Another question I'm sometimes asked is where the bit goes. "Don't they have teeth in there?"
Image source: Wikimedia Commons, public domain.
This is a horse skull. As you can see, the horse has no less than six sets of molars. Grass takes a lot of breaking down to make it digestible. At the very front of the mouth you see two sets of incisors and one set of canines.
And no premolars. Because of the length of the horse's head and the absence of premolars, there's a substantial gap between the canines and the first set of molars - and that's where the bit goes. There's nothing in that gap but bare gum. We refer to this as the "bars" of the mouth. I'll talk more about horse teeth tomorrow!