Motion dazzle markings:

Animals have several strategies to avoid predation, and mimicry and camouflage are widely used, and seem to work well for lots of animals. There is one downside using these strategies though, and it is related to movement. When an animal moves, it is exposing itself, making it easy for a predator to spot it. This creates a huge challenge for animals that are moving around to find food sources, and is even more challenging as the animal increases in size, because it is then harder to hide, or make the body blend in with the background. To cope with this, it has been proposed that a good strategy to avoid predation might be something called motion dazzling. So what is this exactly?

Motion dazzle patterns are very bold and visible patterns, that are assumed to create confusion and mislead the predator. During experiments(Stevens, M, Yule, DH, Ruxton, GD 2008) scientists have proved such patterns to be efficient because they make it difficult for the predator to estimate speed, distance and direction. Patterns are proved to be more efficient if the speed increases, so it is likely to be more present in fast moving animals. If a predator- a lion, misjudges the distance to a zebra for example, this might lead to an attack ending in disaster. If a predator misjudges a distance, it might miss the target by centimeters to meters, depending on target, the patterns and the speed, but as long as misjudging is present, there is opportunities for the prey to escape, and this is likely the reason for why these patterns have evolved.

There hasn't been a lot of research on this subject, but there were a couple of researchers that worked with this and got supporting results for motion dazzling being efficient(Stevens, M, Yule, DH, Ruxton, GD 2008). They used a computer program to test if people were more or less likely to hit a target when the target wore stripes and zig- zag patterns, and they found that such patterns made it more difficult to succeed. Since human and vertebrate eyes work pretty much in the same fashion, it is likely that this can be transfered to nature as well.

There are found animals with these dazzling patterns among several taxa, including vertebrates, fishes, reptiles and some insects.

A highly debated animal within this area is the zebra. It has been believed for a long time that the stripes the zebra possesses are a good example of a motion dazzle pattern. Zebras are big animals, that are mostly found on grassland areas with open landscape where there is no place to hide. They have to move a lot during the day, which makes it even easier to detect them. Because camouflage is not really an option for these animals, it would make sense that the stripes would protect them against predators, making it harder to catch them due to misjudging as explained earlier. When they live in a herd, the stripes could even create more confusion. Focusing on one individual will be hard when all zebras have striped patterns that seem to blend in and mix with each other, the outline of an individual will then be hard to see. But one research project found little evidence for this being the case(Caro et al. 2014) when they looked at the distribution of zebras and big predators, and how efficiently the predators were at catching prey.

In general there is a lot of assumptions regarding this area, and little research done. It is hard to conclude if patterns we see are a result of evolution related to motion dazzling, or if there are entirely other reasons for the patterns we see. But it is obvious that some patterns can create confusion and misjugdgment, but if the bold stripes and zig-zag patterns are due to motion dazzle or not, is hard to tell.

The pictures below show examples of animals with bold or high contrast patterns:

Picture from <http://www.youtube.com/watch?v=cgdVVU8tBTQ>, viewed 8 April 2014.

Picture from <http://www.nytimes.com/2008/08/19/science/19obdazz.html?partner=rssnyt&emc=rss&_r=0>, viewed 8 April 2014  

Picture from <http://news.asiantown.net/r/33698/why-do-zebras-have-stripes-distinctive-markings-create-an-optical-illusion-that-dazzles-predators-and-masks-movement > viewed 8 April 2014

Biography:

Stevens, M, Yule, DH, Ruxton, GD 2008, 'Dazzle coloration and prey movement', Proceedings of the Royal Society: Biological science,vol. 275, no. 1651, pp 2639 – 2643, viewed 8 April 2014, <http://rspb.royalsocietypublishing.org/content/275/1651/2639.full >

Caro, T, Izzo, A, Reiner, AC, Walker, H, Stankowich, T 2014, 'The function of zebra stripes', Nature communications, vol. 5, no. 3535, viewed 8 April 2014 <http://www.nature.com/ncomms/2014/140401/ncomms4535/full/ncomms4535.html>