Here's why:
* Flehmen Response: This is a curious behavior where a cat curls its upper lip back, exposing its teeth, and inhales deeply. It's not for smelling, but for detecting pheromones. The roof of a cat's mouth has a special organ called the vomeronasal organ, which detects these pheromones to help them understand information about other cats, like their gender, reproductive status, and even mood.
* Cooling Down: Opening their mouth can help cats regulate their body temperature, especially when they're hot.
* Vocalization: When cats want to meow, hiss, or purr, they need to open their mouth.
* Eating and Drinking: Obviously, they need to open their mouths to eat and drink!
So, while cats don't use their mouths for smelling, they do use them for many other important functions!