Family Boidae (Pythons and Boas)
Sub-family Pythoninae (Pythons)
Unlike the Boas, which are mainly confined to the Americas, the Pythons are restricted to Africa, Asia and Australasia. Pythons and Boas are the largest snakes in the world, and Pythons are the largest Australian snakes.
Python taxonomy is currently in a state of dispute. The scientific names used in the following text correlate with the consensus view of Australian herpetologists as of year 2001, which in turn reflects the taxonomy of Hoser (2000). However it is highly likely that different names will be in use in the future. (See section on 'Problems of Python classification and Hybrid Pythons')
Pythons are in general well known. They are slow-moving, heavy-bodied snakes that kill their food by constriction, and although they lack venom glands, larger specimens can give a nasty bite. There are more than a dozen recognised species in Australia, ranging in size from the 60-cm Ant-hill Python Antaresia perthensis to the 4-m plus Scrub Python Austroliasis amethistina.
Pythons possess pelvic spurs, which appear to be remnants of hind legs, around the vent. These have the appearance of being nothing more than a modified scale. In some types of Python these spurs are larger in males than females. They are used when mating. The male Python erects the spurs and digs them into the female while moving over her when attempting to copulate.
As opposed to Boas, which are live-bearers, all Pythons lay eggs, which they coil around and incubate until they hatch. Some Pythons can apparently spasmodically twitch their muscles, or 'shiver', and increase the temperature of their bodies and eggs, when incubating the eggs, as is
necessary. Some Pythons have been known to raise the temperature of their eggs by as much as 6 degrees Celsius above that of the ambient air temperature.
Most Python eggs take two or three months to hatch.
With the exception of the Black-headed Python Aspidites melanocephalus and the Woma Aspidites ramsayi, all Australian pythons possess heat sensitive pits in the labial scales, below the lower jaw. Tests have shown these pits to be sensitive to temperature variations of as little as one tenth of one degree Celsius. The pits presumably aid these Pythons in their location of warm-blooded prey.
The above was from the book Australian Reptiles and Frogs by Raymond Hoser and now available on a fantastic CD-Rom along with a vast amount of other information, papers and the like on reptiles, frogs and other wildlife.