If a patient shakes, let it. That shaking may be as good as a bath. At least, that’s what a recent study suggests.

Researchers from the Georgia Institute of Technology (Georgia Tech) recently combed through more than 24 studies and did surface measurements for 27 mammals and insects and identified both renewable and non-renewable ways animals clean themselves.

Their findings were published online on Oct. 21 in the Journal of Experimental Biology.

The research team focused on the many ways hair allows animals to both get dirty and remain dirt-free. The researchers ran calculations to find the true surface area of animals, or the surface area that includes every location where dirt can be collected. The hairier it is, the larger the creature’s true surface area. In fact, the team says it’s 100 times greater than its skin surface area.

“Animals likely evolved with hair in order to stay warm. But it also brings a burden,” said David L. Hu, PhD, a Georgia Tech associate professor who co-led the study. “More hair means more surface area that can trap dirt, dust and pollen.”

With all that surface area comes the challenge of keeping away all the dirt. It turns out that animals use a variety of ways to stay clean. Some depend on non-renewable strategies and use their own energy.

“Dogs shake water off their backs, just like a washing machine,” said Guillermo J. Amador, PhD, who co-authored the study. “Bees use bristled appendages to brush pollen off their eyes and bodies. Fruit flies use hairs on their head and thorax to catapult dust off of them at accelerations of up to 500 times Earth’s gravity.”

Other animals and insects use more efficient, renewable cleaning tactics. Eyelashes, for example, protect mammals by minimizing airflow and funneling particles away from eyes.

Photo credit: © iStock/massimo colombo