Members of both families lack scales and pelvic fins.  They inflate themselves with water to become more difficult for predators to swallow or wedge themselves into the reef.  The caudal fin is reserved for short dashes while the other fins provide primary locomotion.  Puffers have short velcro-like spines and a pair of fused teeth in each jaw.  Porcupinefishes have stout spines or burrs and each jaw consists of a single cutting edge.  They are carnivorous and eat anything available but shellfish are preferred.  Members of the genus Canthigaster are known as Tobies.

Mouth showing four teeth