Is it true that strips need zebram for disguise?

Many people think that the striped color of the zebr helps them to disguise themselves and thus defend themselves from predators. We checked whether this is really so.

Scientists from the University of Kalgary (Canada) and the University of California in Davis also wondered whether Zebram really needed strips to hide from predators. They spent study, during which various filters were superimposed on the digital images of the zebr to imitate the vision of predators. In addition, having estimated the width and contrast of the bands, scientists calculated the maximum distance at which lions, tigers or hyenas can see the color of the zebra. It turned out that predators do not distinguish between stripes at a distance of more than 50 m in the afternoon, 30 m at dusk and 9 m in hoarse nights. They see some outlines, but not color, so the disguise at that time is meaningless. With a lower distance, when the strips are already distinguishable and could help Zebram in this way hide, predators can already hear and smell their victim, so the disguise will not help. Scientists came to the conclusion that in forest massifs, the striped color of animals could still serve them with a disguise, but the zebras live mainly in the savannahs, in open spaces, where their stripes simply have nothing to merge with.

Version The fact that such a color creates an optical flickering effect of a strobe, knocking down predators that some scientists expressed, zoologists from Calgary and California also refuted. Their experiments Showedthat the eye of a predator may well distinguish the outline of the zebra in an open area no worse than an animal plain color. In addition, at the time of danger, zebras prefer to run, and not hide, which, according to scientists, also discredits the version with stripes as camouflage.

Tim Karo, a biologist from the University of California in Davis, one of those who conducted experiments with filters that imitate the vision of predators, I spent More than 20 years to find out why zebra is needed strips. He analyzed every hypothesis and issued Monograph, where he described in detail his many experiments and proved the failure of the majority of existing theories. In addition to camouflage, the most likely and common versions of why zebram strips are two: thermoregulation and protection against insects.

Some scientists They believethat the strips help Zebram to escape from overheating, providing thermoregulation. They conducted a study and found out that the “striped” zebr is more intense where the habitat is the most hot (or with the most intense sun). Biologists Alison and Stephen Cobb, also supporters of theory of thermoregulation, discoveredthat the temperature of the black stripes on the body of the zebra in the hottest time of the day is 12-15 ° C higher than the white. At the same time, animals can raise or reduce their heated wool, thus providing themselves with either cooling in the afternoon, or maintaining heat in the early morning. 

However, experiment Hungarian scientists refutes this theory. They installed barrels of water in the sun and covered them with artificial and natural zebras skins, as well as white and gray skins. It turned out that the latter cool the water much better and protect against overheating. According to scientists, this proves that the strips could not have arisen in the zebra for thermoregulation, since this is not justified from the evolutionary point of view. 

Another version, the most likely today, is the strips help zebram to defend against insect bites. In 2014, Tim Karo and his colleagues collected and systematized data on the dependence of the degree of “stripes” of zebras and external environmental conditions. It turned outthat there are more stripes and they are more contrasting where there are more parasite insects. After that, Karo with a group of scientists moved to experiments: They watched zebra and horses. At the same time, the scientists threw striped “raincoats” to some horses to disguise them under the zebr, and the blinds were less likely to sit on striped surfaces. Apparently, the strips were confused by insects and they could not find a place for landing, but scientists have yet to find out the true reason for their behavior.

This version was confirmed and experience Japanese colleagues Karo. They applied several cows on the skin of several cows and began to observe. As a result, those cows whose skins were striped were bitten two times less than the rest. 

Thus, it is not yet known for which Zebram needs strips and why they appeared during evolution. Scientists reply that even the main hypotheses can be divided into at least 18 separate versions and so far there is no unequivocal answer to this question. But existing studies allow us to argue that the strips do not provide zebram for masking from predators and at the same time help to confuse insects and protect themselves from their bites.

Most likely not true

What do our verdicts mean?

Read on the topic:

1. Tim Karo. Strips of zebra
2. Is it true that the chameleon changes color for masking?
3. Is it true that the flight of a bumblebee contradicts the laws of physics?