The infraorder, to which boas, pythons and anacondas belong, has around 20 genera and more than 70 different species. Boas belong to the Boidae family, while the pythons belong to the Pythonidae family. Both families share a number of primitive characteristics. Nearly all have a relatively rigid lower jaw with a coronoid element, as well as a vestigial pelvic girdle with hind limbs that are partially visible as a pair of spurs, one on either side of the vent. None of them have extremities. Boids are, however, distinguished from the pythons in that their skeleton is different, and that they give birth to live young, while the pythons lay eggs. Pythons are limited to Eurasia, while boas live all over the planet.
The most popular of all boa species is the Boa Constrictor, native to the Central and South-American rainforests. The colour pattern consists of a ruddy brown ground colour, becoming a rich brick red on the tail. Dorsally, the ground colour is overlaid with a series of large tan-coloured saddles. Adult size averages 3 metres, specimens of up to 4 metres are not unusual. Boas of bigger size are often mistaken for anacondas (water living boas) or Asian pythons due to the legends that have been created around them.
Boa Constrictor, Boa constrictor
How are they? The Boa Constrictor is a big, non-venomous tropical snake. Looking from above, its head is triangular and contrasts with the slim neck. The ground colour is from dark-brown to light rose, overlaid by a series of large, tan-coloured saddles. A dark crossband runs from the nose to the neck, underlining the eyes on each side of the head.
How to differentiate males and females? The males are smaller than the females. Furthermore, the anal spurs in males are larger and more conspicuous than in females. These spurs are used by the male to grip and stimulate the female during copulation.
How is the species geographically distributed? From the Columbian Andes to the north of Argentina and Paraguay, but also on the islands of Trinidad and Tobago.
Where do they live? In woodlands, savannahs and swampland.
What do they feed on? Birds, reptiles and small mammals. The Boa Constrictor is a nocturnal hunter and detects its prey by the differences in temperature.