the body pattern. We describe at least three ways in which background matching can be achieved in cephalopods. Disruptive patterns in cuttlefish possess all four of the basic components of ‘disruptiveness’, supporting Cott's hypotheses, and we provide field examples of disruptive coloration in which the body pattern contrast exceeds that of the immediate surrounds. Based upon laboratory testing as well as thousands of images of Camouflaged cephalopods in the field (a sample is provided on a web archive), we note that size, contrast and edges of background objects are key visual cues that guide cephalopod Camouflage patterning. Mottle and disruptive patterns are frequently mixed, suggesting that background matching and disruptive mechanisms are often used in the same pattern.
Lydia M Mathger - One of the best experts on this subject based on the ideXlab platform.
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quantification of cuttlefish sepia officinalis Camouflage a study of color and luminance using in situ spectrometry
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2013Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Derya Akkaynak, Justine J Allen, Roger T. HanlonAbstract:Cephalopods are renowned for their ability to adaptively Camouflage on diverse backgrounds. Sepia officinalis Camouflage body patterns have been characterized spectrally in the laboratory but not in the field due to the challenges of dynamic natural light fields and the difficulty of using spectrophotometric instruments underwater. To assess cuttlefish color match in their natural habitats, we studied the spectral properties of S. officinalis and their backgrounds on the Aegean coast of Turkey using point-by-point in situ spectrometry. Fifteen spectrometry datasets were collected from seven cuttlefish; radiance spectra from animal body components and surrounding substrates were measured at depths shallower than 5 m. We quantified luminance and color contrast of cuttlefish components and background substrates in the eyes of hypothetical di- and trichromatic fish predators. Additionally, we converted radiance spectra to sRGB color space to simulate their in situ appearance to a human observer. Within the range of natural colors at our study site, cuttlefish closely matched the substrate spectra in a variety of body patterns. Theoretical calculations showed that this effect might be more pronounced at greater depths. We also showed that a non-biological method (“Spectral Angle Mapper”), commonly used for spectral shape similarity assessment in the field of remote sensing, shows moderate correlation to biological measures of color contrast. This performance is comparable to that of a traditional measure of spectral shape similarity, hue and chroma. This study is among the first to quantify color matching of Camouflaged cuttlefish in the wild.
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cephalopod dynamic Camouflage bridging the continuum between background matching and disruptive coloration
Philosophical Transactions of the Royal Society B, 2009Co-Authors: Roger T. Hanlon, Chuan-chin Chiao, Alexandra Barbosa, Lydia M Mathger, Kendra C Buresch, Charles ChubbAbstract:Individual cuttlefish, octopus and squid have the versatile capability to use body patterns for background matching and disruptive coloration. We define—qualitatively and quantitatively—the chief characteristics of the three major body pattern types used for Camouflage by cephalopods: uniform and mottle patterns for background matching, and disruptive patterns that primarily enhance disruptiveness but aid background matching as well. There is great variation within each of the three body pattern types, but by defining their chief characteristics we lay the groundwork to test Camouflage concepts by correlating background statistics with those of the body pattern. We describe at least three ways in which background matching can be achieved in cephalopods. Disruptive patterns in cuttlefish possess all four of the basic components of ‘disruptiveness’, supporting Cott's hypotheses, and we provide field examples of disruptive coloration in which the body pattern contrast exceeds that of the immediate surrounds. Based upon laboratory testing as well as thousands of images of Camouflaged cephalopods in the field (a sample is provided on a web archive), we note that size, contrast and edges of background objects are key visual cues that guide cephalopod Camouflage patterning. Mottle and disruptive patterns are frequently mixed, suggesting that background matching and disruptive mechanisms are often used in the same pattern.
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disruptive coloration elicited on controlled natural substrates in cuttlefish sepia officinalis
The Journal of Experimental Biology, 2007Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Alexandra Barbosa, Kendra C Buresch, Sarrah Kaye, Roger T. HanlonAbstract:Cephalopods are known for their ability to change Camouflage body patterns in response to changes in the visual background. Recent research has used artificial substrates such as checkerboards to investigate some specific visual cues that elicit the various Camouflaged patterns in cuttlefish. In this study, we took information from experiments on artificial substrates and assembled a natural rock substrate (fixed with glue) with those features that are thought to elicit disruptive coloration in cuttlefish. The central hypothesis is that light rocks of appropriate size, substrate contrast and edge characteristics will elicit disruptive Camouflage patterns in cuttlefish. By adding graded light sand in successively greater quantities to this glued rock substrate, we predicted that disruptive Camouflage patterns would be replaced by progressively more uniform patterns as the visual features of rock size, contrast and edges were altered by the addition of sand. By grading the degree of disruptiveness in the animals' body patterns, we found that the results support this prediction, and that there is a strong correlation between fine details of the visual background properties and the resultant body pattern shown by the cuttlefish. Specifically, disruptive coloration was elicited (1) when one or a few light rocks of approximately the size of the animal's White square skin component were in the surrounding substrate (dark rocks alone did not elicit disruptive coloration), (2) there was moderate-to-high contrast between the light rocks and their immediate surrounds, and (3) the rock edges were well defined. Taken together, the present study provides direct evidence of several key visual features that evoke disruptive skin coloration on natural backgrounds.
Derya Akkaynak - One of the best experts on this subject based on the ideXlab platform.
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quantification of cuttlefish sepia officinalis Camouflage a study of color and luminance using in situ spectrometry
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2013Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Derya Akkaynak, Justine J Allen, Roger T. HanlonAbstract:Cephalopods are renowned for their ability to adaptively Camouflage on diverse backgrounds. Sepia officinalis Camouflage body patterns have been characterized spectrally in the laboratory but not in the field due to the challenges of dynamic natural light fields and the difficulty of using spectrophotometric instruments underwater. To assess cuttlefish color match in their natural habitats, we studied the spectral properties of S. officinalis and their backgrounds on the Aegean coast of Turkey using point-by-point in situ spectrometry. Fifteen spectrometry datasets were collected from seven cuttlefish; radiance spectra from animal body components and surrounding substrates were measured at depths shallower than 5 m. We quantified luminance and color contrast of cuttlefish components and background substrates in the eyes of hypothetical di- and trichromatic fish predators. Additionally, we converted radiance spectra to sRGB color space to simulate their in situ appearance to a human observer. Within the range of natural colors at our study site, cuttlefish closely matched the substrate spectra in a variety of body patterns. Theoretical calculations showed that this effect might be more pronounced at greater depths. We also showed that a non-biological method (“Spectral Angle Mapper”), commonly used for spectral shape similarity assessment in the field of remote sensing, shows moderate correlation to biological measures of color contrast. This performance is comparable to that of a traditional measure of spectral shape similarity, hue and chroma. This study is among the first to quantify color matching of Camouflaged cuttlefish in the wild.
Chuan-chin Chiao - One of the best experts on this subject based on the ideXlab platform.
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Rapid adaptive Camouflage in cephalopods
Oxford Research Encyclopedia of Neuroscience, 2019Co-Authors: Chuan-chin Chiao, Roger T. HanlonAbstract:Camouflage versatility is probably no better developed in the animal kingdom than in the coleoid cephalopods (octopus, squid, cuttlefish). These marine molluscs possess soft bodies, diverse behaviour, elaborate skin patterning capabilities and a sophisticated visual system that controls body patterning for communication and Camouflage (Packard 1995; Hanlon & Messenger 1996; Messenger 2001). Cephalopods form a key component of the food chain and are preyed upon by nearly all of the major carnivores in the ocean – an enormous variety of marine mammals, diving birds and teleost and elasmobranch fishes. Their primary defence is visual Camouflage (Hanlon & Messenger 1996). The diversity of visual systems represented by these predators is quite extraordinary and the Camouflaged body patterns of cephalopods have evolved in response to these selective pressures. Benthic shallow-water cephalopods have rapid adaptive Camouflage so that they can move about freely (foraging, finding mates, etc.) in multiple ecohabitats and avoid visual predation by tuning their Camouflage to nearly any visual background in their natural ranges.
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quantification of cuttlefish sepia officinalis Camouflage a study of color and luminance using in situ spectrometry
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2013Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Derya Akkaynak, Justine J Allen, Roger T. HanlonAbstract:Cephalopods are renowned for their ability to adaptively Camouflage on diverse backgrounds. Sepia officinalis Camouflage body patterns have been characterized spectrally in the laboratory but not in the field due to the challenges of dynamic natural light fields and the difficulty of using spectrophotometric instruments underwater. To assess cuttlefish color match in their natural habitats, we studied the spectral properties of S. officinalis and their backgrounds on the Aegean coast of Turkey using point-by-point in situ spectrometry. Fifteen spectrometry datasets were collected from seven cuttlefish; radiance spectra from animal body components and surrounding substrates were measured at depths shallower than 5 m. We quantified luminance and color contrast of cuttlefish components and background substrates in the eyes of hypothetical di- and trichromatic fish predators. Additionally, we converted radiance spectra to sRGB color space to simulate their in situ appearance to a human observer. Within the range of natural colors at our study site, cuttlefish closely matched the substrate spectra in a variety of body patterns. Theoretical calculations showed that this effect might be more pronounced at greater depths. We also showed that a non-biological method (“Spectral Angle Mapper”), commonly used for spectral shape similarity assessment in the field of remote sensing, shows moderate correlation to biological measures of color contrast. This performance is comparable to that of a traditional measure of spectral shape similarity, hue and chroma. This study is among the first to quantify color matching of Camouflaged cuttlefish in the wild.
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cephalopod dynamic Camouflage bridging the continuum between background matching and disruptive coloration
Philosophical Transactions of the Royal Society B, 2009Co-Authors: Roger T. Hanlon, Chuan-chin Chiao, Alexandra Barbosa, Lydia M Mathger, Kendra C Buresch, Charles ChubbAbstract:Individual cuttlefish, octopus and squid have the versatile capability to use body patterns for background matching and disruptive coloration. We define—qualitatively and quantitatively—the chief characteristics of the three major body pattern types used for Camouflage by cephalopods: uniform and mottle patterns for background matching, and disruptive patterns that primarily enhance disruptiveness but aid background matching as well. There is great variation within each of the three body pattern types, but by defining their chief characteristics we lay the groundwork to test Camouflage concepts by correlating background statistics with those of the body pattern. We describe at least three ways in which background matching can be achieved in cephalopods. Disruptive patterns in cuttlefish possess all four of the basic components of ‘disruptiveness’, supporting Cott's hypotheses, and we provide field examples of disruptive coloration in which the body pattern contrast exceeds that of the immediate surrounds. Based upon laboratory testing as well as thousands of images of Camouflaged cephalopods in the field (a sample is provided on a web archive), we note that size, contrast and edges of background objects are key visual cues that guide cephalopod Camouflage patterning. Mottle and disruptive patterns are frequently mixed, suggesting that background matching and disruptive mechanisms are often used in the same pattern.
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disruptive coloration elicited on controlled natural substrates in cuttlefish sepia officinalis
The Journal of Experimental Biology, 2007Co-Authors: Lydia M Mathger, Chuan-chin Chiao, Alexandra Barbosa, Kendra C Buresch, Sarrah Kaye, Roger T. HanlonAbstract:Cephalopods are known for their ability to change Camouflage body patterns in response to changes in the visual background. Recent research has used artificial substrates such as checkerboards to investigate some specific visual cues that elicit the various Camouflaged patterns in cuttlefish. In this study, we took information from experiments on artificial substrates and assembled a natural rock substrate (fixed with glue) with those features that are thought to elicit disruptive coloration in cuttlefish. The central hypothesis is that light rocks of appropriate size, substrate contrast and edge characteristics will elicit disruptive Camouflage patterns in cuttlefish. By adding graded light sand in successively greater quantities to this glued rock substrate, we predicted that disruptive Camouflage patterns would be replaced by progressively more uniform patterns as the visual features of rock size, contrast and edges were altered by the addition of sand. By grading the degree of disruptiveness in the animals' body patterns, we found that the results support this prediction, and that there is a strong correlation between fine details of the visual background properties and the resultant body pattern shown by the cuttlefish. Specifically, disruptive coloration was elicited (1) when one or a few light rocks of approximately the size of the animal's White square skin component were in the surrounding substrate (dark rocks alone did not elicit disruptive coloration), (2) there was moderate-to-high contrast between the light rocks and their immediate surrounds, and (3) the rock edges were well defined. Taken together, the present study provides direct evidence of several key visual features that evoke disruptive skin coloration on natural backgrounds.
Erik Learnedmiller - One of the best experts on this subject based on the ideXlab platform.
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it s moving a probabilistic model for causal motion segmentation in moving camera videos
European Conference on Computer Vision, 2016Co-Authors: Pia Bideau, Erik LearnedmillerAbstract:The human ability to detect and segment moving objects works in the presence of multiple objects, complex background geometry, motion of the observer, and even Camouflage. In addition to all of this, the ability to detect motion is nearly instantaneous. While there has been much recent progress in motion segmentation, it still appears we are far from human capabilities. In this work, we derive from first principles a likelihood function for assessing the probability of an optical flow vector given the 2D motion direction of an object. This likelihood uses a novel combination of the angle and magnitude of the optical flow to maximize the information about how objects are moving differently. Using this new likelihood and several innovations in initialization, we develop a motion segmentation algorithm that beats current state-of-the-art methods by a large margin. We compare to five state-of-the-art methods on two established benchmarks, and a third new data set of Camouflaged animals, which we introduce to push motion segmentation to the next level.