- Zebras’ distinctive stripes help deter insect landings.
- Zebra stripes may create an optical illusion for predators.
- The black and white coat assists in thermoregulation.
Stubborn and proud, the zebra is a wild equid native to Africa. Impossible to confuse with any other mammal, it stands out with its unmistakable black and white striped coat. Often considered curious, its two-tone pattern has long intrigued scientists, and it continues to do so. What evolutionary advantage might be hidden behind such a distinctive coat pattern?
To our eyes, it seems like the zebra wants to attract all the attention rather than blend into the landscape, as most herbivores do. However, don’t let appearances deceive you; just like in the African savanna, not everything in life is black or white. While the function of stripes is still debated in the scientific community, research is now focused on three possible explanations: thermoregulation, protection against insect bites, and evasion from predation.
While most zebra species are known for their distinctive stripes, not all have the same stripe patterns. Different species, such as plains zebras and Grevy’s zebras, have variations in stripe density and pattern.
Escaping Predators
Firstly, strange as it may seem, the stripe pattern is thought to influence the perception of predators. We’re not talking about camouflage as such, but rather the creation of an optical illusion.
According to studies, the majority of predators can see stripes at a distance of almost 50 meters (about 164 feet) during the day, but only at less than 30 meters (about 29 feet) at night—the best time for hunting. On moonless nights, a predator can only distinguish the zebra pattern if it is within nine meters of the animal—close enough for the prey to hear or smell it. Beyond this distance, the target appears rather gray and blends in better with its surroundings, which is convenient considering that a lion, for example, cannot distinguish colors and perceives its world in shades of gray.
Another idea is that, when fleeing, the intermingling stripes of the galloping herd make it more difficult for the predator to focus on a single individual. Failing to isolate his prey, the assailant, who only has a few seconds to make contact, would give up the chase. This theory, however, is more difficult to confirm scientifically and is not universally accepted by biologists.
Zebras’ black and white stripes create optical illusions that disrupt the outlines of their bodies, making it challenging for predators to distinguish one zebra from another. This visual confusion helps zebras evade predators like lions and hyenas.
Repelling Insects
One of the most widely supported hypotheses is that black and white stripes act as a natural insect repellent. In Africa, these unwelcome swarms can transmit, among other things, sleeping sickness, African horse sickness, and potentially fatal equine influenza.
Studies have shown that flies and horseflies are much less likely to land on striped coats compared to solid-colored ones. If the same number of insects hovers around animals with plain or striped coats, the pests seem to have difficulty perceiving the stripes as a suitable landing site; they tend to bounce off the coat.
Placed under the same conditions, zebras are therefore significantly less bothered by mosquitoes than their domestic cousin, the horse.
Regulating the Body Temperature
Other researchers are convinced that the primary evolutionary advantage of the zebra’s black and white coat is thermoregulation. The idea behind this hypothesis is that the black and white stripes heat up differently under the sun, causing microturbulence near the coat.
These air movements on the zebra’s skin’s surface would be sufficient to lower its body temperature, a clear advantage when grazing in open terrain under a scorching sun.
It is observed that the stripes of species living in the north, subjected to higher temperatures, are generally better defined on the coat than those of individuals living in the cooler southern regions.
One thing the scientific community agrees on, however, is that Mother Nature never does anything without reason. Far from being an arbitrary whim, the zebra’s beautiful stripes likely hide many more advantages that will continue to engage biologists in the years to come.
