III.

PHYSICAL DESCRIPTION AND BEHAVIOR

Pythons are primitive snakes that, like their close relatives the boas, still show signs of lizard ancestry. Pythons have traces of a pelvis and two tiny spurlike hind limbs, usually better developed in the male. They also have two functioning lungs, one large and one small—more advanced snakes have only a single lung.

Pythons lay eggs—unlike most boas, which give birth to live young. Female pythons produce from 10 to 100 eggs, depending on the species, and wrap their bodies around their clutch (group of eggs) to keep it warm and defend it against predators. Pythons can even raise their body temperature by rhythmically twitching (“shivering”) their muscles to generate heat to help incubate the eggs. Incubation can last from two to three months. Baby pythons fend for themselves after hatching without parental care.

Pythons range from about 1 to 10 m (about 3 to 33 ft) long and can weigh up to 140 kg (about 300 lb). Female pythons tend to be larger than males. Because pythons are cold blooded, they grow relatively slowly in the wild. They may grow more quickly with sustained care in captivity. In some species males can reach sexual maturity in 18 months and females in four years. Depending on the species, pythons can live 20 or 30 years in captivity, and in some rare cases exceed 40 years. The snakes have shorter life spans in the wild.

Some species have as many as 400 sets of ribs. Their jaws can have up to 200 backward curving teeth, designed to grip prey and prevent it from pulling away. Pythons also have teeth on the roof of the mouth. Many of the bones in a python’s skull are loosely attached with ligaments or skin, allowing the snake to stretch and expand the shape of its head and jaws to aid in swallowing large prey. The lower jaws can unhinge from the upper jaws and the lower jaws can spread wide apart, giving pythons a huge gape.

Many pythons have striking skin patterns that help the snakes blend in with their surroundings and hide from potential prey or from predators. Blotches, spots, bands, or rings may resemble leaves, rocks, or ground cover, dappled with shadows. Some species have iridescent colors while others lack skin patterns. A few species can even shift their skin colors. Most pythons change color as they grow from juveniles to mature adults.

The reticulated python of Southeast Asia is among the largest snakes, reaching a length of 10 m (33 ft). Other well-known pythons are the 6.7-m (22-ft) Indian python, a favorite of snake handlers; a subspecies of the Indian python, the Burmese python, which can reach similar size; the 9.8-m (32-ft) African rock python; and the 1.5-m (5-ft) ball, or royal, python of equatorial Africa, which coils into a ball when molested. Other types of pythons include the 2-m (7-ft) green tree python, the 2.4-m (8-ft) diamond python, and the 3-m (10-ft) carpet python, all found in Australia and New Guinea.