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Tan M, Zhang S, Stevens M, Li D, Tan EJ. Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals. Biol Rev Camb Philos Soc 2024; 99:778-796. [PMID: 38174819 DOI: 10.1111/brv.13044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024]
Abstract
Motion is a crucial part of the natural world, yet our understanding of how animals avoid predation whilst moving remains rather limited. Although several theories have been proposed for how antipredator defence may be facilitated during motion, there is often a lack of supporting empirical evidence, or conflicting findings. Furthermore, many studies have shown that motion often 'breaks' camouflage, as sudden movement can be detected even before an individual is recognised. Whilst some static camouflage strategies may conceal moving animals to a certain extent, more emphasis should be given to other modes of camouflage and related defences in the context of motion (e.g. flicker fusion camouflage, active motion camouflage, motion dazzle, and protean motion). Furthermore, when motion is involved, defence strategies are not necessarily limited to concealment. An animal can also rely on motion to mislead predators with regards to its trajectory, location, size, colour pattern, or even identity. In this review, we discuss the various underlying antipredator strategies and the mechanisms through which they may be linked to motion, conceptualising existing empirical and theoretical studies from two perspectives - concealing and misleading effects. We also highlight gaps in our understanding of these antipredator strategies, and suggest possible methodologies for experimental designs/test subjects (i.e. prey and/or predators) and future research directions.
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Affiliation(s)
- Min Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Shichang Zhang
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Eunice J Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Division of Science, Yale-NUS College, 16 College Avenue West, Singapore, 138527, Singapore
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Tan M, Chan JYO, Yu L, Tan EJ, Li D. Background matching can reduce responsiveness of jumping spiders to stimuli in motion. J Exp Biol 2024; 227:jeb246092. [PMID: 38054359 PMCID: PMC10906486 DOI: 10.1242/jeb.246092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023]
Abstract
Motion and camouflage were previously considered to be mutually exclusive, as sudden movements can be easily detected. Background matching, for instance, is a well-known, effective camouflage strategy where the colour and pattern of a stationary animal match its surrounding background. However, background matching may lose its efficacy when the animal moves, as the boundaries of the animal become more defined against its background. Recent evidence shows otherwise, as camouflaged objects can be less detectable than uncamouflaged objects even while in motion. Here, we explored whether the detectability of computer-generated stimuli varies with the speed of motion, background (matching and unmatching) and size of stimuli in six species of jumping spiders (Araneae: Salticidae). Our results showed that, in general, the responsiveness of all six salticid species tested decreased with increasing stimulus speed regardless of whether the stimuli were conspicuous or camouflaged. Importantly, salticid responses to camouflaged stimuli were significantly lower compared with those to conspicuous stimuli. There were significant differences in motion detectability across species when the stimuli were conspicuous, suggesting differences in visual acuity in closely related species of jumping spiders. Furthermore, small stimuli elicited significantly lower responses than large stimuli across species and speeds. Our results thus suggest that background matching is effective even when stimuli are in motion, reducing the detectability of moving stimuli.
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Affiliation(s)
- Min Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore117543
| | - Jeremiah Y. O. Chan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore117543
| | - Long Yu
- Centre for Behavioural Ecology & Evolution, College of Life Sciences, Hubei University, Wuhan 430062, Hubei, China
| | - Eunice J. Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore117543
- Division of Science, Yale-NUS College, 16 College Avenue West, Singapore138527
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore117543
- Centre for Behavioural Ecology & Evolution, College of Life Sciences, Hubei University, Wuhan 430062, Hubei, China
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Lambert PJ, Herbert-Read JE, Ioannou CC. The measure of spatial position within groups that best predicts predation risk depends on group movement. Proc Biol Sci 2021; 288:20211286. [PMID: 34521249 PMCID: PMC8441135 DOI: 10.1098/rspb.2021.1286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/23/2021] [Indexed: 11/12/2022] Open
Abstract
Both empirical and theoretical studies show that an individual's spatial position within a group can impact the risk of being targeted by predators. Spatial positions can be quantified in numerous ways, but there are no direct comparisons of different spatial measures in predicting the risk of being targeted by real predators. Here, we assess these spatial measures in groups of stationary and moving virtual prey being attacked by three-spined sticklebacks (Gasterosteus aculeatus). In stationary groups, the limited domain of danger best predicted the likelihood of attack. In moving groups, the number of near neighbours was the best predictor but only over a limited range of distances within which other prey were counted. Otherwise, measures of proximity to the group's edge outperformed measures of local crowding in moving groups. There was no evidence that predators preferentially attacked the front or back of the moving groups. Domains of danger without any limit, as originally used in the selfish herd model, were also a poor predictor of risk. These findings reveal that the collective properties of prey can influence how spatial position affects predation risk, via effects on predators' targeting. Selection may therefore act differently on prey positioning behaviour depending on group movement.
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Affiliation(s)
- Poppy J. Lambert
- Comparative Cognition Unit, Messerli Research Institute, University of Veterinary Medicine Vienna, University of Vienna, Medical University of Vienna, Vienna, Austria
| | - James E. Herbert-Read
- Department of Zoology, University of Cambridge, Cambridge, UK
- Aquatic Ecology, Department of Biology, Lund University, Lund, Sweden
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Matchette SR, Cuthill IC, Cheney KL, Marshall NJ, Scott-Samuel NE. Underwater caustics disrupt prey detection by a reef fish. Proc Biol Sci 2020; 287:20192453. [PMID: 32228405 PMCID: PMC7209061 DOI: 10.1098/rspb.2019.2453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Natural habitats contain dynamic elements, such as varying local illumination. Can such features mitigate the salience of organism movement? Dynamic illumination is particularly prevalent in coral reefs, where patterns known as 'water caustics' play chaotically in the shallows. In behavioural experiments with a wild-caught reef fish, the Picasso triggerfish (Rhinecanthus aculeatus), we demonstrate that the presence of dynamic water caustics negatively affects the detection of moving prey items, as measured by attack latency, relative to static water caustic controls. Manipulating two further features of water caustics (sharpness and scale) implies that the masking effect should be most effective in shallow water: scenes with fine scale and sharp water caustics induce the longest attack latencies. Due to the direct impact upon foraging efficiency, we expect the presence of dynamic water caustics to influence decisions about habitat choice and foraging by wild prey and predators.
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Affiliation(s)
- S R Matchette
- School of Biological Sciences, University of Bristol, Tyndall Avenue, Bristol BS8 1TQ, UK.,School of Psychological Science, University of Bristol, Woodland Road, Bristol BS8 1TN, UK
| | - I C Cuthill
- School of Biological Sciences, University of Bristol, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - K L Cheney
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia.,School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - N J Marshall
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - N E Scott-Samuel
- School of Psychological Science, University of Bristol, Woodland Road, Bristol BS8 1TN, UK
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Smart IE, Cuthill IC, Scott-Samuel NE. In the corner of the eye: camouflaging motion in the peripheral visual field. Proc Biol Sci 2020; 287:20192537. [PMID: 31937225 DOI: 10.1098/rspb.2019.2537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Most animals need to move, and motion will generally break camouflage. In many instances, most of the visual field of a predator does not fall within a high-resolution area of the retina and so, when an undetected prey moves, that motion will often be in peripheral vision. We investigate how this can be exploited by prey, through different patterns of movement, to reduce the accuracy with which the predator can locate a cryptic prey item when it subsequently orients towards a target. The same logic applies for a prey species trying to localize a predatory threat. Using human participants as surrogate predators, tasked with localizing a target on peripherally viewed computer screens, we quantify the effects of movement (duration and speed) and target pattern. We show that, while motion is certainly detrimental to camouflage, should movement be necessary, some behaviours and surface patterns reduce that cost. Our data indicate that the phenotype that minimizes localization accuracy is unpatterned, having the mean luminance of the background, does not use a startle display prior to movement, and has short (below saccadic latency), fast movements.
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Affiliation(s)
- Ioan E Smart
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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Kodandaramaiah U, Palathingal S, Bindu Kurup G, Murali G. What makes motion dazzle markings effective against predation? Behav Ecol 2019. [DOI: 10.1093/beheco/arz154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Motion dazzle markings comprise patterns such as stripes and zig-zags that are postulated to protect moving prey by making predators misjudge the prey’s speed or trajectory. Recent experiments have provided conflicting results on their effect on speed perception and attack success. We focus on motion dazzle stripes and investigate the influence of four parameters—stripe orientation, stripe contrast, target size, and target speed—on perceived speed and attack success using a common experimental paradigm involving human “predators” attacking virtual moving targets on a computer touchscreen. We found that high-contrast stripes running parallel or perpendicular to the direction of motion reduce attack success compared to conspicuous uniform targets. Surprisingly, parallel stripes induced underestimation of speed, while perpendicular stripes induced overestimation of speed in relation to uniform black, suggesting that misjudgment of speed per se is sufficient to reduce attack accuracy. Across all the experiments, we found some support for parallel stripes inducing underestimation of target speed but these stripes reduced attack success only when targets were small, moved at an intermediate speed, and had high internal contrast. We suggest that prey features (e.g., size or speed) are an important determinant of capture success and that distortion of speed perception by a color pattern does not necessarily translate to reduced capture success of the prey. Overall, our results support the idea that striped patterns in prey animals can reduce capture in motion but are effective under a limited set of conditions.
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Affiliation(s)
- Ullasa Kodandaramaiah
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
| | - Shuaib Palathingal
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India
| | - Gayathri Bindu Kurup
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
| | - Gopal Murali
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
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