Introduction to Genus Echis in Sri Lanka

Saw-Scaled Viper
Saw-Scaled Viper | chamod goonathilake©

Echis Merrem, 1820 is a genus that includes venomous vipers. They are distributed over the dry regions of Africa, the Middle East, India, Sri Lanka and Pakistan. Saw-Scaled Viper (Echis carinatus) is one of the most endangered venomous snakes in Sri Lanka, spreading over a very limited geographical area. We believe that this species of the snake got its name from the sand dunes due to its arid ecosystems and its limited distribution to coastal areas with small sand dunes. Although Saw-Scaled Viper is also found in the Indian subcontinent, the Sri Lankan Saw-Scaled Viper population is smaller in size (length) than the Indian population. This snake species is easily recognizable by its body size and the sound produced by the scales rubbing against each other as a precaution. The body is small but has a strong cylindrical shape. Coarse body covered with scales with clear keel often grey or brown.

The colour pattern consists of the pale buff, greyish, reddish, olive or pale brown ground colour, overlaid middorsal with a range of variably coloured, but mostly whitish spots, edged with dark brown, and separated by lighter inter spot patches. A set of white bows run dorsolaterally. the top of the head features a bird footprint/trident pattern and there’s a faint stripe running from the eye to the angle of the jaw. The belly is white and has a brown dot on each scale. the tail is short

Although primarily a nocturnal terrestrial snake, it is also reported to travel during the day. During the rainy season, most of the adult animals can be seen on small bushes. During the day, they spend time in relatively cool places, such as rocky outcrops and dry pits. Saw-Scaled Vipers have been reported to bury their bodies in sand and remain still with only their heads on the surface. This is an action performed by other snakes of the genus Echis. This tactic can be considered as a measure to avoid being caught by predators and to control body temperature. Saw-Scaled Vipers show sidewinding in the movement of sandy ground.

This is also an example of a Saw-Scaled Vipers adapting to its temperate natural environment. By side winding, only two parts of the body touch the ground. Therefore, no matter how hot the ground is, Saw-Scaled Vipers are capable of moving fast without difficulty. It is a very speculative snake and can attack even with a small obstacle. As soon as he feels threatened, he spins his head forward and moves his body so that his scales intertwine. Due to the relatively serrated position of the keel in the scales in the lateral area of the Saw-Scaled Vipers body, the keel of one scales produce a saw-like sound (“sizzling”) when the keel of the other scales are rubbed together. This is a warning system typical of Echis snakes.

Saw-Scaled Viper | chamod goonathilake©
Echis carinatus | chamod Gunathilake©

Saw-scaled Vipers are live-bearers. At birth, the juveniles are about 8cm in length and 30-50cm in adulthood. Saw-Scaled Vipers feed mainly on small mammals and reptiles such as lizards, and juveniles feed on invertebrates such as insects. It also eats other small snakes and frogs. It is found in thorny bushes and sandy ecosystems along the north, east, northwest, and southeast coasts of Sri Lanka. Saw-scaled Vipers are among the most venomous snakes in the world. However, scientists believe that the venomousness of the Saw-scaled Vipers population in Sri Lanka is less than that of E. carinatus snakes found in the Indian subcontinent and some parts of the Middle East. The venomous composition of Saw-Scaled Vipers contains mainly toxins Haemotoxins that damage the circulatory system and Cytotoxins that damage tissues. Delays in getting the patient to the hospital for proper treatment in the event of a bite can be fatal. Local envenomation of the bite is excessive bleeding from the placenta and swelling around the mouth. Systematic envenomation of the whole body is characterized by delayed internal blood flow due to delayed blood clotting. Because the body is small, the amount of toxins released in a single bite is as small as 12mg, but due to the severity of the poisoning, medical treatment is essential. The lethal dose for humans is around 5mg (as a result of research using Indian Saw-Scaled Vipers populations, it may not be 100% accurate for the population in Sri Lanka). By the end of 2016, the Clodomiro Picado Research Institute in Costa Rica had developed a new antidote to treat Saw-Scaled Vipers bites in Sri Lanka.

No matter how venomous the snake, the Saw-Scaled Vipers also does a silent service to man, helping to maintain the balance of the environment. That is the use of Saw-Scaled Vipers venom to produce Tirofiban, an antiplatelet drug that prevents blood clots from forming in the human body. Killing these snakes indiscriminately due to ignorance and fear is the main threat to their survival. In addition, severe deforestation and nocturnal road accidents can be considered as factors that rapidly reduce the population of this species. The Red Data Report identifies the species as an endangered species (Vulnerable-VU).



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