Water Monitor

Part of the Lizards and Snakes: Alive! exhibition.

Alert and intelligent, equipped with keen senses and saberlike teeth, Water Monitors are extreme carnivores.


These long forks make the monitor's tongue one of its most powerful tools for hunting. How? By providing directional cues. If the left fork picks up more of a prey animal's scent than the right, for example, the lizard will move to the left.

Many squamates, including monitors and snakes, flick their tongues to sample the surroundings for chemical compounds. They transfer those chemicals to sensors--called vomeronasal organs--in the roof of the mouth. Monitors have the longest tongues of any limbed lizard that uses its tongue to detect scents.

Water Monitor display case
Water Monitor display case
© AMNH / Roderick Mickens


These strong, curved claws can tear flesh and inflict fearsome wounds. Water Monitors eat only meat and sometimes tackle prey nearly their own size.




Water Monitor
© AMNH / Roderick Mickens


The bowed legs are powerful, and the Water Monitor is very fast for its size. Speed, endurance and the intelligence to outwit prey animals make it a dangerous predator.


All monitors are about the same shape and proportion as this one--but some are much smaller, others much bigger. At one end of the scale there's a 20 centimeter (nine inch) Short-tailed Goanna; at the other, the three meter (10 foot) Komodo Dragon. Megalania, an extinct monitor, grew to six meters (20 feet) or more.

Meet the Family

This family, Varanidae, includes about 60 species. They differ in size and color pattern but are alike in shape. Most monitors live in Australia--their name there, "goannas," comes from the word "iguana"--with only a few species in Africa and Asia. Large monitors are often top predators in their environments.

Komodo dragons (Varanus komodoensis)
Martin Harvey / NHPA

Komodo Dragon

Varanus komodoensis

Unknown to science until 1910, the Komodo Dragon is the largest living lizard. Its long, curved teeth and its strength, speed and intelligence make it a deadly ambush predator. Komodo saliva harbors more than 50 types of bacteria; four of them can cause infections that aren't treatable with known drugs.

Fast Facts

NAME: Water monitor; Varanus salvator
SIZE: 2.5 meters (8 feet)
RANGE: Southeastern Asia, Indonesia
DIET: Other vertebrates