Male gorillas often beat their fists on their chests. They do so to show who is the strongest in the group. However, it can also be a kind of greeting. Gorillas don’t just walk on the palms of their hands, but also on their knuckles. For this reason, they’re also known as knuckle-walkers.

• Fun Fact: Male gorillas can weigh up to 440 lbs (200 kg).
  

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