African Twig Snake

It combines several strategies into one of the most complete disguises of any snake. Its body is extremely thin and elongated, coloured in the exact greys and browns of weathered bark and dead wood and finely marked with lichen-like flecks, so that at rest among branches it reads as just another twig. Beyond simple colour and shape, it behaves like a branch, holding the front third or more of its body extended rigidly and unsupported into the air, sometimes for an hour or more, and swaying it very slightly and irregularly, mimicking a real twig moving in a breeze. This makes it nearly impossible to detect, which serves both to hide it from predators and to let unsuspecting prey approach within striking range.

It is potentially very dangerous, though bites are genuinely rare because the snake is placid, slow to bite, and its rear-set fangs make it hard for it to inject venom into a person accidentally, so most serious bites have involved people deliberately handling the snake. When envenomation does occur, the venom acts on the blood-clotting system, and symptoms including uncontrolled bleeding from the bite site, gums, and internally can be severe and are often delayed by many hours, with fatalities recorded. Critically, no specific antivenom is manufactured for this species, so treatment is limited to supportive care, which is why the twig snake is treated with great caution by herpetologists despite its gentle reputation.

The twig snake has a horizontally elongated pupil shaped like a keyhole or a sideways figure eight, which is uncommon among snakes, and its snout has shallow grooves running along each side toward the eyes. Together these features allow a greater degree of overlap between the fields of view of the two eyes, giving the snake reasonably good binocular vision and therefore good depth perception. For an ambush hunter that must judge exactly when a small, fast lizard or bird has come within reach of a single accurate strike, precise distance estimation is a real advantage, and the eye shape reflects that.

Rather than fleeing quickly or striking, a threatened twig snake typically performs a deliberate warning display. It inflates the front part of its body and neck, stretching the skin so that dark colouring normally hidden between the scales becomes visible, and it protrudes its long, vividly coloured black-and-pink tongue and holds it extended and still, rather than flicking it in and out as snakes normally do. This combination makes the snake look larger and more conspicuous and signals to a potential predator that it has been detected and that the snake is prepared to defend itself, often enough to end the encounter without a bite.