Wet Dog Shake VIDEO Reveals Physics Behind Furry Mammals' Shakedown Technique

Dogs may look silly when they shake themselves down after a dunk in the water, but there's some serious physics behind their antics.

A video (above) from Nature's YouTube channel shows several animals giving themselves a shakedown in super slow-motion, and demonstrates how the speed of the shimmy decreases as the animals get bigger.

It's not just dogs that shake themselves dry. In addition to the canine, the video features several different species shaking water off their fur, from a rat to a lion to even a kangaroo.

And some creatures are better at it than others -- for instance, a large dog can shed 70 percent of the water in its fur in four seconds, Nature notes, and the creature's loose skin helps it spin the water off itself more efficiently.

The video was inspired by a 2012 study that showed the relationship between an animal's size and the speed of its shake. The study's authors, from the mechanical engineering and biology departments at Georgia Tech, looked at 16 different species ranging in size from a mouse to a bear.

Indeed, an animal's size can be used to predict how fast it will shake. This is because water sticks to fur with a so-called "capillary force," and smaller animals need to spin faster to generate enough centrifugal force to overcome the stickiness and shed the water.

So why have these animals evolved to shake it? Being wet makes outsize demands on a land animal's body.

The study's authors write, "A wet 60-pound dog, with one pound of water in its fur, would use 20 per cent of its daily caloric intake simply to air-dry. It is thus a matter of survival that terrestrial animals remain dry in cold weather."



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