Mouth (hit location)

Mouth is a hit location in the face, presumably -6 or worse to hit since the face is -5. By comparison the nose and the jaw are -6.
It is possible to have a mouth (and bite) without having a jaw that can be targeted to cripple the use of the mouth.
Jaw is an absent hit location for No Face (included as part of No Head) yet there is an example in Fantasy of a "No Head" creature which can still bite.
==Racial alternatives to biting==
Toolkit 2 mentions:
:an animal whose mouth lacks a biting surface (such as teeth or a beak) might instead have the ability to secrete digestive juices
on its food, like a starfish, causing 1d-3 corrosion damage.
1d-3 Corrosion Attack is worth 0.1 dice, a base cost of 1 even without applying the Melee Attack limitation.
"Digestive juices" is something more animals are probably assumed to have as Internal Advantages at 1/5 price, the starfish example to "secrete" would be in reference to damaging EXTERNAL foes it has not swallowed.
*sort of like you need to chew food to crush it into smaller bits for it to actually fit through your esophagus in your neck
Conversely, biting is actually considered much more valuable since Weak Bite is worth several points, as is No Teeth.
The reason for that isn't very clear in Basic Set where all it was is a Crushing Attack, but it makes more sense by MA where it gains Grappling capability, making it armlike, and Worrying which allows no-roll damage.
Category:Hit Locations