Perentie

Perentie
Perentie in the wild
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Varanidae
Genus: Varanus
Subgenus: Varanus
Species: V. giganteus
Binomial name
Varanus giganteus
(Gray, 1845)
Distribution of the perentie

The perentie (or perente) (Varanus giganteus) is the largest monitor lizard or goanna native to Australia, and the fourth-largest living lizard on earth, after the Komodo dragon, Asian water monitor, and the crocodile monitor. Found west of the Great Dividing Range in the arid areas of Australia, they are not a common sight because of their shyness and the remoteness of much of their range from human habitation.

Their status in many Aboriginal cultures is evident in the totemic relationships, and part of the Ngiṉṯaka dreaming, as well as bush tucker. They were a favoured food item among desert Aboriginal tribes, and the fat was used for medicinal and ceremonial purposes.

Description

The lizard can grow up to 2.5 m (8 ft 2 in) long, although the average length is around 1.75 to 2 m (5 ft 9 in to 6 ft 7 in) and weigh up to 15 kg (33 lb) — maximum weight can be over 20 kg (44 lb). Their rival for the title of the third-largest lizard is the crocodile monitor, which although often longer, exceeding 2.4 m in length, is lighter and less bulky than the perentie. However, perenties are relatively lean lizards and are less bulky than either the Komodo dragon or the Asian water monitor.

Venom

In late 2005, University of Melbourne researchers discovered that perenties (Varanus giganteus), other monitors and iguanians may be somewhat venomous. Previously, bites inflicted by these lizards were thought to be simply prone to infection because of bacteria in the lizards' mouths, but these researchers have shown that the immediate effects are caused by mild envenomation. Bites on human digits by a lace monitor (Varanus varius), a Komodo dragon (V. komodoensis) and a spotted tree monitor (V. scalaris) have been observed to produce similar results: rapid swelling within minutes, localised disruption of blood clotting, and shooting pain up to the elbow, with some symptoms lasting for several hours.[1]

Other scientists have stated that the suggestion of venom glands "...has had the effect of underestimating the variety of complex roles played by oral secretions in the biology of reptiles, produced a very narrow view of oral secretions and resulted in misinterpretation of reptilian evolution", "...reptilian oral secretions contribute to many biological roles other than to quickly dispatch prey", and "[c]alling all in this clade venomous implies an overall potential danger that does not exist, misleads in the assessment of medical risks, and confuses the biological assessment of squamate biochemical systems".[2]

Distribution and habitat

Perenties are found in the arid desert areas of Western Australia, South Australia, the Northern Territory, and Queensland. Their habitats consist of rocky outcroppings and gorges, with hard-packed soil and loose stones.

Behaviour

Perenties are not a common sight in Australia. They generally avoid human contact and will retreat before they are seen. Being able diggers, they can excavate a burrow for shelter in only minutes. Their long claws enable them to easily climb trees. They often stand on their back legs and tail to gain a better view of the surrounding terrain. This behaviour, known as "tripoding", is quite common in monitor species. Perenties are fast sprinters, and can run using either all four legs or just their hind legs.

Typical of most goannas, the perentie will either freeze (lying flat on the ground, and remaining very still until the danger has passed) or run if detected. If cornered, this powerful carnivore will stand its ground and use its arsenal of claws, teeth, and whip-like tail to defend itself. They inflate their throats and hiss as a defensive or aggressive display, and strike at opponents with their muscular tails. Perenties will also lunge forward with open mouths, either as a bluff or as an attack. The bite of a perentie can do much damage, not only from the teeth, but also because of the oral secretions from their mouths.

Diet

As a carnivore, the perentie feeds on a wide variety of prey. Though normally active hunters, they hide and ambush prey when the need arises. Depending on their size, they hunt insects, lizards, fish, birds, and small animals such as rats and rabbits. Larger individuals will also hunt large animals, such as small kangaroos, wombats, and even lone dingoes. They have also been known to hunt and eat pets, such as cats and small to medium-sized dogs. A perentie attacks by either biting with its strong jaws or whipping the prey with its long, powerful tail; their tails are so strong, they can easily break a dog’s leg with a single blow. Once they bring their prey down, they shake it to death in their strong jaws and then swallow it whole. They use their tails both offensively and defensively. Cannibalism among perenties has been observed; feces from wild perenties often contains monitor teeth, claws, and other evidence of their cannibalism.

References

  1. ↑ Fry, Brian G., et al. (2006). Early evolution of the venom system in lizards and snakes. Nature, 439: 584-588. DOI:10.1038/nature04328
  2. ↑ Weinstein, Scott A.; Smith, Tamara L.; Kardong, Kenneth V. (14 July 2009). "Reptile Venom Glands Form, Function, and Future". In Stephen P. Mackessy. Handbook of Venoms and Toxins of Reptiles. Taylor & Francis. pp. 76–84. ISBN 978-1-4200-0866-1. Retrieved 18 July 2013.

Further reading

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