Goannas Monitors and Earless Monitor: Varanidae

These lizards are active during the day. Those that live on land spend their nights in the hollow of a tree, a burrow that they dig, or some other hiding place. Many of them enter the water at times and are good swimmers. A few, such as the Nile monitor and Merten's water monitor, only come out of the water to sunbathe, or bask, on shore. The females also leave the water to dig holes along the shoreline, where they lay their eggs.

Many species in this family hide themselves when they hear people coming, so people often see little but their footprints. When they cannot hide, these lizards will defend themselves. They will typically flatten out from side to side and puff out their cheeks, which makes them look larger. A few even stand up on their hind legs. They also hiss. Some of the larger species can be quite dangerous, because they can swing their tail around with great speed and use it as a whip to strike the attacker. The Komodo dragon is large enough to kill humans with bites from its powerful jaws.

During the breeding season, males will fight over females. Their fights are wrestling matches in which two males stand belly to belly, grip each other with their arms, and try to knock one another down. Smaller species wrestle while lying on the ground. The winning male then courts the female by flicking his tongue over her snout and body. After mating, the females lay eggs in underground burrows, occasionally dug in the middle of termite nests or ground-built bird nests. Depending on the species, she may lay two to sixty eggs. The smallest species lay the fewest eggs, and the largest lay the most.