Zebra stripes are a no-fly zone for midges.

In our modern age of rapid development of IT-technologies, it seems that we already know everything and there is not a single mystery left in the world. Why the wind blows, why the bun is round, even why the aborigines ate Cook - known to almost everyone.

But why zebras are striped , probably not many people guess. Nevertheless, it is ALREADY found out ...

Below is a translation of the article that scientific testing has shown the advantages of a striped zebra coat.

Zebras are famous for their contrasting black and white stripes - but until recently no one knew why they wear their unusual striped pattern. This issue was discussed 150 years ago by great Victorian biologists, such as Charles Darwin and Alfred Russell Wallace.

Since then, many ideas have been put forward, but only in the last few years have serious attempts been made to test them. Existing ideas can be divided into four main categories:

• zebras are striped to avoid predation;
• zebras are striped for social reasons;
• zebras are striped to keep cool;
• stripes help them avoid mosquito bites.

And only the last of them has passed the test. And our latest research will help fill in the gaps in your knowledge with a large number of details about why.

Fig_1. Camouflage? Identification? Natural conditioner? No, no and NO.

What is the use of zebra stripes?

Can the stripes help the zebra not become a predator's food? There are many problems with this idea. Field studies show that zebras, even in low light, are easily distinguished by the human eye. When they are among the trees or pastures, they look far from disguised . And escaping from danger, zebras do not behave in such a way as to increase confusion, possibly caused by stripes, which makes hypothetical ideas about stunned predators untenable .

Worse, the sight of lions and spotted hyenas is much weaker than ours. These predators can only distinguish stripes when the zebras are very close, at a distance, when they can probably hear and smell the prey. Thus, the bands are unlikely to be useful for protection against predators .

Most of all, this idea is undermined by the fact that zebras are the preferred prey for lions - in a study after a survey of all of Africa it turned out that lions kill them more than one would expect from their numerical abundance. Thus, the stripes cannot serve as a very effective defense against the predators of this important carnivore. Here you have a hypothesis about evading predators.

What about the idea that stripes help zebras interact with members of their own species? Each zebra has a unique strip pattern. Could this be useful for individual recognition? This possibility seems unlikely, given that evenly stained domestic horses can recognize other individuals in appearance and sound . Striped members of the horse family do not care for each other , as a form of social connection, more than bezpolosye types of horses. Moreover, very rare bezpolosye representatives of zebras do not shy away from members of their group , and they successfully multiply.

How about protection from the hot African sun? Since black bands can be expected to absorb radiation and whites reflect it, one idea was that the bands create convective currents along the back of the animal, cooling it.

Pic_2. Field experiments checked how different colors affect the temperature of barrels filled with water.

Again, what seems unbelievable: careful experiments in which large water barrels were draped in striped or uniform colored skins, or dyed in stripes or continuously, showed no difference in the temperature of the internal water . In addition, thermographic measurements of zebras, impalas, buffaloes, and giraffes in the wild show that zebras are no colder than other species with which they live.

The last idea about strips sounds ridiculous at first sight - the strips stop bloodsucking insects from getting blood - but it has a lot of support.

Early experiments of the 1980s showed that tsetse flies and horseflies shied away from landing on striped surfaces , and were only recently confirmed .

The most convincing, however, are the data for the entire geographical area of ​​the seven existing animal species. Some of these species are striped (zebras), some are not (Asian donkeys), and some are partially striped (African wild ass). For different species and their subspecies, the intensity of alternation of bands is closely related to mosquito bites in Africa and Asia. Thus, wild animals living in areas where midges' irritation continues throughout the year are more likely to have noticeable striped patterns.

Fig_3. Map A on the left shows where living animals are striped or smoothly colored. Map B on the right highlights in blue the distribution of tsetse flies (Glossina) and areas where a horse fly bites (Tabanus) annually for seven months in a row.

We believe that the reason animals should be striped in Africa is because the African midge carries diseases such as trypanosomiasis, African horse sickness and horse flu, which can be fatal to animals. And zebras are particularly susceptible to attempts at midges bites into the oral cavity because of their short, tied hair. Having a fur pattern that will help avoid mosquitoes and the deadly diseases they carry would be a strong advantage, meaning that the stripes will be passed on to future generations.

Checking the idea that strips and flies do not fit

But how do lanes actually affect midges? We went to explore it at the stable in Somerset, UK, where they gather horseflies in the summer.

We are lucky to work with Terry Hill, the owner of the stable. We were able to get very close to his horses and tame lowland zebras, which allowed us to actually watch the midges landing or flying past the horses. We also videotaped the behavior of midges around the horses and put on colorful capes on them.

Fig_4. Evenly painted horses received far more landings and landings from annoying midges than zebras.

It is important to remember that flies have much worse eyesight than humans. We found that zebras and horses received the same number of approaches from gadflies, probably attracted by their smell, but zebras experienced far fewer landings. Around the horses, flies soar, curl and turn before landing again and again. On the contrary, flies near the zebras either flew past them, or made a single quick landing and flew away again.

Frame-by-frame analysis of our videos showed that flies smoothly slow down when they approach brown or black horses before they make a controlled landing. But they did not slow down when they approached the zebras. Instead, they flew past or literally bumped into an animal and bounced off.

Pic_5. Striped capes on monophonic horses reduced the number of flies raids on covered parts of the body.

When we put black or white capes or striped capes on the same horse to control any differences in animal behavior or smell, again the flies did not land on the stripes. But there was no difference in the speed of landing on the bare head of a horse, showing that the lanes exert their effect close, but do not prevent them from flying at a distance.

And it showed us that the striped capes, which are currently sold by two companies, really work.

So now, when we know that the stripes affect the gadfly very closely, and not at a distance, what is actually happening in inches from the host? One idea is that the stripes create an optical illusion that violates the expected pattern of movement of the fly when it approaches the zebra, preventing it from landing properly. Another idea is that flies see a zebra not as a solid, but as a series of thin black objects. Only when they are very close, do they realize that they are going to strike a solid body and deviate instead. Now we are considering these opportunities.

Thus, our fundamental study of the behavior of flies not only tells us why zebras are so beautifully striped, but also has real implications for the equestrian industry, with the potential to make riding and keeping a horse less painful for a horse and rider.