monitor, any of various, mostly tropical lizards. A monitor lizard has a heavy body, long head and neck, long tail that comes to a whiplike end, and strong legs with sharp claws. Its slender, forked tongue is protrusible. Monitors range in size from the 8-in. (20-cm) short-tailed species of W Australia to the 10-ft, 300-lb (3-m, 136-kg) Komodo dragon, the giant among living lizards, that lives on the small Indonesian island of Komodo and some smaller neighboring islands. Some monitor species spend their lives in trees, and others inhabit lakes and rivers; they can be found on the oceanic islands and continents of the Eastern Hemisphere in all types of warm habitats, from tropical forest to desert. They feed on various kinds of animal matter, including eggs, rats, frogs, and decaying meat. The larger species will attack small deer and pigs. They often tear the prey with claws and teeth, but generally swallow it whole or in large chunks. Monitors lay from 7 to 35 leathery eggs, usually in holes in the ground or in trees. They are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Varanidae, genus Varanus.