Lizards do not possess the hollow, hypodermic teeth traditionally defined as true fangs in venomous snakes. A biological fang is a specialized tooth, often enlarged and grooved or hollow, that functions to rapidly inject venom. While most lizards have simple, non-venomous teeth, a few species have evolved specialized teeth and venom glands. However, their delivery system is mechanically distinct: lizards rely on a chewing motion to introduce venom, whereas snakes use a quick, forceful strike to inject venom.
The Straight Answer: True Fangs vs. Specialized Teeth
A true fang, as found in vipers and cobras, is a modified maxillary tooth that acts like a hypodermic needle for pressurized venom delivery. This structure allows for a rapid, deep injection of toxins with minimal contact time. In contrast, the specialized teeth found in venomous lizards, such as Gila Monsters, are deeply grooved, not hollow, and are located on the lower jaw. Lizard venom delivery is a passive process, relying on the venom flowing down these grooves by capillary action. This method requires the lizard to hold its bite and actively chew to work the venom into the tissue.
The Structure of General Lizard Dentition
The vast majority of the over 6,000 lizard species possess generalized teeth designed for holding and tearing prey, not for venom delivery. Lizard dentition is broadly categorized into two primary types based on how the teeth attach to the jawbone.
One attachment type is pleurodont, where the teeth are attached to the inner side of the jawbone, creating a stronger anchorage. Many common lizards, including iguanas, monitor lizards, and geckos, exhibit pleurodont dentition. A key feature of pleurodont teeth is that they are continuously shed and replaced throughout the animal’s life. The second type is acrodont dentition, where the teeth are fused directly to the top edge of the jawbone. This attachment is less secure, and once the teeth are lost or worn down, they are not replaced. Lizards such as chameleons and agamid species, like bearded dragons, possess acrodont teeth.
Specialized Venom Delivery Systems
The only lizards with a specialized venom apparatus are the Gila Monster (Heloderma suspectum) and the Mexican Beaded Lizard (Heloderma horridum), belonging to the family Helodermatidae. These lizards produce venom in modified salivary glands located in the lower jaw, which is transported through small ducts to the base of the lower teeth. The teeth have distinct longitudinal grooves running down their length, allowing the venom to travel up by capillary action and enter the wound as the lizard chews. This delivery mechanism is primarily defensive, intended to deter predators.
Another notable exception is the Komodo Dragon (Varanus komodoensis), which was historically thought to kill with septic bacteria but is now confirmed to have true venom glands. The Komodo Dragon’s system is structurally complex, with multiple ducts leading from the glands to openings located between their serrated, backward-curving teeth. Like the Heloderma species, the Komodo Dragon uses a bite-and-pull strategy to create deep wounds, allowing the venom to seep in and cause rapid blood pressure drop, preventing clotting and leading to shock.