Theory behind Zebra stripesDate: 21 August 2020 Tags: Miscellaneous
Research into the issue of zebra stripes has intrigued scientists since long time. A new study looks extensively into one possible reason why a zebra has stripes — that these help confuse blood-sucking parasites.
These researchers did find evidence to back up this theory. But that was in a previous study, published in 2019. Then, they showed experimentally how flies got confused by zebra stripes.
Researchers investigated the behaviours of horse-flies around captive zebras and domestic horses, using video analysis techniques.
From a distance, horse-flies circled both zebras and domestic horses at the same rate. However, when they approached a zebra, the horse-flies failed to slow down.
Slowing down is essential for a successful landing. On horses, successful landings were found to be more frequent. But when approaching zebras, the horse-flies either flew over the stripes, or bumped into them. The takeaway: it is most likely the stripes that are confusing the horse-flies.
The idea is that the stripes induce an optical illusion that confuses the visual system of the fly, convincing them that the striped object is not an object at all, so the fly carries on past without landing.
One idea is that the stripes provide the zebra with camouflage from predators by creating a kind of optical illusion.
The stripes on a zebra blends with the lines of the tall grass around it. This might not work for a human observer, for the black and white stripes would stand out against the coloured grass.
But the zebra’s main predator, the lion, is colour-blind: Proponents of the camouflage hypothesis note that a lion would not be able to differentiate between zebra stripes and lines of grass.
By this theory, the stripes help a zebra keep cool in the heat. Researchers have found that the temperature of the black stripes is considerably warmer than that of the white stripes.
These temperature differences cause air flows between the black and white stripes, which could help cool the zebras by speeding up the evaporation of sweat.
It is known that every individual zebra has a unique pattern of stripes, just like every human has a unique set of fingerprints. This hypothesis goes that the unique stripes help individual zebras recognise one another.