A large adder with adults reaching 1,2 – 1,4 meters in length in SA, but this snake grows to 1,8m in East Africa. These large individuals would have fangs up to 50 mm in length. The head is very broad and covered with small keeled scales and distinct from the neck. The tail is very short, especially that of the female. The colour is a mixture of purple, pinks, browns and white or cream. The head is normally creamy white on top and the side of the head has two black triangles, one below the eye and one that runs to the angle of the jaw. There are 10 – 12 rectangular white markings on the back. The sides look like butterfly wings have been pasted onto the snake, being very colourful, and there are half-moon patterns of purple on the sides. The ventral part is a uniform dirty creamy colour with darker blotches. The scales are heavily keeled and in 33-46 rows at midbody.
Hinged front fangs normally 20 – 25 mm in 1,2 to 1,4 m individuals, but this species of snake holds the world record for fang length. A very large snake 1,8m in length from Kenya, had fangs of 50mm in length.
The venom is cytotoxic, neurotoxic and haemotoxic but the effect of a bite is mainly cytotoxic in its action in man, with the normal disfiguring result at the bite area that is associated with this type of venom. The neurotoxin is specific in its interference with heart muscle conductivity and can cause cardiac arrhythmias so it is better known as a cardio toxin that causes atrial arrhythmia; prolonged QT interval and T wave inversion. The haemotoxic venom also inhibits platelet aggregation and converts fibrinogen to fibrin causes a DIC condition and the victim can bleed to death. The LD50 in mice is less that of the puff adder; however the venom yield is 500 – 900 mg of venom, with an average yield is 600mg. The combination of large fangs with large quantity of venom would make for a far more serious bite than that of the puff adder. Collapse within 15 minutes has been recorded after this snake’s bite.
This snake is rare in South Africa. It is found from St. Lucia on the KZN coast, north into Mozambique and eastern Zimbabwe. Further north into Zambia, Angola, Zaire, Congo and countries in east, central Africa.
Inhabits permanent rain forests that would not be subject to high fluctuations in temperatures from season to season.
This large adder is potentially very deadly, but has a mild disposition and rarely bites, even when pressed to do so. This is a good thing as a bite is very serious and a medical emergency. Few bites recorded throughout Africa. Most bites have been recorded to snake handlers, with mixed results from mild to very serious. In one case the victim was bitten when he wanted to remove the water dish from the snake’s cage. This was probably a feeding response, and the victim collapsed 15 minutes after the bite. Large amounts of polyvalent antivenom injected intravenously, saved the victim’s life. There was some scarring at the bite site in this case. The main activity is at night, when the snake will emerge from under leaf litter on the forest floor and move off to hunt or find a suitable spot to ambush prey that consists mainly of rodent and ground living birds. In St. Lucia these snakes move from the forest to clearings in the forest that are covered with high grass where its favorite prey, large vlei rats and wood rats are found. Many of these snakes get killed by road traffic when they cross roads. They are also killed on sight by African hunters who will then eat these snakes. The meat is highly favoured by many African hunters.