If you saw the movie The Rescuers Down Under, then you may remember that the villan, Percival McLeach (voice of George C. Scott) had a pet lizard he called Joanna. This would make anyone familiar with the Australian lizards called goannas smile (as opposed to story elements, such as a young boy walking from Ayres Rock to Kakadu by lunchtime, which would make them groan or guffaw).
The word goanna is likely a corruption of iguana, and got tacked onto the animal by early settlers and explorers. The goanna is, however, a monitor lizard, not an iguana. (Etymological aside: some reference works suggest that goanna might alternatively have come from the African word leguaan. However, since leguaan is most likely a corruption of the French for iguana—l’iguane—no matter how it got to Australia, it all started with the iguana.)
There are about thirty recognized species of monitor lizard, 19 of which are indigenous to Australia. The largest monitor lizard is the famous and impressive Komodo dragon (Varanus komodoensis), which grows to about 10 feet in length and is the world’s largest lizard. But Australia’s giant perentie (V. giganteus) is nearly as impressive, at around 8 feet in length. (There is archaeological evidence that Australia once had a goanna that grew to in excess of 21 feet in length, but they became extinct about 30,000 years ago.)
On the other end of the scale, there are pygmy goannas that only grow to about 8 inches. The goannas that one most commonly sees, however, are from 2 to 4 feet in length—not giants, but still impressive.
Goannas (along with other monitor lizards) are carnivorous. Like most other carnivores, they have sharp teeth and claws. They are swift and clever hunters, and research seems to indicate a high level of intelligence, at least for a lizard.
During my several trips to Australia, I have seen a fair number of goannas of varying species, but the first one I saw live was during my visit to Kakadu, when we stopped briefly during our cruise at Yellow Water to watch a monitor making his way across a clearing near shore. This was no giant, but at roughly four feet in length, he still commanded respect. You can see that he is on the alert, because, despite our tip-toeing, he knew we were approaching.