Identification
Goannas (known as monitor lizards in other countries) are well represented in Australia and 19 species are found in Queensland.
This group contains the world’s largest living lizard, the Komodo Dragon (Varanus komodoensis) from Indonesia which grows to more than 3 m. The Komodo Dragon is most closely related to the Lace Monitor (Varanus varius) pictured above, and there is fossil evidence suggesting that Komodo Dragons once also occurred in Australia.
Goannas have small, non-overlapping body scales, strong limbs, a powerful tail, moveable eyelids and long, recurved teeth. They have forked tongues that are flicked in and out in a snake-like manner and walk with a swaggering gait. The Queensland species range in size from the tiny, 23 cm long, Short-tailed Pygmy Monitor (Varanus brevicauda) to the 2.4 m Perentie (Varanus giganteus).
Most goannas look fairly similar, but those that dwell in rock crevices have spiny tails (for example, the Spiny-tailed Monitor, Varanus acanthurus and Storr’s Monitor, V. storri). The Canopy Goanna (V. keithhornei) and the Emerald Monitor (V. prasinus) are equipped for life in the trees and have prehensile tails while the semi-aquatic goannas (Mertens’ Water Monitor, V. mertensi and Mitchell’s Water Monitor, V. mitchelli) have compressed tails for swimming.
Habitat and Range
All goannas are carnivorous, consuming anything they can overpower; insects, small mammals, frogs, birds and reptiles. The larger species will even tackle large, dangerously venomous, snakes. Goannas will also scavenge and it is not unusual to see Lace Monitors emerging from the carcasses of dead cows.
All goannas lay eggs; most bury these in the ground but some use termite nests. The female Lace Monitor uses the nest of tree-dwelling termites as an incubation chamber for her eggs. The termites repair their nest over the eggs, thus sealing them in. The hatchling goannas are incapable of digging their way free from a termite nest and are released by an adult Lace Monitor, presumably their mother.
Did you know?
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Text © The State of Queensland (Queensland Museum)
Image © Jona Photography