Motion dazzle and camouflage as distinct anti-predator defenses. BMC Biol 9:81

Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
BMC Biology (Impact Factor: 7.98). 11/2011; 9(1):81. DOI: 10.1186/1741-7007-9-81
Source: PubMed


Camouflage patterns that hinder detection and/or recognition by antagonists are widely studied in both human and animal contexts. Patterns of contrasting stripes that purportedly degrade an observer's ability to judge the speed and direction of moving prey ('motion dazzle') are, however, rarely investigated. This is despite motion dazzle having been fundamental to the appearance of warships in both world wars and often postulated as the selective agent leading to repeated patterns on many animals (such as zebra and many fish, snake, and invertebrate species). Such patterns often appear conspicuous, suggesting that protection while moving by motion dazzle might impair camouflage when stationary. However, the relationship between motion dazzle and camouflage is unclear because disruptive camouflage relies on high-contrast markings. In this study, we used a computer game with human subjects detecting and capturing either moving or stationary targets with different patterns, in order to provide the first empirical exploration of the interaction of these two protective coloration mechanisms.
Moving targets with stripes were caught significantly less often and missed more often than targets with camouflage patterns. However, when stationary, targets with camouflage markings were captured less often and caused more false detections than those with striped patterns, which were readily detected.
Our study provides the clearest evidence to date that some patterns inhibit the capture of moving targets, but that camouflage and motion dazzle are not complementary strategies. Therefore, the specific coloration that evolves in animals will depend on how the life history and ontogeny of each species influence the trade-off between the costs and benefits of motion dazzle and camouflage.

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    • "Staudinger et al. (2013) also show that cuttlefishes adapt their cryptic behaviour according to the presence of various teleost predators. Multiple camouflaging techniques and anti-predator behaviours, such as the 'moving rock' are synergistically combined to yield the best cryptic result (Norman et al., 2001; Stevens et al., 2011). However, the question of camouflage and background matching during motion remains open. "
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    ABSTRACT: A moving object is considered conspicuous because of the movement itself. Once moving from one background to another, even dynamic camouflage experts such as cephalopods, should sacrifice their extraordinary camouflage. Therefore, minimizing detection at this stage is crucial and highly beneficial. In this study we describe a background-matching mechanism during movement, which aids the cuttlefish to downplay its presence throughout movement. In situ behavioural experiments using video and image analysis, revealed a delayed, sigmoidal, colour-changing mechanism during movement of Sepia officinalis across a uniform black and grey backgrounds, which we describe below. This is a fist and important step in understanding dynamic camouflage during movement, while the new behavioural mechanism may be incorporated and applied to any dynamic camouflaging animal or man-made system on the move.
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    • "While there have now been several studies considering both the hypothesis of motion dazzle and more generally how patterning affects perceptual and behavioural judgements when in motion (reviewed in Table 1), there is still debate as to which strategies are optimal and what aspects of a target’s pattern are important in determining capture difficulty. In this study, we use human prey capture experiments similar to those conducted by Stevens and colleagues [17,21] to investigate these questions. We compare putative ‘motion dazzle’ transverse striped targets, different types of cryptic stimuli (uniform luminance matched grey and background matching targets) and highly conspicuous white targets to determine how these different patterning types compare in difficulty of capture. "
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    ABSTRACT: Background Stripes and other high contrast patterns found on animals have been hypothesised to cause ¿motion dazzle¿, a type of defensive coloration that operates when in motion, causing predators to misjudge the speed and direction of object movement. Several recent studies have found some support for this idea, but little is currently understood about the mechanisms underlying this effect. Using humans as model `predators¿ in a touch screen experiment we investigated further the effectiveness of striped targets in preventing capture, and considered how stripes compare to other types of patterning in order to understand what aspects of target patterning are important in making a target difficult to capture.ResultsWe find that striped targets are among the most difficult to capture, but that other patterning types are also highly effective at preventing capture in this task. Several target types, including background sampled targets and targets with a `spot¿ on were significantly easier to capture than striped targets. We also show differences in capture attempt rates between different target types, but we find no differences in learning rates between target types.Conclusions We conclude that striped targets are effective in preventing capture, but are not uniquely difficult to catch, with luminance matched grey targets also showing a similar capture rate. We show that key factors in making capture easier are a lack of average background luminance matching and having trackable `features¿ on the target body. We also find that striped patterns are attempted relatively quickly, despite being difficult to catch. We discuss these findings in relation to the motion dazzle hypothesis and how capture rates may be affected more generally by pattern type.
    Full-text · Article · Sep 2014 · BMC Evolutionary Biology
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    • "dated . There is likely to be a trade - off between animal conspicuousness and movement ; for example , motion dazzle markings are highly conspicuous when prey are stationary but provide protection when moving . In contrast , camouflage provides protection when station - ary , but the same markings may appear conspicuous when the ani - mal moves ( Stevens et al . 2011 ) . This may explain why most prey become immobile or " freeze " when threatened . A study on cuttle - fish found that individuals produced low - contrast patterns when moving , suggesting that the high - contrast patterns in motion dazzle may not impede capture ( Zylinski et al . 2009a ) . However , a target with markings that provide "

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