Twig Snake

The Twig or Bird Snakes of the genus Thelotornis are a group of back-fanged colubrid snakes in the family Colubridae. All species have a slender and elongated profile, a long tail, narrow head and pointed snout. The eyes each species have horizontal pupils, shaped like keyholes, which gives Twig snakes binocular vision. Twig snakes are greyish-brown with faint light and dark markings. When threatened, Twig Snakes inflates their throat to display bold black markings between the scales.

The Twig Snake is one of the several back-fanged colubrids whose bite is highly venomous and potentially fatal. The Twig Snake’s venom is hemotoxic, and although the venom’s effects are very slow, and bites are rare, no antivenom has been developed and several fatalities (such as Robert Mertens) have occurred.

The African Twig Snakes are distinctive in appearance and unlikely on that continent to be mistaken for any other snake, if indeed the observer notices them. Preying on lizards, frogs and sometimes birds, they conceal themselves in trees but often at a low enough level to be able to also strike at terrestrial prey, which they may swallow upwards after killing. Their cryptic coloration and apparent ability to freeze or sway gently, as chameleons do, like a twig on a tree (hence the name) makes them hard to spot. Indeed, they may be more abundant in areas than is immediately obvious.

Thelotornis is characterised by a depressed and flat head, keyhole-shaped pupils, and in T. kirtlandii, a projecting canthus rostralis which forms a shallow loreal groove on each side of the head. This allows a certain amount of binocular vision to the snake. In appearance, the head at least is unlikely to be mistaken for any other African snake. Other characteristics include a very long tail and large back fangs. The iris in the species capensis and kirtlandii is yellow, and presumably therefore also in usambaricus.

From Wikipedia, the free encyclopedia.