The striped pattern of zebras has the effect of avoiding blood-sucking horseflies

Zebras are characterized by black and white striped patterns, but the clear reason why they acquired striped patterns in the process of evolution has not been clarified. A study conducted by a research team at the University of Bristol in the United Kingdom found that zebra patterns are useful for 'repelling horses'.

Why don't horseflies land on zebras? | Journal of Experimental Biology | The Company of Biologists

Experts have discovered how zebra stripes work | University of Bristol

The exact reason why zebras have striped patterns has not been clarified, and various theories have been proposed so far, such as ``to hide from predators'' and ``to improve the efficiency of body temperature regulation.'' Meanwhile, in 2019, a research team at the University of Bristol conducted an experiment to `` put a striped coat on a horse without a striped pattern '', revealing that the striped pattern has the effect of avoiding horseflies.

Why are zebras striped? The reason is finally being elucidated - GIGAZINE

by Magda Ehlers

As mentioned above, it is clear that the striped pattern has the effect of repelling horseflies, but ``the reason why horseflies avoid the striped pattern'' is not clear. Hypotheses such as 'Aphid is causing an optical illusion' and 'Aphid gathers at 'a place where light that passes through a polarizing filter is reflected'' were established. In order to verify these hypotheses, the research team conducted an experiment of ``putting a coat on a horse with a variety of patterns, including striped patterns, and counting the number of times Abu perches on the body in a certain period of time.''

The specific experimental procedure is as follows. First, six types of patterns were drawn: 'plaid pattern', 'pattern with randomly arranged black and white squares', 'pattern with black triangles', 'pattern with white triangles', 'monochromatic gray', and 'bark pattern'. We prepared coats for horses and investigated 'the number of times horseflies landed in a certain period of time' when wearing each coat.

As a result of the experiment, the 'monochromatic gray' coat attracts the most horseflies, and if you wear a coat with a 'pattern with black triangles' or a 'pattern with white triangles', you should wear a 'monochrome' coat. It became clear that horseflies land less often than when In addition, it was confirmed that the 'plaid pattern' and 'the pattern of randomly arranged black and white squares' have a higher effect of repelling bugs than the pattern of lined up triangles.

From the results of the experiment, the research team concludes that ``patterns with strong black and white contrast, such as striped patterns and checkered patterns'' have the effect of avoiding horseflies.

On the other hand, there was no significant difference between the ``checkered pattern'', which is prone to optical illusions, and the ``randomly arranged pattern of black and white squares,'' which is unlikely to occur. The theory that there is, was denied. Furthermore, as a result of photographing 'a pattern with black triangles' and 'a pattern with white triangles' through a polarizing filter, it was found that the white part reflects light well. For this reason, the theory that ``Aphid gathers in the place where the light that passes through the polarizing filter is reflected'' is also denied.

In the future, we will continue to study the reason why the striped pattern did not develop in animals other than zebras.

in Science,   Creature, Posted by log1o_hf