There are two species in southern Africa and they are the Nile Monitor or Water Leguaan (Varanus niloticus - Africa's largest lizard) and the Rock Monitor or Tree Leguaan (Varanus albigularis). (In places like Zimbabwe there are occasional sightings of Election Monitors - these are not strictly lizards and their impact on their environment is so negligible they might as well be extinct.)
The Nile monitor may possibly reach 2m, 60% of which would be tail, but this would be exceptional. Rock monitors are slightly shorter and bulkier, with tails slightly longer than the body.
Monitors are fearsome predators, hunting on and under the ground, in trees and (in the case of the Nile monitor) in the water. They differ from snakes in having movable eyelids and external ears, but they do have forked, snake-like tongues which they use in conjunction with the Jacobson's organ, a fluid-filled bi-lobed sensory organ in the roof of the mouth.
They will eat practically anything: insects, reptiles, frogs, small mammals up to the size of domestic cats, birds and eggs, carrion and rubbish.
Water monitors also catch fish and are among the most important predators of crocodile eggs. They have been observed using teamwork for this; one distracts the mother crocodile while others rush in to dig up the nest.
Water monitors are excellent swimmers, folding their legs in and using their tails like crocodiles, and can stay underwater for well over half an hour. They can run astonishingly fast over a short distance, and invariably head for water when disturbed.
Both Species occur in KSNR