WHY DO ZEBRAS REALLY HAVE STRIPES? IT’S NOT PROTECTION AGAINST LIONS, BUT FROM BITING FLIES!
So this is another one of those interesting surprises for me. I distinctly remember as a kid learning in no uncertain terms why it is that zebras have stripes. It was one of those explanations about evolution and the variety of wildlife in Africa documentaries. And the reason was, it makes it harder for predators like lions to see them. And, well, that seemed to make a lot of sense at the time. But I heard that over the years again and again. But it’s totally, absolutely wrong! Lions can’t even perceive the stripes until they’re almost on top of zebras! So what is the most likely reason now? Well, biting flies. Stripes on zebras helps keep the biting flies away.
BIOLOGIST OBSERVED ZEBRAS AND HORSES TOGETHER IN ENGLAND TO SEE BITING FLIES IN ACTON
Tim Caro is a biologist at UC Davis and has been pondering the zebras and stripes mystery for a long time. He’s even written a book about it. So he and some colleagues went to Hill Livery, a stable in southwest England that hosts several zebras as well as regular old horses. While there, Caro watched in person and filmed the animals to compare how biting flies approached them. And he they saw gives the theory a strong foundation. The flies had no problem approaching both horses and zebras. But the stripes make it a lot harder for flies to land on zebras. How much harder? To the tune of 75% less flies landing on zebras than on horses.
ZEBRAS HAVE REALLY SORT HAIR, MAKING THEM VULNERABLE TO BITING FLIES AND DISEASES
Those numbers are hard to dismiss as random. But why do zebras need an evolutionary defense against biting flies? Well, several reasons. Zebra hair is really short compared to horses. So these painful biting blood suckers, if they can land, have a really easy time locating blood vessels to bite into. And the other reasons they need this defense? Diseases. They are really vulnerable to getting trypanosomiasis, African horse sickness, and equine influenza. All of them can be fatal. And all of them are spread by biting flies looking to score some equine blood. So Caro and his team put striped horse coats on the horses to see if that would deter the biting flies as well. And it did!
While Caro and his team aren’t ready to make recommendations to the horse industry worldwide just yet without more testing, they seem ready to recommend striped shirts for people!