Tell No Tales: Why Horses Swish Their Tails So Rapidly

by | 10.22.2018 | 8:13am

Most people think the purpose of a horse's tail is to keep bugs at bay — but it took a recent study from a mechanical engineer to understand how. David Hu, associate professor at Georgia Institute of Technology and graduate student Marguerite Matherne investigated the role of a horse's tail to determine if horses use them for more than simply insect deterrents. Matherne examined the tails of 12 mammals, including giraffes, elephants and zebras, as well as horses.

The tail is a pendulum and as such, it should swing at a rate that is dependent on the length of the pendulum; however, horses swing their tails three times faster than expected, expending significantly more energy.

To investigate what the horse's tail actually does, Matherne bought a horse hair whip and used 100 mosquitoes to see if she could keep the biting insects at bay with the whip. She could not—the movement of the air as it approached the mosquitoes blew them away from the whip because they are so light.

Matherne then created a tail simulator to measure how tails deterred mosquitoes. This tail replication was able to repel up to 50 percent of the mosquitoes.

The researchers determined this was the reason for the energy expenditure — horses moved their tails so rapidly to generate enough wind to be comparable to the speeds kept by a flying mosquito, about 2 mph. This helped keep the insects at bay.

Read more at Scientific American.


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