Basic Set: Characters 91 mentions thrust-1
- an automatic grapple if a bite hits (GURPS Martial Arts: Technical Grappling would later suggest applying the same Control Points as damage, but this only works if Striking ST and Lifting ST are same)
- cannot bite the skull if same SM or smaller
- limbs can only be crippled on critical hits, and even then only with certain results
- targeting joints (tendons) are an exception
- bites count as one-handed grapples
- Worrying on subsequent turns
- advanced options if your SM is higher
- Born Biters
GURPS Zombies page 108 under "Biting 101" clarified some issues:
- When using Move and Attack to bite, the “cannot parry” restriction becomes “cannot dodge
- Size Modifier and Reach (p. B402) affects arms, not teeth.
- If someone tried and failed to grapple the (zombie’s) head or neck .. then on the (zombie’s) turn immediately following the attempt, the zombie can opt to chomp that person’s hand without the usual -4 to hit.
- Zombies are not given any advantage reflecting this benefit so it could be interpreted as a general rule for all biters.