How are viper fangs different from cobra fangs?

The primary difference between the fangs of vipers and cobras lies in their structure and mobility, which reflect their distinct evolutionary adaptations for delivering venom.

• Viper Fangs: Vipers (family Viperidae) possess long, tubular fangs that are attached to a short, blunt, and rotatable maxillary bone. This mechanism allows the fangs to fold back against the roof of the mouth when not in use and swing forward into a striking position when the snake opens its mouth.12
• Cobra Fangs: Cobras (family Elapidae) have short, hollow fangs that are fixed in a permanent, upright position at the front of the upper jaw. Because these fangs are stationary, elapids typically strike with a downward stab and may follow up with a chewing motion to ensure venom delivery.312

While most cobras have a straight canal for venom, some species—known as spitting cobras—have evolved specialized fangs with a canal that turns forward to a small opening on the front surface, allowing them to propel venom defensively at a distance.4