amethystine python, (Simalia amethistina), long, slender, nonvenomous snake belonging to the family Pythonidae. The amethystine python inhabits mainly coastal rainforests in Indonesia, New Guinea, and northern Australia. The snake is not currently at risk of extinction and is considered an invasive species in some areas outside its native range, especially South Africa. It is the longest python in Australia.
Adult amethystine pythons average 3–3.7 meters (10–12 feet) in length, but a few giant individuals of more than 8.5 meters (28 feet) long have been recorded. The amethystine python is light yellowish gray to olive brown in color with darker splotches or bands. In sunlight the smooth scales shine and sparkle with a blue-purple iridescence, giving the snake its name (an amethyst is a clear purple or bluish violet variety of quartz). The snake has large symmetrical scales on the crown of its head and has an array of heat-sensing pit organs embedded in the lip scales that can detect infrared radiation. These enable the snake to “see” objects whose temperature exceeds that of the surrounding environment—a useful adaptation for locating prey at night.
The amethystine python is a constricting snake and is active from dusk to dawn, usually alongside streams and rivers. When hunting, it lies in wait for prey—mainly birds and mammals—to pass. Then it strikes out, capturing the prey with its teeth and squeezing the animal with its body until the prey is dead.
Like other pythons, the amethystine python is oviparous (egg laying) rather than viviparous (live-bearing). Mating takes place in cool weather. Clutches can contain as many as 21 large eggs. Females coil around their eggs and incubate them for as long as three months. When the air temperature begins to drop, she generates heat by shivering in a series of minuscule muscle contractions and thus maintains an elevated and fairly constant incubation temperature. Hatchlings are 61–66 cm (24–26 inches) long.