Watch: Cleanliness-Freak Gorilla Walks Like Human To Keep His Hands Clean

An 18-year-old gorilla named Louis was captured on video walking about his zoo enclosure upright like a human, supposedly because he hates to get his hands dirty.

The 500-pound, six-foot tall gorilla, who lives at the Philadelphia Zoo, is seen in the video walking upright while carrying tomatoes and other snacks with his hands.

"Although gorillas occasionally walk on two legs (bipedal), it is less common," the Philadelphia Zoo said in a post on Facebook. "Not for Louis though — he can often be seen walking bipedally when his hands are full of snacks or when the ground is muddy (so he doesn’t get his hands dirty)!"

The male western lowland gorilla is reportedly said to do this in order to keep his hands clean, even while he crosses a tight-rope over a mud puddle in his enclosure to avoid getting dirty, zoo officials said.

The zoo first posted the footage of Louis' walking two weeks ago, but it took off on social media on Monday when CBS reposted it to Twitter. The video has gone viral since and shows the gorilla at Philadelphia Zoo upright on two legs, rather than the typical knuckle-to ground stance. It had garnered over 280,000 views at the time of publishing this story.

In the wild, western lowland gorillas have been observed sometimes walking upright in order to reach food or wade into swamps.

Louis is "fully healthy, 470 lbs. of solid muscle" and his "hands and feet and legs work very well," Michael Stern, curator of primates and small mammals at the Philadelphia Zoo said.

Stern stated Louis was simply exhibiting behavior that, although "pretty rare," does manifest occasionally among gorillas.

"They will walk upright when they're playing with each other or they're displaying to try to look big and strong . . . or to wade into a swamp," Stern told the Washington Post.

Born in May 1999 at Missouri's St Louis Zoo, Louis moved to Philadelphia in 2004. The 18-year-old primate is said to be one of two bachelor gorillas present at the zoo.

While the upright stance in gorillas is pretty rare, the difference is that other gorillas might walk upright "for a few seconds or a few steps," this 18-year-old can stroll around on his hind legs for an extended period and, in fact, seems to prefer to, especially during urgent times when it comes to protecting his snacks.

"He actually does it more often than you might think," Stern said. "It depends on the situation. If the ground is really muddy, he will do it more often. If he's getting fed some treats, like tomatoes, that might squish more, then he tends to walk upright with things like that."