Perentie

The perentie (Varanus giganteus) is a monitor lizard and ranks as the fourth-largest living lizard, smaller only than the Komodo dragon, Asian water monitor, and crocodile monitor. It inhabits arid areas west of the Great Dividing Range in Australia and is seldom spotted due to its shy nature and the isolation of its habitat from people. The International Union for Conservation of Nature lists it as a least-concern species. In many Aboriginal cultures, the perentie holds totemic significance, appears in the Ngiṉṯaka dreaming, and serves as bush tucker. Desert Aboriginal groups favored it as food and used its fat for medicine and ceremonies.

British zoologist John Edward Gray first described the perentie in 1845, naming it *Hydrosaurus giganteus* or "gigantic water lizard." George Albert Boulenger later reclassified it under the genus *Varanus*, where it belongs to the subgenus *Varanus*.

The perentie lives in the arid deserts of Western Australia, South Australia, the Northern Territory, and Queensland. Its preferred habitats include rocky outcrops and gorges with hard-packed soil and loose stones.

As Australia’s largest lizard, the perentie can reach 2.5 meters (8 feet 2 inches) in length and weigh up to 20 kilograms (44 pounds), with some possibly growing to 3 meters (9 feet 10 inches) and 40 kilograms (88 pounds). Despite its size, it is notably lean compared to other large monitors, such as the rock monitor. Its head and neck feature a creamy-white background with a reticulated pattern of black lines and flecks. The body is yellow or cream with brown rosettes on the back, and the limbs are dark with white spots.

In late 2005, researchers at the University of Melbourne found that all monitor lizards may be somewhat venomous. Previously, bites were thought to cause infection from mouth bacteria, but the study showed immediate effects stem from mild envenomation. Bites from Komodo dragons, perenties, lace monitors, and spotted tree monitors have caused swelling within minutes, localized blood clotting disruption, and shooting pain lasting hours. However, biologist Kenneth V. Kardong and toxicologists Scott A. Weinstein and Tamara L. Smith argued that labeling all monitors venomous underestimates the varied roles of oral secretions in reptiles, narrows the view of these secretions, and misinterprets reptilian evolution. They noted that oral secretions serve many biological purposes beyond quickly killing prey and that calling the entire clade venomous overstates the danger, misleads medical risk assessments, and confuses biological understanding of squamate biochemistry.

Perenties typically avoid people and often flee before being seen. They dig burrows quickly for shelter and use their long claws to climb trees easily. They frequently stand on their hind legs and tail—called "tripoding"—to survey the terrain, a common behavior among monitors. They sprint fast on all four legs or just their hind legs. Like most goannas, they either freeze flat on the ground or run when detected. If cornered, they defend themselves with claws, teeth, and a whip-like tail, inflating their throat and hissing as a display. They may lunge with an open mouth as a bluff or attack. Their bite causes serious damage from both teeth and oral secretions.

As apex predators, adult perenties have no natural predators in their range. They are highly active carnivores that eat mostly reptiles, small mammals, and occasionally birds like diamond doves. They hunt live prey but also scavenge carrion. Reptilian prey includes lizards such as skinks and agamids, and less often snakes. They practice intraguild predation, consuming other monitor species like ridge-tailed monitors, black-headed monitors, Gould's monitors, and Argus monitors. They also eat smaller perenties—for instance, a 2-meter perentie killed and ate a 1.5-meter one. Other lizard prey includes central bearded dragons and long-nosed water dragons. Coastal and island individuals often eat sea turtle eggs and hatchlings, and hide under vehicles to ambush scavenging gulls. Mammalian prey includes bats, young kangaroos, other small marsupials, and rodents. They occasionally forage in shallow water and can kill kangaroos, dismembering large prey with their forelimbs and claws. Adults mainly eat vertebrates, while young perenties feed mostly on arthropods like grasshoppers and centipedes. Prey is usually swallowed whole, but large items are torn into chunks.

The perentie lays its eggs in termite mounds.