Monitors swallow small prey or pieces of large prey whole rather than chew it as do iguanas and other lizards. Like snakes, they have a strong bony roof to the mouth which protects the brain from being damaged by the passage of large mouthfuls. They can also greatly increase the size of their mouth cavity by spreading the hyoid apparatus and dropping the lower jaw. Other similarities with snakes are the shape of the vertebrae, the chamber structure of the heart, and the absence of a urinary bladder. Powerful legs allow them to run swiftly.
Monitors can get quite nasty if brought to bay.
At first they inflate their bodies and hiss. Then they attempt to deter any attack by violently lashing the tail like a whip. Finally they may attack by grabbing their adversary with powerful jaws and clawing with their feet. The largest is the Komodo Dragon at ten feet long, and the smallest is the eight inch short-tailed monitor of Australia. One male in the African section.