Кваока виглядає щасливою через форму рота але насправді просто охолоджується

The quokka's mouth is shaped in such a way that it just always looks like it's smiling. And when quokkas stick out their tongues while grinning? They're really just trying to cool off. Still, they do also look pretty happy when they're getting petted by tourists, so maybe they are actually happy!It's called the world's happiest animal for a reason. It'd be hard to tell if a quokka was angry at you. The fluffy marsupial's often dubbed "the world's happiest animal" thanks to its cheerful disposition and trust of humans.

National Geographic