scholarly journals Cephalopod dynamic camouflage: bridging the continuum between background matching and disruptive coloration

2008 ◽  
Vol 364 (1516) ◽  
pp. 429-437 ◽  
Author(s):  
R.T Hanlon ◽  
C.-C Chiao ◽  
L.M Mäthger ◽  
A Barbosa ◽  
K.C Buresch ◽  
...  
Keyword(s):  
Visual Cues ◽  
The Body ◽  
Background Matching ◽  
Disruptive Coloration ◽  
Size Contrast ◽  
Body Patterns ◽  
Three Body ◽  
Web Archive ◽  
Body Pattern ◽  
The Continuum

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.

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

scholarly journals Cuttlefish dynamic camouflage: responses to substrate choice and integration of multiple visual cues

2009 ◽  
Vol 277 (1684) ◽  
pp. 1031-1039 ◽  
Author(s):  
Justine J. Allen ◽  
Lydia M. Mäthger ◽  
Alexandra Barbosa ◽  
Kendra C. Buresch ◽  
Emilia Sogin ◽  
...  
Keyword(s):  
Visual Cues ◽  
Substrate Preference ◽  
Artificial Substrates ◽  
Energy Costs ◽  
Evolutionary Response ◽  
Substrate Choice ◽  
Left And Right ◽  
Body Patterns ◽  
Insight Into ◽  
Body Pattern

Prey camouflage is an evolutionary response to predation pressure. Cephalopods have extensive camouflage capabilities and studying them can offer insight into effective camouflage design. Here, we examine whether cuttlefish, Sepia officinalis , show substrate or camouflage pattern preferences. In the first two experiments, cuttlefish were presented with a choice between different artificial substrates or between different natural substrates. First, the ability of cuttlefish to show substrate preference on artificial and natural substrates was established. Next, cuttlefish were offered substrates known to evoke three main camouflage body pattern types these animals show: Uniform or Mottle (function by background matching); or Disruptive. In a third experiment, cuttlefish were presented with conflicting visual cues on their left and right sides to assess their camouflage response. Given a choice between substrates they might encounter in nature, we found no strong substrate preference except when cuttlefish could bury themselves. Additionally, cuttlefish responded to conflicting visual cues with mixed body patterns in both the substrate preference and split substrate experiments. These results suggest that differences in energy costs for different camouflage body patterns may be minor and that pattern mixing and symmetry may play important roles in camouflage.

An ethogram of the Humboldt squid Dosidicus gigas Orbigny (1835) as observed from remotely operated vehicles

Behaviour ◽  
2015 ◽  
Vol 152 (14) ◽  
pp. 1911-1932 ◽  
Author(s):  
Lloyd A. Trueblood ◽  
Sarah Zylinski ◽  
Bruce H. Robison ◽  
Brad A. Seibel
Keyword(s):  
Open Ocean ◽  
The Body ◽  
Dosidicus Gigas ◽  
Remotely Operated Vehicles ◽  
Functional Roles ◽  
Video Recordings ◽  
Humboldt Squid ◽  
Body Patterns ◽  
Body Pattern

Many cephalopods can rapidly change their external appearance to produce multiple body patterns. Body patterns are composed of various components, which can include colouration, bioluminescence, skin texture, posture, and locomotion. Shallow water benthic cephalopods are renowned for their diverse and complex body pattern repertoires, which have been attributed to the complexity of their habitat. Comparatively little is known about the body pattern repertoires of open ocean cephalopods. Here we create an ethogram of body patterns for the pelagic squid, Dosidicus gigas. We used video recordings of squid made in situ via remotely operated vehicles (ROV) to identify body pattern components and to determine the occurrence and duration of these components. We identified 29 chromatic, 15 postural and 6 locomotory components for D. gigas, a repertoire rivalling nearshore cephalopods for diversity. We discuss the possible functional roles of the recorded body patterns in the behavioural ecology of this open ocean species.

scholarly journals A Report on Introduced Amazon Sailfin Catfish, Pterygoplichthys pardalis in Gombak Basin, Selangor, with Notes on Two Body Patterns of the Species

2020 ◽  
Vol 43 (4) ◽  
Author(s):  
Abdulwakil Olawale Saba ◽  
Nor Fariza Rasli ◽  
Ahmad Ismail ◽  
Syaizwan Zahmir Zulkifli ◽  
Intan Faraha A. Ghani ◽  
...  
Keyword(s):  
Fish Species ◽  
The Body ◽  
Introduced Fish ◽  
Aquatic Biodiversity ◽  
First Report ◽  
Body Patterns ◽  
Body Pattern

Invasive introduced fish species are well known for their deleterious impacts on aquatic biodiversity and environment. This study provides the first report on the occurrence of introduced Amazon sailfin catfish, Pterygoplichthys pardalis from the Gombak basin, Selangor, Malaysia, where the suckermouth catfish, Hypostomus plecostomus and vermiculated sailfin catfish, Pterygoplichthys disjunctivus had been previously reported. Besides, selected morphometric and meristic measurements between P. pardalis and P. disjunctivus from the Pusu River, Gombak basin were compared. Moreover, we also described two body patterns of the P. pardalis collected from the river. The body pattern which does not fit entirely with the known characteristics of P. pardalis or P. disjunctivus is suspected to be a result of hybridization between both species, but deeper study should be conducted to confirm this claim.

scholarly journals Contrasting coloration in terrestrial mammals

2008 ◽  
Vol 364 (1516) ◽  
pp. 537-548 ◽  
Author(s):  
Tim Caro
Keyword(s):  
Temperature Regulation ◽  
Functional Significance ◽  
The Body ◽  
Sexual Dichromatism ◽  
Black And White ◽  
Terrestrial Mammals ◽  
Background Matching ◽  
Disruptive Coloration ◽  
Colour Patterns ◽  
Pelage Coloration

Here I survey, collate and synthesize contrasting coloration in 5000 species of terrestrial mammals focusing on black and white pelage. After briefly reviewing alternative functional hypotheses for coloration in mammals, I examine nine colour patterns and combinations on different areas of the body and for each mammalian taxon to try to identify the most likely evolutionary drivers of contrasting coloration. Aposematism and perhaps conspecific signalling are the most consistent explanations for black and white pelage in mammals; background matching may explain white pelage. Evidence for contrasting coloration is being involved in crypsis through pattern blending, disruptive coloration or serving other functions, such as signalling dominance, lures, reducing eye glare or in temperature regulation has barely moved beyond anecdotal stages of investigation. Sexual dichromatism is limited in this taxon and its basis is unclear. Astonishingly, the functional significance of pelage coloration in most large charismatic black and white mammals that were new to science 150 years ago still remains a mystery.

scholarly journals Disruptive coloration provides camouflage independent of background matching

2006 ◽  
Vol 273 (1600) ◽  
pp. 2427-2432 ◽  
Author(s):  
H. Martin Schaefer ◽  
Nina Stobbe
Keyword(s):  
Body Shape ◽  
The Body ◽  
Cognitive Mechanisms ◽  
Proximate Mechanisms ◽  
Background Matching ◽  
Prey Recognition ◽  
Heterogeneous Habitats ◽  
Disruptive Coloration ◽  
Fitness Benefits ◽  
Better Than

Natural selection shapes the evolution of anti-predator defences, such as camouflage. It is currently contentious whether crypsis and disruptive coloration are alternative mechanisms of camouflage or whether they are interrelated anti-predator defences. Disruptively coloured prey is characterized by highly contrasting patterns to conceal the body shape, whereas cryptic prey minimizes the contrasts to background. Determining bird predation of artificial moths, we found that moths which were dissimilar from the background but sported disruptive patterns on the edge of their wings survived better in heterogeneous habitats than did moths with the same patterns inside of the wings and better than cryptic moths. Despite lower contrasts to background, crypsis did not provide fitness benefits over disruptive coloration on the body outline. We conclude that disruptive coloration on the edge camouflages its bearer independent of background matching. We suggest that this result is explainable because disruptive coloration is effective by exploiting predators' cognitive mechanisms of prey recognition and not their sensory mechanisms of signal detection. Relative to disruptive patterns on the body outline, disruptive markings on the body interior are less effective. Camouflage owing to disruptive coloration on the body interior is background-specific and is as effective as crypsis in heterogeneous habitats. Hence, we hypothesize that two proximate mechanisms explain the diversity of visual anti-predator defences. First, disruptive coloration on the body outline provides camouflage independent of the background. Second, background matching and disruptive coloration on the body interior provide camouflage, but their protection is background-specific.

scholarly journals Visual perception and camouflage response to 3-D backgrounds and cast shadows in the European cuttlefish Sepia officinalis

2021 ◽  
Author(s):  
Aliya El Nagar ◽  
Daniel Osorio ◽  
Sarah Zylinski ◽  
Steven M. Sait
Keyword(s):  
Retinal Image ◽  
The Body ◽  
Sepia Officinalis ◽  
Visual Depth ◽  
Depth Cues ◽  
Stage Process ◽  
Body Patterns ◽  
Camouflage Patterns ◽  
Large Repertoire ◽  
Body Pattern

To conceal themselves on the seafloor European cuttlefish Sepia officinalis express a large repertoire of body patterns. Scenes with 3-D relief are especially challenging because neither is it possible to directly recover visual depth from the 2-D retinal image, nor for the cuttlefish to alter its body shape to resemble nearby objects. Here we characterise cuttlefish's camouflage responses to 3-D relief, and to cast shadows, which are complementary depth cues. Animals were recorded in the presence of cylindrical objects of fixed (15mm) diameter, but varying in height, greyscale and strength of cast shadows, and to corresponding 2-D pictorial images. With the cylinders the cuttlefish expressed a ‘3-D’ body pattern, which is distinct from previously described Uniform, Mottle, and Disruptive camouflage patterns. This pattern was insensitive to variation in object height, contrast, and cast shadow, except when shadows were most pronounced, in which case the body patterns resembled those used on the 2-D backgrounds. This suggests that stationary cast shadows are not used as visual depth cues by cuttlefish, and that rather than directly matching the 2-D retinal image, the camouflage response is a two-stage process whereby the animal first classifies the physical environment and then selects an appropriate pattern. Each type of pattern is triggered by specific cues that may compete allowing the animal to select the most suitable camouflage, so the camouflage response is categorical rather than continuously variable. These findings give unique insight into how an invertebrate senses its visual environment to generate the body pattern response.

scholarly journals Perception of edges and visual texture in the camouflage of the common cuttlefish, Sepia officinalis

2008 ◽  
Vol 364 (1516) ◽  
pp. 439-448 ◽  
Author(s):  
S Zylinski ◽  
D Osorio ◽  
A.J Shohet
Keyword(s):  
The Body ◽  
Visual Environment ◽  
Sepia Officinalis ◽  
Visual Texture ◽  
Edge Information ◽  
The Common ◽  
Body Patterns ◽  
Mean Luminance ◽  
High Pass ◽  
Body Pattern

The cuttlefish, Sepia officinalis , provides a fascinating opportunity to investigate the mechanisms of camouflage as it rapidly changes its body patterns in response to the visual environment. We investigated how edge information determines camouflage responses through the use of spatially high-pass filtered ‘objects’ and of isolated edges. We then investigated how the body pattern responds to objects defined by texture (second-order information) compared with those defined by luminance. We found that (i) edge information alone is sufficient to elicit the body pattern known as Disruptive, which is the camouflage response given when a whole object is present, and furthermore, isolated edges cause the same response; and (ii) cuttlefish can distinguish and respond to objects of the same mean luminance as the background. These observations emphasize the importance of discrete objects (bounded by edges) in the cuttlefish's choice of camouflage, and more generally imply that figure–ground segregation by cuttlefish is similar to that in vertebrates, as might be predicted by their need to produce effective camouflage against vertebrate predators.

scholarly journals Integumentary Colour Allocation in the Stork Family (Ciconiidae) Reveals Short-Range Visual Cues for Species Recognition

Birds ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 138-146
Author(s):  
Eduardo J. Rodríguez-Rodríguez ◽  
Juan J. Negro
Keyword(s):  
Short Range ◽  
Visual Cues ◽  
Species Recognition ◽  
The Body ◽  
Whole Body ◽  
Divergent Evolution ◽  
Black And White ◽  
Extant Species ◽  
Chromatic Spectrum ◽  
Mixed Species Flocks

The family Ciconiidae comprises 19 extant species which are highly social when nesting and foraging. All species share similar morphotypes, with long necks, a bill, and legs, and are mostly coloured in the achromatic spectrum (white, black, black, and white, or shades of grey). Storks may have, however, brightly coloured integumentary areas in, for instance, the bill, legs, or the eyes. These chromatic patches are small in surface compared with the whole body. We have analyzed the conservatism degree of colouration in 10 body areas along an all-species stork phylogeny derived from BirdTRee using Geiger models. We obtained low conservatism in frontal areas (head and neck), contrasting with a high conservatism in the rest of the body. The frontal areas tend to concentrate the chromatic spectrum whereas the rear areas, much larger in surface, are basically achromatic. These results lead us to suggest that the divergent evolution of the colouration of frontal areas is related to species recognition through visual cue assessment in the short-range, when storks form mixed-species flocks in foraging or resting areas.

Three-alpha resonant state and its contribution in continuum spectrum

2006 ◽  
Vol 21 (31n33) ◽  
pp. 2351-2358
Author(s):  
C. Kurokawa ◽  
K. Katō
Keyword(s):  
Boundary Condition ◽  
Resonant State ◽  
Level Density ◽  
Complex Scaling ◽  
Scaling Method ◽  
Complex Scaling Method ◽  
Resonant States ◽  
Complex Eigenvalues ◽  
Three Body ◽  
The Continuum

The 3α resonant states of 12 C are investigated by taking into account the correct boundary condition for three-body resonant states. In order to show how the 3α resonant states having complex eigenvalues contribute to the real energy, we calculated the Continuum Level Density in the Complex Scaling Method.

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