The Science Behind The Shake: Why Mammals Shake Themselves Dry
NEW YORK (CBSNewYork) – If you’re a dog owner, you know firsthand what happens when your dog gets wet – it does a shake, spraying water everywhere.
While most of us try to avoid getting showered by the dog shake, researchers at Georgia Tech decided to study it and discovered animals actually do a miraculous job of drying themselves.
They used a high-speed camera to record the shakes, resulting in images so stirring that the video was uploaded to YouTube’s Nature Channel.
The study found the smaller the animal, the faster is shakes. For example, a mouse shakes 27 times per second while a pig had about eight shakes per second.
Dogs shake about four times a second, leaving them 70 percent dry within one to four seconds, the study found. A dog’s loose skin increases the speed at which the water is whipped away while the dog’s backbone goes back and forth only 30 degrees.
“The skin will go back and forth 90 degrees to the right and then 90 left,” said one of the study’s researchers Dr. David Hu. “That’s only possible because it’s loose enough to perform this whipping action around the body.”
The researchers even went to the zoo and recorded a lion, as well as goats, sheep and other animals. Hu said furry mammals probably developed the shaking mechanism to avoid staying wet and getting hypothermia.
The Georgia Tech team even managed to x-ray a rat shaking.
But the one animal that can’t seem to get the hang of it is the kangaroo. They’re built for hopping, not shaking.
“It can’t really shake,” Hu said. “It has this sort of large buttocks, these kangaroo buttocks and it can’t really shake that around so it just shakes its head.”
Not a crisis for kangaroos, researchers say, because they live mostly in hot climates which means they dry quickly in the heat.
Scientists hope studying how animals shake will help them create man-made equipment for fast drying technology using similar techniques.
Researchers also built a robotic wet-dog-shake simulator to study how drops were ejected from the body.
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