Goanna is the name used to refer to any number of Australian monitor lizards of the genus Varanus, as well as to certain species from Southeast Asia.
There are around 30 species of goanna, 25 of which are found in Australia. They are a varied group of carnivorous reptiles that range greatly in size and fill several ecological niches. The goanna features prominently in Aboriginal mythology and
Australian folklore.
Not all goannas are gargantuan. Pygmy goannas may be smaller than a man's arm. The smallest of these, the short-tailed monitor (Varanus brevicuda) reaches only 20 cm in length. They survive on smaller prey such as insects and mice.
Goannas combine predatory and scavenging behaviour. A goanna will prey upon any animal it can catch that is small enough to eat whole. Goannas have been blamed for the death of sheep by farmers, though most likely erroneously, as goannas are also eaters of carrion and are attracted to rotting meat.
Most goannas are dark in colouration, whites, greys, browns, blacks and greens featuring prominently. Many desert-dwelling species also feature yellow-red tones. Camouflage ranges from bands and stripes to splotches, speckles and circles, and can change as the creature matures, with juveniles sometimes being brighter than adults.
Like most lizards, goannas lay eggs. Most lay eggs in a nest or burrow, but some species lay their eggs inside termite mounds. This offers protection and incubation; additionally the termites may provide a meal for the young as they hatch. Unlike other species of lizards, goannas do not have the ability to regrow limbs or tails.
Goannas are found throughout most of Australia, except for
Tasmania, and manage to persist in a variety of environments. Most species are known to climb trees or outcrops; there are plenty of primarily arboreal species. The lace monitor (Varanus varius) is probably the best-known amongst these, but is not the most common. The lace monitor is the second largest of all goannas, reaching lengths of up to 2 metres. Other more common tree goannas, such as the Timor tree monitor (Varanus timorensis) and Mournful tree monitor (Varanus tristis) do not grow to quite such lengths, averaging only a few feet nose to tail.
The name goanna might have been derived from iguana, as early European settlers likened goannas to the South American lizards. Over time, the initial vowel sound was dropped. A similar explanation is used to link possum to the American opossum.
Another possibility is that the name might have been derived from the South
African term for a monitor lizard leguaan, as the Cape of Good Hope was a popular refresher stop for immigrant ships to Australia from Britain.