Russell's Viper

Fascinating facts about the Russell's Viper

• Imagine a snake that can inject enough poison to kill a human with just 40 mg of venom – that’s the lethal dose of Russell’s viper, while the snake can deliver up to 250 mg in a single bite. Its venom toxicity in mice is measured at just 0.133 mg per kilogram intravenously, making it one of the deadliest snake venoms known. This potency explains why a bite from this species can cause rapid swelling, bleeding, and even kidney failure within days.
• A female Russell's viper can carry a litter of up to 75 young, while typical litters range from 20 to 40, and the newborns are already 215 mm long.
• A single adult Russell’s viper can grow to 166 cm in total length, but most mainland individuals average about 120 cm, with island snakes being a bit shorter. Its tail makes up only about 14 % of that length, roughly the size of a standard ruler. These compact dimensions help it slip through grass and scrub where it hunts rodents, its primary prey.
• Even without the heat-sensing pits of pit vipers, this species can still detect thermal cues through nerve endings in a supranasal sac, allowing it to hunt warm-blooded rodents at night. Its nocturnal foraging habit switches to daytime activity when the weather turns cool.
• Despite its reputation, the snake’s defensive display includes a loud hiss louder than any other snake and a rapid strike that can lift its body off the ground. When threatened, it forms an S-shaped loop and may hang on its victim for several seconds. These dramatic behaviors have led to myths that the viper “chases” humans, when in fact it only attacks when provoked.

About the Russell's Viper

The Russell's viper, Daboia russelii, is a stout, triangular-headed viper whose flattened crown is cloaked in irregular, fragmented scales and its body bears a striking mosaic of deep yellow, tan or brown ground punctuated by three rows of dark brown spots, each ringed in black and edged with white or yellow. Adults average about 120 cm in mainland Asia, with a maximum length of 166 cm, and their short tail makes up roughly 14 % of that length. Their fangs, up to 16.5 mm long, can inject a venom load of up to 268 mg, enough to deliver a lethal dose to a human in a single bite. Though primarily nocturnal, they become diurnal in cooler weather, moving sluggishly across open grasslands, scrub jungles, farmland and even densely populated villages where rodents, their favourite prey, abound. Juveniles are more nervous, often crepuscular, and will even cannibalize their kin, while adults specialize on rodents but will also take small reptiles, crabs, scorpions and other arthropods. A surprising trait is their ability to sense thermal cues despite lacking the classic pit organs of true pit vipers, hinting at a hidden heat-sensitive structure in the supranasal sac that researchers are still deciphering. In the lowlands and coastal plains of India, Sri Lanka, Bangladesh, Nepal and Pakistan, the Russell's viper thrives in open, grassy or bushy habitats, shunning dense forests and humid swamps. It is abundant in Punjab, the West Coast, Karnataka and up to Bengal, yet scarce in the Ganges valley and Assam. Its tolerance for human-altered landscapes brings it into frequent contact with people, making those who work outdoors in agricultural fields or rural settlements especially vulnerable to its extremely painful bite. Though often mischaracterized as a “chaser,” the viper typically strikes only when provoked, delivering a rapid, forceful bite that can even lift the snake off the ground. Its presence in urbanized countryside underscores a complex coexistence where the very rodents that sustain it also draw it into the orbit of human activity.

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