Snake dentition

Although most snake species are harmless to humans, several lineages have evolved venom with which to subdue their prey. This venom is typically delivered via specialized teeth ("fangs") located on the maxilla, a bone in the upper jaw.

General snake dentition

In most snakes, there are teeth on the dentary of the lower jaw (front-most jaw bone), the maxilla (outer front upper jaw bone), and the palatine bone and pterygoid, which form an 'inner row' of teeth. This 'inner row' can move separately from the rest of the jaws, and is used to help 'walk' the jaws over the prey. Some snakes, particularly burrowing snakes, have lost some or all of the teeth on various bones (in some cases only retaining a few lower or upper teeth)), but most snakes will have at least some teeth on each of the bones listed.

Categories

Most snakes can be placed into one of four groups, based on their teeth. The form of their teeth strongly correlates with venom and evolutionary lineage.

Aglyph

, the enlarged teeth are merely "scaled up", and are otherwise identical. Aglyphous snakes are non-venomous, and can be found in numerous families.

Opisthoglyph

.

Proteroglyph

have modified opening at the tip of the fang which allows them to spray venom at an attacker's eyes.

olenoglyph

. Their maxillae have been reduced to mere nubs which support only a single hollow fang on each, which can be half the length of the head (almost 2 inches long in large species). The fangs are typically "folded back" against the roof of the mouth, pointing backwards, to accommodate their great length. During a bite, the fangs swing forwards into position. While all snake jaws have numerous interconnections between the bones, the viper's skull has been modified into a series of interacting elements which cause the fangs to swing into biting position as a direct result of the jaws opening. Vipers open their mouths almost 180 degrees, and the fangs swing into a position to allow them to penetrate deep into the prey. While viper venom is typically less toxic than that of elapids, this system allows them to inject large quantities of venom deep into the prey animal.

Others

A few snakes do not conform to these categories. Atractaspis possess swinging fangs like a viper, but the fangs swing out sideways, allowing the snake to strike without opening its mouth, presumably to kill prey in small tunnels underground. The blind burrowing snakes (scolecophidia) typically have few teeth, often only in the upper jaw or lower jaw.