Vipers are venomous snakes belonging to the Viperidae family (consisting of roughly 150 species). They are characterised by long erectile fangs, which are folded back when not in use. They also have triangle-shaped heads with a distinctly narrower neck. The broad areas of the head house the venom glands. Their eyes have irises like those of a cat. Being 0.3–3 m long, vipers feed on small animals, which are injected with venom and then followed until they die.
