“Why do zebra have stripes?”
This is certainly a topic that has been covered numerous times, not only on the Londolozi blog but by most guests that come on safari here too. So, why revisit it? Well, with new research comes new information and with that comes different opinions or some scientific evidence to back up previous theories. James Tyrrell did open the table to this topic: “any thoughts on the matter?”
The Plain’s Zebra spend the large majority of their time in the open savannah.
Many theories have been suggested from camouflage, confusion tactics, to deterring flies but the theory that has the most scientific backup is thermoregulation. Animals have evolved (and continue to do so) for millennia and the underlying reason for this is to better cope with the environment that they live in. Zebras are grazers, meaning they feed on grass, and therefore they favour open savannah as opposed to thicker woodier areas. Open savannah goes hand-in-hand with less shade and more exposure to the blistering African heat.
It’s hard to deny the ability to identify a single zebra as it blends into the herd of stripes
Now I’m not saying that zebras are not plagued by biting flies and that there may be evolutionary changes to cope with this, perhaps the involuntary twitching of their skin has evolved millennia ago for this very reason. What I’m saying is that surely the most important aspect for an animal spending the majority of their time in the sun is to ensure that they do not overheat.
An amateur naturalist, Alison Cobb, spent many years with her husband, zoologist Stephen Cobb, living in sub-Saharan Africa and devoted a significant amount of time to researching zebras. Stephen had a student that worked with zebras who reported the ability to calm them down by brushing them with a long-handled broom. This prompted Alison to ask for permission to try and tame a zebra at the Animal Orphanage in Nairobi, which would aid her in collecting research data. She attempted to brush the zebra daily in the hopes the zebra would become accustomed to her and comfortable with her presence. What Alison realized, apart from the fact that the zebra enjoyed the brushing, was that the zebra was able to erect the black stripes of her coat. Through previous research she had already determined that the black stripes of the zebra would, on any given day, heat up to between 12 – 15 degrees Celsius higher in comparison to the white stripes. Whereas a lifeless zebra hide draped over a clothes horse would increase to more than 16 degrees Celsius. So what function was the raised hair playing?
Zebra are part of the Equidae family of which a characteristic is the ability to sweat. Think of a racehorse galloping down the home stretch covered in sweat. The sweat, however, is different from humans’ sweat; it’s frothy. Equines produce a protein called latherin enabling the production of this frothy sweat. The raised black hair allows this sweat to be spread all the way to the tips of the hair. This increases the surface area and lowers the surface tension so that evaporation is more effective over the black stripes of their coat in the heat of the day.
Furthermore, the temperature gradient between the black and white stripes creates small-scale convection air currents just above the skin. This, in my opinion, is a twofold adaptation. Firstly, with increased airflow over the sweat, evaporation is increased. Secondly, which backs up the fly deterrent theory, is that flies find it more difficult to land on an animal with stripes but not due to their inability to spot a landing on a striped surface but rather due to the mildly turbulent air just above the skin of the zebra.
A zebra foal just big enough to rest on the back of her mother as the stallion of the harem watches in the other direction.
To dismiss any of the previously mentioned theories would be futile but why should we write off the fact that zebras have evolved to adapt for all of these different reasons? The fact that we can still go out on game drive and sit and discuss the different reasons for animals having the adaptations they do is what keeps me, and I’m sure many of you, coming back time and time again.
Zebra are known for their tough migration and sophisticated interactions. In addition they are so beautiful! Thank you for updating with deep information on them. The foal is too cute… all pictures are lovely
Oh, love this. It sounds very plausible, esp when the black hairs are raised and the white ones are not. Interesting!!
An exciting theory. Why not?
Dear Barry, great article on zebras with really interesting theories regarding their stripes. Thanks!
That is a great deal of interesting information. I wonder what new theories will arrive in the future!! Thank you! Victoria
Hi Barry. Thank you very much for the interesting facts about the colour and cooling effect of how the Lord made them. HOWEVER, you still have to answer the age old question of whether Zebras are black with white stripes – or white with black stripes! Comments would be appreciated! Neil and Wendy M
Hi Neil & Wendy, interestingly enough if you had to shave a zebra you would find that their skin is actually black. As the embryo is developing in the uterus it is actually black. Later on the white stripes start to emerge as the gene code for the dark pigment melanin is selectively deactivated for specific hair follicles. This is also why each zebra has its own unique pattern. Fascinating stuff in my opinion.
I have learnt something now Barry from your very interesting story on the Zebra stripes. Never could I imagine that the black hairs could raise up and allow the sweat to go to the tips for evaporation. I am sure these beautiful Zebra are getting hot in this African sun of ours, and that is a way to cool themselves down. So glad that you wonderful Rangers speculate about these theories and talk about them between yourselves and tell us about it. Shame I am sure those horrible flies do also bite them and irritate them. Thanks Barry for your intelligent answers to the matter of the Stripes.
Thanks Barry for another interesting/informative article addressing a “why does” question pertaining to an African plains animal. There are so many professional and non-professional theories bantered about, that one doesn’t know what to believe, so zebras’ stripes will be debated forever-until there’s scientific proof. Until then, I like to think a dazzle of zebra is a group that is unique and beautiful, whatever the reason for their stripes.
This is fascinating and makes a great deal of sense. Thank you for the edification! The photography is lovely, especially the zebra’s back photo.
very interesting article, thank you.
There are not too many things that compare to the strips of a zebra! I find them absolutely stunning! You photos are wonderful… and your theory… as long as Zebras walk the plains, we will ponder over such an amazing creature…I truly just love looking at how beautiful they are! Thank you for the share!
Barry, Thanks for the educational post on Zebras! We so appreciate when we get to learn about the wildlife we see at Londolozi! Really interesting information – wow!
Stunning photos!
Interesting theories and beautiful photos – thank you.
Fascinating Barry, adaptation to ones environment has allowed for survival for most if not all species.
I love these thought prevoking topics you all bring up from time to time. Such a fascinating read Barry and as always have learnt a thing or two about these beautiful animals. Super interesting that the foetus is jet black and that the strips form at a later stage during gestation. Perhaps it’s lucky for them that it is not the other way around, much like the Dalmatian who’s generally white at birth and it’s ‘ticking’ or spots develop after a few weeks. Zebra would have a few hot and very exposed days to be preyed upon and the possible added defect of being deaf !