The world of lizards contains a remarkable range of sizes, from species small enough to fit on a fingertip to massive reptiles that dominate their ecosystems. When people ask what big lizards are called, the answer is not a single name but a collection of distinct families that independently evolved to achieve great size. The largest lizards today are recognized by their substantial length and mass, often exceeding two meters long.
Monitor Lizards The Defining Group
The most prominent and widespread group of large lizards is the Monitor family, scientifically known as Varanidae. This family comprises the genus Varanus, which includes approximately 80 species distributed throughout Africa, Asia, and Australia. Monitors are characterized by their powerful build, long necks, strong limbs, and non-detachable tails, making them efficient terrestrial, arboreal, and semi-aquatic predators.
Monitors use their long, forked tongues to sample the air for chemical cues, much like snakes do. This specialized chemoreception allows them to locate prey and carrion across vast distances. Their varied diet includes everything from insects and eggs to large mammals, depending on the species and its habitat. The size variance within the family is immense, ranging from the diminutive short-tailed monitor up to the largest terrestrial lizard in the world.
The World’s Heaviest and Longest Lizard
The Komodo Dragon (Varanus komodoensis) stands as the largest living lizard. Found only on a few Indonesian islands like Komodo, Rinca, and Flores, this reptile can regularly reach lengths of 3 meters (10 feet). While some individuals have been recorded weighing over 150 kilograms (330 pounds), a typical large male is closer to 70 kilograms (150 pounds), making it the heaviest lizard species globally.
The Komodo Dragon functions as an apex predator in its native habitat, utilizing ambush tactics and a specialized bite to take down large prey, including deer and water buffalo. Its powerful bite delivers venomous proteins that prevent blood clotting and cause a rapid drop in blood pressure in its victims.
Other Families Containing Large Species
While monitors dominate the large lizard category, several other lizard families also contain large members. In South America, the Tegu lizards (Family: Teiidae) are a notable example, with the Argentine black and white tegu (Salvator merianae) being the largest species. These heavy-bodied lizards can reach total lengths of up to 1.5 meters (5 feet) and weigh as much as 9 kilograms (20 pounds). Tegus are omnivores, consuming a varied diet of fruit, eggs, and small animals.
Another family containing large species is the Iguanidae, which includes the Green Iguana (Iguana iguana), a large herbivore found across Central and South America. The Green Iguana can grow to lengths over 2 meters (6.6 feet), with large males sometimes exceeding 9 kilograms (20 pounds) in weight. The Helodermatidae family contains the Gila Monster and the Mexican Beaded Lizard, which are the only two lizard species outside of the monitors known to produce a medically significant venom. The Mexican beaded lizard sometimes reaches nearly a meter in length and weighs up to 4 kilograms (9 pounds).