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 Outline and surface disruption in animal camouflage

2008 ◽  
Vol 276 (1657) ◽  
pp. 781-786 ◽  
Author(s):  
Martin Stevens ◽  
Isabel S Winney ◽  
Abi Cantor ◽  
Julia Graham
Keyword(s):  
Body Shape ◽  
Luminance Contrast ◽  
The Body ◽  
Maximum Effect ◽  
High Contrast ◽  
High Luminance ◽  
Effective Surface ◽  
Avian Predators ◽  
Disruptive Coloration ◽  
Visual Mechanism

Camouflage is an important strategy in animals to prevent predation. This includes disruptive coloration, where high-contrast markings placed at an animal's edge break up the true body shape. Successful disruption may also involve non-marginal markings found away from the body outline that create ‘false edges’ more salient than the true body form (‘surface disruption’). However, previous work has focused on breaking up the true body outline, not on surface disruption. Furthermore, while high contrast may enhance disruption, it is untested where on the body different contrasts should be placed for maximum effect. We used artificial prey presented to wild avian predators in the field, to determine the effectiveness of surface disruption, and of different luminance contrast placed in different prey locations. Disruptive coloration was no more effective when comprising high luminance contrast per se , but its effectiveness was dramatically increased with high-contrast markings placed away from the body outline, creating effective surface disruption. A model of avian visual edge processing showed that surface disruption does not make object detection more difficult simply by creating false edges away from the true body outline, but its effect may also be based on a different visual mechanism. Our study has implications for whether animals can combine disruptive coloration with other ‘conspicuous’ signalling strategies.

scholarly journals Empirical tests of the role of disruptive coloration in reducing detectability

2007 ◽  
Vol 274 (1615) ◽  
pp. 1325-1331 ◽  
Author(s):  
Stewart Fraser ◽  
Alison Callahan ◽  
Dana Klassen ◽  
Thomas N Sherratt
Keyword(s):  
Field Experiments ◽  
Human Subjects ◽  
Common Features ◽  
Background Matching ◽  
Disruptive Coloration ◽  
Oak Trees ◽  
Empirical Tests ◽  
Body Shapes ◽  
Better Than

Disruptive patterning is a potentially universal camouflage technique that is thought to enhance concealment by rendering the detection of body shapes more difficult. In a recent series of field experiments, artificial moths with markings that extended to the edges of their ‘wings’ survived at higher rates than moths with the same edge patterns inwardly displaced. While this result seemingly indicates a benefit to obscuring edges, it is possible that the higher density markings of the inwardly displaced patterns concomitantly reduced their extent of background matching. Likewise, it has been suggested that the mealworm baits placed on the artificial moths could have created differential contrasts with different moth patterns. To address these concerns, we conducted controlled trials in which human subjects searched for computer-generated moth images presented against images of oak trees. Moths with edge-extended disruptive markings survived at higher rates, and took longer to find, than all other moth types, whether presented sequentially or simultaneously. However, moths with no edge markings and reduced interior pattern density survived better than their high-density counterparts, indicating that background matching may have played a so-far unrecognized role in the earlier experiments. Our disruptively patterned non-background-matching moths also had the lowest overall survivorship, indicating that disruptive coloration alone may not provide significant protection from predators. Collectively, our results provide independent support for the survival value of disruptive markings and demonstrate that there are common features in human and avian perception of camouflage.

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 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.

Updating long-held assumptions about fat stigma: For women, body shape plays a critical role

2020 ◽  
Author(s):  
Jaimie Krems ◽  
Steven L. Neuberg
Keyword(s):  
Body Shape ◽  
Critical Role ◽  
The Body ◽  
Theoretical Assumption ◽  
Obesity Stigma ◽  
Obese Female ◽  
Three Samples ◽  
Female Bodies ◽  
Different Parts ◽  
Fat Stigma

Heavier bodies—particularly female bodies—are stigmatized. Such fat stigma is pervasive, painful to experience, and may even facilitate weight gain, thereby perpetuating the obesity-stigma cycle. Leveraging research on functionally distinct forms of fat (deposited on different parts of the body), we propose that body shape plays an important but largely underappreciated role in fat stigma, above and beyond fat amount. Across three samples varying in participant ethnicity (White and Black Americans) and nation (U.S., India), patterns of fat stigma reveal that, as hypothesized, participants differently stigmatized equally-overweight or -obese female targets as a function of target shape, sometimes even more strongly stigmatizing targets with less rather than more body mass. Such findings suggest value in updating our understanding of fat stigma to include body shape and in querying a predominating, but often implicit, theoretical assumption that people simply view all fat as bad (and more fat as worse).

Chaos in body–vortex interactions

2010 ◽  
Vol 466 (2119) ◽  
pp. 1871-1891 ◽  
Author(s):  
Johan Roenby ◽  
Hassan Aref
Keyword(s):  
Body Shape ◽  
Mass Density ◽  
Relative Equilibrium ◽  
Large Body ◽  
Point Vortex ◽  
Cylindrical Body ◽  
The Body ◽  
Body Motion ◽  
Single Vortex ◽  
Vortex Interactions

The model of body–vortex interactions, where the fluid flow is planar, ideal and unbounded, and the vortex is a point vortex, is studied. The body may have a constant circulation around it. The governing equations for the general case of a freely moving body of arbitrary shape and mass density and an arbitrary number of point vortices are presented. The case of a body and a single vortex is then investigated numerically in detail. In this paper, the body is a homogeneous, elliptical cylinder. For large body–vortex separations, the system behaves much like a vortex pair regardless of body shape. The case of a circle is integrable. As the body is made slightly elliptic, a chaotic region grows from an unstable relative equilibrium of the circle-vortex case. The case of a cylindrical body of any shape moving in fluid otherwise at rest is also integrable. A second transition to chaos arises from the limit between rocking and tumbling motion of the body known in this case. In both instances, the chaos may be detected both in the body motion and in the vortex motion. The effect of increasing body mass at a fixed body shape is to damp the chaos.

scholarly journals Sea stars generate downforce to stay attached to surfaces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mark Hermes ◽  
Mitul Luhar
Keyword(s):  
Body Shape ◽  
Control Volume ◽  
Water Channel ◽  
Morphological Plasticity ◽  
The Body ◽  
Sea Star ◽  
Sea Stars ◽  
Hydrodynamic Loads ◽  
Spherical Dome ◽  
Star Models

AbstractIntertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.

scholarly journals “ALL IN ONE OR (W)HOLE IN ONE REPAIR” for Adult Total Brachial Plexus Palsy

2021 ◽  
Author(s):  
V. Purushothaman ◽  
K. Vinoth Kumar ◽  
Sabari Girish Ambat ◽  
R. Venkataswami
Keyword(s):  
Brachial Plexus ◽  
Hand Function ◽  
The Body ◽  
Salvage Procedure ◽  
Brachial Plexus Palsy ◽  
Nerve Reconstruction ◽  
Muscle Transfer ◽  
Young Males ◽  
Elbow Function ◽  
Better Than

Abstract Background Total brachial plexus palsy (TBPP) accounts for nearly 50% of all brachial plexus injuries. Since achieving a good functional hand was almost impossible, the aim was settled to get a good shoulder and elbow function. It was Gu, who popularized the concept of utilizing contralateral C7 (CC7) with vascularized ulnar nerve graft (VUNG) to get some hand function. We have modified it to suit our patients by conducting it as a single-stage procedure, thereby trying to get a functional upper limb. Methods From 2009 to 2014, we had 20 TBPP patients. We feel nerve reconstruction is always better than any other salvage procedure, including free muscle transfer. We modified Gu's concept and present our concept of total nerve reconstruction as “ALL IN ONE OR (W)HOLE IN ONE REPAIR.” Results All patients able to move their reconstructed limbs independently or with the help of contralateral limbs. Three patients developed hook grip and one patient was able to incorporate limbs to do bimanual jobs. One important observation is that all the reconstructed limbs regain the bulk, and to a certain extent, the attitude and appearance looks normal, as patients no longer hide it or hang it in a sling. Conclusion Adult brachial plexus injury itself is a devastating injury affecting young males. By doing this procedure, the affected limb is not dissociated from the rest of the body and rehabilitation can be aimed to get a supportive limb.

scholarly journals Trinidadian guppies use a social heuristic that can support cooperation among non-kin

2020 ◽  
Vol 287 (1934) ◽  
pp. 20200487 ◽  
Author(s):  
Safi K. Darden ◽  
Richard James ◽  
James M. Cave ◽  
Josefine Bohr Brask ◽  
Darren P. Croft
Keyword(s):  
Poecilia Reticulata ◽  
Social Space ◽  
Inclusive Fitness ◽  
Single Point ◽  
Theoretical Work ◽  
Evolution Of Cooperation ◽  
Social Partner ◽  
Proximate Mechanisms ◽  
Cognitive Limitations ◽  
Fitness Benefits

Cooperation among non-kin is well documented in humans and widespread in non-human animals, but explaining the occurrence of cooperation in the absence of inclusive fitness benefits has proven a significant challenge. Current theoretical explanations converge on a single point: cooperators can prevail when they cluster in social space. However, we know very little about the real-world mechanisms that drive such clustering, particularly in systems where cognitive limitations make it unlikely that mechanisms such as score keeping and reputation are at play. Here, we show that Trinidadian guppies ( Poecilia reticulata ) use a ‘walk away’ strategy, a simple social heuristic by which assortment by cooperativeness can come about among mobile agents. Guppies cooperate during predator inspection and we found that when experiencing defection in this context, individuals prefer to move to a new social environment, despite having no prior information about this new social group. Our results provide evidence in non-human animals that individuals use a simple social partner updating strategy in response to defection, supporting theoretical work applying heuristics to understanding the proximate mechanisms underpinning the evolution of cooperation among non-kin.

Sign in / Sign up

Export Citation Format

Share Document