Wednesday, May 23, 2012

How The Zebra Got Its Stripes?

The explanation I saw from documentaries stated that zebra evolved its stripes to confuse the lion.

Lions are color blind, so a group of rampaging zebras can be extremely confusing and headache-inducing.

But Gabor Horvath and colleagues from Hungary and Sweden have come up with another explanation: zebra's stripes ward off blood-sucking parasites.
Like us, animals hate parasites too, and one parasite, the female horseflies (tanabids) can deliver one hell of a bite. Like female mosquitoes, they feed on mammal blood for reproduction, and they carry diseases too.
They lay their eggs on stones or vegetation close to water, guided by the horizontally polarized light reflected from the water surface. And these evil vampires are also guided to their meals via horizontally polarized light reflected from animal skin.
To test this, the team traveled to a horsefly-infested farm in Budapest and set up three horse model; a white, a dark, and a striped model. Interestingly, the striped model was the least attractive to horseflies. The team also varied the width, density, and angle of the stripes, and found out that narrower stripes attracted fewer tanabids.

The team pointed out that developing zebra embryos start out with a dark skin, only to develop white stripes afterwards. It's possible that evolution has favored the development of zebra stripes to confuse color-blind predators, as well as ward off blood-thirsty vampires.

Should we do the same to ward off mosquitoes?

Polarotactic tabanids find striped patterns with brightness and/or polarization modulation least attractive: an advantage of zebra stripes, Ádám Egri et. al, J Exp Biol 215,  March 1, 2012  736-745. 

No comments:

Post a Comment


Related Posts Plugin for WordPress, Blogger...