Animal Camouflage: Mechanisms and Function

Contents......Page 7
Contributors......Page 10
1.1 Introduction......Page 14
1.2 Camouflage: a history of the idea......Page 16
1.3 The different types of camouflage......Page 17
1.3.1 Background matching......Page 20
1.3.2 Disruptive coloration......Page 21
1.3.4 Masquerade......Page 22
1.3.6 Distractive markings......Page 23
1.5 Acknowledgements......Page 24
2.2 Background matching and deception of perception......Page 30
2.3 Evidence for background matching......Page 31
2.4 Optimisation of background matching in visually variable backgrounds......Page 32
2.5 Testing the specialisation–compromise continuum of background matching......Page 35
2.6 Challenges of measuring the level of background matching......Page 37
2.7 Background matching and other means of camouflage......Page 40
2.9 Summary......Page 42
2.10 Acknowledgements......Page 43
3.1 Introduction......Page 47
3.2.1 Target colour patterns......Page 49
3.2.3 Experiment 1......Page 50
3.2.4 Experiment 2......Page 53
3.2.5 Experiment 3......Page 54
3.3.1 Experiment 1......Page 55
3.3.3 Experiment 3......Page 57
3.4 Discussion......Page 60
3.5 Summary......Page 63
3.6 Acknowledgements......Page 64
4.1 Introduction......Page 82
4.2 A history of the idea......Page 83
4.3 The visual properties of countershading related to habitat, activity and movement......Page 85
4.3.1 Habitat differences and activity related to the level of contrast between the dorsal and ventral surface......Page 86
4.3.3 Posture in relation to level of contrast between the dorsal and ventral surface......Page 87
4.4 The concealing function of countershading......Page 88
4.4.1 Direct tests of concealment......Page 89
4.4.2.1 Self-shadow concealment which results in improved background matching when viewed from the side......Page 91
4.4.2.2 Self-shadow concealment that flattens the form when viewed from the side......Page 92
4.4.2.3 Background matching when viewed from above or below......Page 94
4.6.1 Protection from ultraviolet radiation......Page 95
4.7 Summary......Page 96
4.9 References......Page 97
5.1 Introduction......Page 102
5.2 Yarg, Darg: operators for detection of convex domains......Page 103
5.2.1.2 Why detect zero-crossings of the gradient argument?......Page 104
5.3.1 Biological evidence for camouflage breaking by convexity detection......Page 106
5.3.2 Thayer\'s countershading against -based detection......Page 107
5.3.3 Neuronal implementation of  Darg......Page 109
5.4.2 Apatetic coloration in animals......Page 110
5.4.3 Countershading: an effective camouflage against  Darg......Page 111
5.5 Summary......Page 112
5.6 Acknowledgements......Page 113
6.1 Thayer\'s influence......Page 116
6.2 His discovery of countershading......Page 117
6.3 Art, science and sleight of hand......Page 118
6.5 His efforts beyond countershading......Page 120
6.6 Thayer\'s demonstrations......Page 123
6.7 An ironic conclusion......Page 125
6.8 Summary......Page 127
7.1.2 Behaviourally mediated crypsis: orientational alignment......Page 130
7.2.1 Study system and question......Page 131
7.3.2 Human predator system: testing the effect of orientation on crypsis......Page 132
7.3.3 Statistical analysis......Page 135
7.4.2 Human predator system: testing the effect of moth orientation on survivorship......Page 136
7.5 Discussion......Page 139
7.6.1 Future perspectives and sensory ecology......Page 141
7.6.2 Disruptive coloration and behaviourally mediated crypsis......Page 142
7.8 Acknowledgements......Page 143
8.1.2 Intensity borders......Page 147
8.1.4 Spectral information......Page 148
8.1.6 Summary and implications for camouflage......Page 150
8.2 Edge detection processes: disruption and camouflage......Page 151
8.2.1 \'Edge detectors’ in V1......Page 152
8.2.2 Stopping edge detectors responding to edges......Page 153
8.2.3 Making edge detectors respond to non-existent features......Page 154
8.3.1 Encoding of motion......Page 155
8.3.2 Motion camouflage......Page 157
8.4.1 How three-dimensional shapes are perceived......Page 159
8.4.1.1 Shape recovery......Page 160
8.4.1.3 Detection......Page 161
8.5.1 Search image and search target......Page 162
8.5.2 Search in natural scenes......Page 165
8.8 Acknowledgements......Page 167
9.1 Why have rapid adaptive camouflage?......Page 174
9.2.1 The UMD concept of parsimony, and a sensorimotor control hypothesis......Page 175
9.2.2 Descriptions and quantification of Uniform, Mottle and Disruptive patterns......Page 176
9.3 Bridging the continuum between background matching and disruptive coloration......Page 179
9.4.1 Key feature detection for pattern control......Page 181
9.4.3 Colour matching by a colour-blind cephalopod?......Page 183
9.5 Changeable skin: passive and active components that enable optical and physical malleability......Page 185
9.6 Masquerade and mimicry......Page 186
9.7 Night and motion camouflage......Page 187
9.8 Summary......Page 188
10.1 Vision and visual camouflage......Page 193
10.2.1 Introducing visual camouflage in Sepia......Page 195
10.2.2 Classifying cuttlefish body patterns......Page 196
10.3.1.1 Area and contrast......Page 198
10.3.1.2 Edges......Page 199
10.3.2 Detecting edges and objects......Page 200
10.3.3 Texture perception......Page 204
10.3.4 Depth and perspective......Page 206
10.4 Bringing it all together: integrating multiple visual cues......Page 208
10.6 Acknowledgements......Page 210
11.1 Introduction......Page 215
11.2 Light underwater......Page 220
11.3.1 Simple background matching and disruption: chromatically flat colours......Page 221
11.3.2 Simple background matching and disruption, but with saturated colours......Page 222
11.3.3 Less obvious camouflage: blue or yellow all over......Page 223
11.3.4 Yellow and blue together: within-fish colours for disruption or colour combination......Page 227
11.4.1 Camouflage with colour......Page 230
11.4.2 Transparency......Page 232
11.4.4 Ventral bioluminescence......Page 234
11.6 Summary......Page 235
11.7 Acknowledgements......Page 236
12.1 Introduction......Page 241
12.2.1 Morphological components of decoration behaviour......Page 242
12.2.2 Behavioural aspects of decorating......Page 243
12.2.3 Other forms of camouflage......Page 246
12.3.1.2 Preferential use of noxious or unpalatable decoration materials......Page 248
12.3.1.3 Spatial distribution of decoration......Page 249
12.3.2.1 Food storage......Page 250
12.4 Decorator crabs and the evolution of camouflage......Page 251
12.4.1.2 Intersexual and ontogenetic changes and the costs of camouflage......Page 252
12.4.2 Interspecific variation: phylogenetic approaches......Page 254
12.4.2.2 Evolution of alternative camouflage strategies......Page 256
12.5.1 Origins of decoration......Page 257
12.5.4 Links between development, behaviour and evolution......Page 259
12.6 Conclusions......Page 260
12.7 Summary......Page 261
13 Camouflage in colour-changing animals......Page 266
13.1 Camouflage strategies in colour-changing animals......Page 268
13.2.1 Camouflage and conspicuousness......Page 271
13.2.2 The role of thermoregulation......Page 273
13.3 Limits and costs of colour change......Page 274
13.4 Why did colour change evolve?......Page 276
13.5 Conclusion......Page 277
13.7 Acknowledgements......Page 278
14.2 Web design, colour and visual environment......Page 283
14.3.1 Silk decorations......Page 285
14.3.2 Detritus decorations......Page 287
14.4 Spider coloration: generalities......Page 288
14.5 Spider coloration: pigments responsible for colour change......Page 289
14.6 Spiders mimic ants......Page 294
14.7 Future prospects......Page 296
14.9 Acknowledgements......Page 297
15.1 Introduction......Page 304
15.3 The evolutionarily stable strategies of live backgrounds......Page 305
15.3.1.1 Seeker behaviour......Page 306
15.3.1.3 Background fitness functions......Page 308
15.3.2 Ambush predators feed on mutualists of the live background......Page 309
15.3.3 Ambush predators feed on species that harm the background......Page 311
15.3.4 Herbivores and parasites attacked by pursuit predators......Page 312
15.4.1 Coevolution of live backgrounds with predators and prey......Page 313
15.4.2 The plausibility of background evolution......Page 314
15.4.3 Where is background evolution most likely to occur?......Page 315
15.5 Prospects......Page 316
15.8.1.1 Seeker behaviour......Page 317
15.8.1.2 Hider behaviour......Page 320
15.8.1.3 Background fitness functions......Page 322
15.8.4 Herbivores and parasites attacked by pursuit predators......Page 323
15.8.4.1.1 Other atypical cases......Page 324
16.1.1 Black-and-white coloration......Page 327
16.1.2 Theories of coloration......Page 328
16.2.1 Black-and-white quills......Page 330
16.2.2 Horizontal bands of white fur on head, nape or dorsum, or on tail or in combination......Page 331
16.2.3 Black-and-white face masks......Page 333
16.2.4 Contrasting necks and chests......Page 335
16.2.5 Body with blocks of black-and-white fur......Page 336
16.2.6 Black body with white spots or blotches......Page 337
16.2.8 Contrasting feet, legs and rumps......Page 338
16.2.9 Black-and-white tails......Page 340
16.2.10 White mammals......Page 341
16.3.1 Contrasting black dorsum and white ventrum......Page 342
16.3.3 White head or chin......Page 344
16.4 Sexual dichromatism......Page 345
16.6 Summary......Page 350
16.7 Acknowledgements......Page 352
17.1 Introduction......Page 359
17.2 Sound......Page 360
17.3 Olfaction......Page 365
17.4 Electricity......Page 371
17.5 Hydrodynamic crypsis......Page 372
17.6 Substrate vibrations......Page 373
17.8 Summary......Page 374
Index......Page 380