Varanus giganteus
Open 7 Days from 9am to 4pm
This magnificent monitor lizard is the largest lizard in Australia, and among the 4 largest in the world! Seldom encountered in the wild, it is a reclusive dweller of central Australian deserts.
WHAT’S IN A NAME?
Perentie is an anglicized version, coined in the early 20th century, of the First Nations word for this lizard—probably pirrinthi from the Diyari language of south-central Australia.
The genus name Varanus is derived from the Arabic word ‘waral’ or ‘waran’ meaning ‘lizard beast’. The species name is easy: giganteus simply means huge!
Perenties belong to the family of monitor lizards, so-called because of the habit of standing upright on their hind legs, appearing to ‘monitor’ the horizon for danger.
Varanid lizards are also called goannas, derived from the name given them by early European settlers because of their resemblance to iguanas of South America. In fact, monitors and iguanas belong to different families of lizard.
WHERE DO THEY LIVE?
Perenties are found only in Australia.
They live in arid desert areas across central Australia, from Western Australia into South Australia, Northern Territory and Queensland. They are also found on islands off the coast of Western Australia, with a large population living on Barrow Island.
Their preferred habitat is rocky hills and outcrops. Areas with hard-packed clay or rocky soil are preferred, because they shelter in burrows which they dig with their powerful front legs and claws. These may be quite extensive with several entrances and escape exits. Perenties are also known to take over burrows from other species. Burrows provide shelter from the extreme heat and cold in desert environments.
Although primarily ground dwellers, they readily climb trees if disturbed.
Perenties are rarely encountered in the wild, because of their reclusive nature and the remoteness of most of their range.
What do they Look Like?
Like all monitor lizards, they have long necks, powerful tails and claws and thick, strong limbs.
Their colouration is distinctive, and quite spectacular: brown above with large pale blotches across the back and sides. Each blotch is edged with dark brown or black. These run together to form a reticulated pattern across the sides of the neck, on the face and on the throat.
This pattern is unique and can be used to distinguish individual lizards. The limbs are darker, also with pale spots, and the belly is light in colour.
Young perenties are more brightly coloured than adults.
The strong tail, whip-like is about 1.3 times the length of the body. It is used to defend itself, slashing sideways with incredible speed and force. .
This is Australia’s largest lizard!
Average length is about 1.6 metres (5.25 feet) overall. Reports of much larger individuals, over 2 metres, are unconfirmed. Very large specimens can weigh over 10 kg (22lb). Males grow larger than females.
Fun Fact: Monitor lizards are one of the few lizard species that have a forked tongue—like that of a snake!
What do they Eat?
Perenties are apex predators, and are strictly carnivorous.
They hunt a wide variety of prey animals, including lizards, mammals, birds, and arthropods, and will also eat carrion. Reptiles including other monitors and even smaller perenties make up the largest part of their diet! They have been seen to excavate sea turtle nests to eat eggs and young turtles.
The proliferation of introduced rabbits has allowed them to expand their range in central Australia.
Perenties have evolved some amazing adaptations to enable their hunting lifestyle.
They have an incredible sense of smell. The deeply forked tongue is continually flicking in and out, picking up scent molecules from the air. These are transferred back to the Jacobson’s organ in the roof of the mouth, which can interpret the type of prey, and whether it is to the left or the right!
Fun Fact: They are very fast runners, reaching speeds of about 40 kph (25 mph)! While they are running, powerful muscles on the sides of their neck expand and contract like bellows, pumping a large volume of air into the lungs. This enables them to outrun fast-moving prey!
Once captured, the prey animal is killed by violent shaking. Small prey is swallowed whole, but larger animals are torn into bite-sized chunks.
Perenties have glands along their lower jawline that secrete mild toxins. The function is debatable, as these chemicals would not act quickly enough to disable prey. Even if a person (such as a zookeeper or field researcher) is a bitten, more damage is likely to be done by the sharp, serrated teeth. One theory is that the secretions act as a microbial agent, ‘cleansing’ the mouth when the animal has eaten carrion. More research is needed!
Breeding and Raising the Young
Perenties are solitary animals with large home ranges, coming together only during breeding season.
Breeding occurs in spring and early summer, coinciding with the wet season across northern Australia.
Males engage in ritual combat, wrestling with each other chest to chest till one is forced to the ground. The victor may bite the other male.
The successful male may then mate several times over a period of days. Courtship includes head bobbing, licking and nuzzling the female.
Females lay only one clutch per year, comprising an average of 6 to 12 eggs.
They may be deposited in deep sandy soil, but often are laid inside a termite mound. The insects’ activity keeps the temperature and humidity at an optimal level for the 220 days until the eggs hatch!
Females of other species of monitor lizards have been known to return to the mound to excavate the nest at hatching time.
The newly-hatched young receive no parental care.
No long term field studies have been carried out to determine life span in the wild. The longest that a perentie has been held in captivity is 19 years.
Status in the Wild
The perentie is listed as ‘Least Concern’ by the IUCN. There are no major threats identified.
First Nations people have a deep connection to the perentie, as they have lived side by side for tens of thousands of years. They are an important source of food. The fat is important both ceremonially and medicinally. They have significant totemic importance, and feature in Dreamtime stories; for example: “How the Perentie and Goanna got their Colours’”. In artworks, they are depicted as symbolic spiritual motifs.
Perentie at Billabong Sanctuary
Since early 2017 we have been privileged to be home to Simpson, a magnificent perentie!
You can meet him in his enclosure just past the echidnas. There is even a large viewing window for the littlies!
Perenties are very curious, intelligent animals, and require a lot of enrichment to keep them mentally and physically active. Our rangers are doing target training, teaching him to come for food.
All these photos are of Simpson—isn’t he awesome!
Further Reading
Reptiles & Amphibians of Australia. Harold G Cogger. Reed Books Australia
Perentie Facts: https://www.activewild.com/perentie-facts/
Atlas of Living Australia https://www.ala.org.au/
https://biocyclopedia.com/index/monitor_lizards/varanus_giganteus.php
https://www.youtube.com/watch?v=bsC1dzwPs2k Wicked Wildlife showcases Perenties
Dr. Timothy Jackson (2020), “Are monitor lizards venomous? (the Tale of Toxicofera, part 4)”, University of Melbourne.
