Slithering scales in Bengal
What makes a snake leave its common habitat and move to areas which are not a part of its range? Follow the account of a Saw-scaled viper, found in southern West Bengal.
It was the 23rd of July, 2018. We were searching for birds at the outskirts of Jhargram, West Bengal. We had startdat an early hour in the morning. The rays of the sun had begun to warm the earth after a rainy spell during the night. The entire South West Bengal has laterite soil, and thus the conditions are dry, stony and small rocky mound area, covered with small patches of grasses, small shrubs and bushes as well as big and small boulders.
There was no sign of people or cattle that day in late July, just some old, deserted houses. Suddenly our eyes noticed a movement on a boulder. We approached the boulder very carefully and discovered the source of the movement to be a Saw-scaled viper. The snake was basking in the full force of the sun, a common habit among the species.
The Saw-scaled viper(Echis carinatus) is easily distinguishable from other Indian snakes by triangular head, blunt frontal and absence of shields on the head (basically presence in Elapidae and Colubridae), the broad ventral covering the whole belly and the undivided sub-caudal shields. The color-pattern consists of pale brown ground color, overlaid mid-dorsally with a series of variably colored, but mostly whitish spots, edged with dark brown, and separated by lighter inter-blotch patches. They also may identified by their “Y” type head marks and hissing sound, produced when they rub their body scales in “S” posture. The specimen we had found was approximately 20 cm long and a sub-adult.
The Saw-scaled viper (Echis carinatus), a species of small venomous snakes that inhabit the Middle East and southern Asia to India and Sri Lanka, are characterized by a stout body with a pear-shaped head that is distinct from the neck, vertically elliptical pupils, rough and strongly keeled scales, and a short thin tail. On both sides of the body are several rows of obliquely arranged serrated scales. Adults range in length from 0.3 to 0.9 metre (1 to 3 feet). Echis coloration includes various shades of brown, gray, or orange with darker dorsal blotches and lateral spots.
Saw-scaled vipers move by side-winding locomotion. They are nocturnal, coming out at twilight to hunt for prey, which includes mammals, birds, snakes, lizards, amphibians, and invertebrates such as scorpions and centipedes.
Saw-scaled vipers are small, but their irritability, aggressive nature, and lethal venom make them very dangerous. When alarmed, the Saw-scaled viper will move slowly with its body looped into S-shaped folds. The oblique scales are rubbed against each other to produce a hissing sound, which is a defensive alarm used to warn potential predators. These snakes are, however, quick to strike, and mortality rates for those bitten are high. The fangs of this serpent are remarkably strong, which may help them penetrate and create holes in leather shoes. Saw-scaled vipers inject Hemotoxic venom in their enemies when they bite, which is 5 times as toxic as Cobra and 16 times as toxic as Russel’s viper and is very rapidly absorbed. About 20% of the bites may prove fatal. The poison acts mainly as an anti-coagulant, a destroyer of blood cells and lining of blood vessels.
Saw-scaled viper is one of big four venomous snakes in India that are most common and also responsible for most of the snakebite cases and deaths. Though essentially a dry area snake, it occurs in semi-desert and hilly area or broken scrub country. Although they are distributed throughout mainland India, their presence is rare in Northeastern parts of the sub-continent and West Bengal.It has been recorded as extremely abundant in some parts of the Deccan plateau., There has been no record of this species in southwestern parts of West Bengal in recent past.
Our chance discovery of the Saw-scaled viper in West Midnapur District proves the presence of still a strong biodiversity in this threatened biodiversity zone of India. Major threats to this species are habitat destruction despite the fact that this snake is well adopted to live in ignored lands and rocky terrain. Killing of the viper due to its venom potency and road kills are other major causes.
This is an Joint article by Sayan Dasmahapatra & Kaustav Chakraborty
Read also: Junglimericks: In the Crazy Wilds of India
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