Louis the lowland western gorilla (Photo Credit: Philadelphia Zoo)

While gorillas are perfectly capable of walking on two legs, most take just a step or two before dropping on all fours. However, Louis, a 16-year-old male gorilla at the Philadelphia Zoo, is often seen taking longer strolls, especially when the ground is wet or he is holding a delicious snack or two.

According to a 2015 blog by the great ape’s keeper, “When caught out in a rainstorm, he'll run bipedally across the yard to seek cover, and when he accidentally steps in mud, he'll find a leaf or a paper bag and wipe his hand or foot off until they are clean again.” To help Louis in his desire to keep his hands clean, the zoo has created a bridge using fire hoses which allows the gorilla to avoid muddy puddles in his enclosure.

Louis the gorilla likes to walk on his two feet when given snacks (Photo Credit Philadelphia Zoo)

The six-foot-tall, 450-pound animal is among the largest and, according to officials, “probably the shyest” of all the zoo’s gorillas. Born in St. Louis, the western lowland gorilla has spent his entire life in captivity. Michael Stern, the zoo’s curator of primates and small mammals, believes his bipedal personality quirk is probably a result of spending his whole life around bipedal humans.

Endemic to the lowland swamps of Central Africa, the western lowland gorilla is the smallest of the four gorilla subspecies, which include the cross river gorilla, the mountain gorilla, and eastern lowland gorilla. Easily recognizable by their brownish coloration and streak of silver hair across the small of their backs and, in some cases, rump and thighs, the great apes are a critically endangered species, thanks to a drastic decline in population due to loss of habitat and illegal poaching.

Resources: nationalzoo.si.edu, news.nationalgeographic.com, dailymail.co.uk