Picky eater.

Sluuurp! With a stretch of its tongue, this cow takes a lick of the inside of its nose.

What's the reason for this wet wipe? Tiny glands within the nose secrete mucus, making the nostrils moist and sticky. When a cow inhales, bacteria from the air get caught in the gummy mucus. That helps to keep harmful bacteria from reaching a cow's lungs, where they could make the animal sick.

But all of this mucus can make for a messy nose. When a cow's nose gets runny, instead of grabbing a tissue, it uses its superlong, triangular-tipped tongue to poke into its nostrils and clean out the bacteria-laden mucus. "The shape of the tip of their tongue is just perfect for licking their nose," says Gillian Perkins, a large animal doctor at the College of Veterinary Medicine at Cornell University in New York.

Making for an even better scrub brush: Bumps cover the tip of a cow's tongue. Similar to the tiny bumps on your own tongue, a cow's papillae are extra large and rough. This helps the animal scrape its nostrils clean.

After washing the insides of its nose, the cow pulls its tongue back into its mouth and swallows the microbe-packed mucus. The cow's digestive system breaks down the mucus, destroying any bacteria that are caught in it. But if a cow's nose harbors too many harmful microbes, the animal cannot keep up with the nose swabbing and may become sick, says Perkins. Then, a trip to a veterinarian is in order.