Thursday, December 17, 2015

Goanna Lizard: Venomous Reptile of Australia

Goanna lizard
Goanna Lizard
Courtesy of Pete Firminger
Goanna lizards are in fact Australian monitor Lizards. They have this name because early white settlers of Australia mistook the animals for the more familiar iguana lizards. There are more than twenty species of goanna lizards in Australia and they can be found nearly everywhere on the continent.

All species of goanna lizards are very similar in color, shape and appearance. They are dark grey, olive green or brown in color. Most of them also have grey, white or yellow patterns on their skin. They also have a large flap of skin on the neck that the animal has the ability to puff up when it feels threatened. One thing that varies greatly among the species of goanna lizards is size. The largest of the goanna are among some of the largest lizards in the world, but the smallest are very small compared to their counterparts. Goanna lizards range in size from less than a foot to 6.5 feet long.

Some goanna lizards live in trees, while others are terrestrial. However, even the terrestrial goannas have the ability to climb trees with ease. They can run bipedally or quadrupedally and are good runners over short distances. They are known to sometimes stand on their hind legs and, like other monitor lizards may fight each other this way. Some of these animals live near freshwater, where they can sometimes be seen swimming.

Goanna lizards mate at different times of the year, depending on the species. Northern Australian goanna lizards mate during the summer and southern Australian goanna mate during the winter. Eggs are laid in nests, burrows and even termite mounds. These lizards lay anywhere from three to eleven eggs at a time and the eggs incubate for 169 to 265 days before hatching.

Goanna lizards are carnivorous and will eat other lizards, small mammals, snakes, eggs, birds and insects. They actively hunt their prey and will dig large holes in the ground in search of food. They have hinged lower jaws, making it easy for them to swallow a meal whole. They also eat carrion, so they will sometimes be seen eating large animals by tearing chunks of flesh off of the carcass and swallowing them.

The bite of a goanna lizard does contain venom, though not in large amounts. Infections caused by their bite had been attributed to bacteria in the animals’ mouths, until it was discovered that they have venom glands in their mouths, much like a venomous snake does. However, bites from a goanna lizard could contain both bacteria and venom and they should be treated as such.


Smith, Deborah, The Sydney Morning Herald, November 18, 2005, retrieved, 9/13/09,

Australian Goannas, Our Monitor Lizards, retrieved 9/13/09,

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