Given that the aperture effect relies upon the presence of high-contrast stripes across large parts of the visual field, checked patterns should not disrupt optic flow (and therefore visually guided flight control) through this mechanism.

Cristobal Serrano, Spain. "Horseflies in Africa carry diseases that are lethal to members of the horse family - the. Start your Independent Premium subscription today.

Most landings were on black and grey rugs, an average of 2–3 min−1, and these rates were significantly greater than landing rates on patterned rugs that averaged approximately 0.2 min−1 (post hoc ‘multi-compare' with Bonferroni correction p < 0.001). However, we cannot yet distinguish alternative possibilities that may affect flight control or decision-making in horsefly host-finding behaviour. Reconstructions of the three-dimensional flight trajectories were then smoothed with a three-point moving average.

With conditions of perfect visibility and beautiful sunlight, Christian took this portrait of a nurse shark gliding through the ocean off the coast of Bimini in the Bahamas. Something similar could be happening as flies approach zebra stripes.

This adult humpback whale balanced in mid-water, headon and sound asleep was photographed in Vava’u, Kingdom of Tonga. When we examined flight speeds as horseflies approached rugs, we found that flies flew more slowly towards grey than towards the three patterned rugs, particularly when they were between 0.1 and 0.6 m away from the host (Kruskal–Wallis with multi-compare post hoc and Bonferroni correction for 0.1 to 0.6 m data, p < 0.05; figure 4a). Illustration of the main test hypotheses. Figure 5. Connor Stefanison / Natural History Museum.

To minimize the number of repeat measurements from single flies for each rug type, sampling effort from the videos was spread as evenly as possible over the full seven-day duration of the video-recording period. Snapped from a helicopter, this isolated tree stands in a cultivated field on the edge of a tropical forest on Kauai, Hawaii. (a) Speed versus distance during fly approach, colour coded according to (b). Slow turns were significantly more frequent near the grey than near the patterned rugs, whereas fast turns were significantly less frequent around grey than the striped rugs (figure 5c). Second, the distances to which flies approached the different rug patterns (figure 3) refute the aperture effect hypothesis, because no differences were observed between checked and striped rugs. Figure 4. (b) Horsefly landing rate on each of the five patterned rugs. The distribution of motion vectors across each of these scenes is represented in the polar histograms below. To place the trajectory data in the context of the target host, a three-dimensional mesh model of an average-sized horse was placed in the virtual space alongside the fly trajectory and manoeuvred to align with markers digitized on the front and rear regions of the original horse. Are you sure you want to delete this comment? (b) Closest recorded distance of each fly to the horse (figure 2 for conventions). Matthew Maran, UK. (b) Motion maps generated from the same down-sampled images expanding from the central landing point. TinMan Lee, USA. Our observations that flies avoided checked patterns in a similar way to stripes refutes the hypothesis that stripes disrupt optic flow via the aperture effect, which critically demands parallel striped patterns.

It took David some time to approach the clam, fearing it would sense his movements and snap shut! Cows painted like zebras can fend off flies better than their plain-coated counterparts, Make like a zebra to avoid insect bites, scientists say. "Not only do these exciting studies bring us closer to understanding one of the world's most iconic and photogenic species, they will be of great interest to farmers attempting to reduce the damage caused by fly bites and even general horse-wear companies," said Tim Caro, a senior co-author of the study and a professor at the University of Bristol's School of Biological Sciences, in a release. LONDON (AP) — Zebra stripes are dazzling — particularly to flies. Crucially, we included a checked rug (which would generate radially symmetric optic flow patterns) as well as horizontally and vertically striped patterns to separate the aperture effect from the other hypotheses. Franco Banfi, Switzerland. The fashionable patterned coat protects the animal from horsefly bites by disorienting the flies during the landing process, research has shown. Here, we sought to determine whether the first of these ideas, the disruption of the radial symmetry of optic flow via the aperture effect, is responsible for the anti-biting fly mechanism of zebra stripes. Turing patterns in development: what about the horse part? Create a commenting name to join the debate, There are no Independent Premium comments yet - be the first to add your thoughts, There are no comments yet - be the first to add your thoughts. These stripes will likely disrupt the pattern of optic flow so that it becomes dominated by motion cues in directions perpendicular to stripe orientation (figure 1bii). (a) Dorsoventral (top) and anteroposterior (bottom) views of 107 fly trajectories plotted around the horse location (see also electronic supplementary material, figure S2 and movie S3). Approach speed of flies to each rug type. The manmade straight lines of the ploughed furrows are interrupted beautifully by nature’s more unruly wild pattern of tree branches.

Zebra-striped cows might not look like the African wild horse, but they get the same benefits from their coloring. If the address matches an existing account you will receive an email with instructions to reset your password. There were no differences in landing frequencies between either of the uniform rugs (p = 1), or between patterned rugs (p = 1). Previously, the same researchers had shown that blood-sucking horseflies would approach horses in striped rugs as often as plain rugs, but then failed to land or slow down when they got close.
Antonio Leiva Sanchez / Natural History Museum. The unusual and striking colouration pattern of the three species of extant zebra (Equus sp.) The rays appear to paint the spray of the waterfall and create a truly magical picture. They also stop blood-sucking flies from landing on the animal and protect them from deadly diseases, according to new research.

Scientists place sheets on horses to test theory, Find your bookmarks in your Independent Premium section, under my profile. Next, we used the reconstructed three-dimensional trajectories (figure 3a and electronic supplementary material, figures S2–S3) to examine horsefly behaviour around rugs with equivalent luminance (i.e.
You can unsubscribe at any time and we'll never share your details to third parties. “We showed that horse flies approach zebras and uniformly coloured horses at similar rates but that they fail to land on zebras – or striped horse coats – because they fail to decelerate properly,” said behavioural ecologist Tim Caro, who led the research which was published in the journal PLOS ONE. Although stripes did not deter flies from a distance, they landed on zebras less than a quarter as often as they did on horses. Usually, several different flies landed on horses per observation period, although repeat landings by single horseflies were documented from the flight trajectories [13].


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