Appearance''H. hypnale'' grows to an average of 30–45 cm in total length. The Armed Forces Pest Management Board states 0.4-0.6 m in total length.
Its build is that of a typical viperid with a stout body and a wide head. The snout is pointed and turned upwards, ending in a hump. The frontal, supraoculars, and parietal shields are large, but those on the snout are small and irregular.
The color pattern is grayish with heavy brown mottling, overlaid with a double row of large dark spots. The belly is brownish or yellowish with dark mottling. The tip of the tail is yellow or reddish.
NamingHump-nosed viper, Merrem's hump-nosed viper, hump-nosed pit viper, Oriental hump-nosed viper, hump-nosed pitviper, ''polon thelissa-පොලොන් තෙලිස්සා'' & ''kunakatuwa-කුණකටුවා'' , ''churutta'' .
Behavior''H. hypnale'' is active during early morning and night. It spends the day in leaf litter and thick bushes. This species can be found on the stream side basking during the sunrise. Although it is a slow mover, it is capable of fast strikes. It has an irritable disposition and will vibrate its tail when annoyed, a behavior it has in common with other pit vipers, especially rattlesnakes of the genera ''Crotalus'' and ''Sistrurus''. It has been described as nocturnal, terrestrial, and aggressive when disturbed.
HabitatFound in dense jungle and coffee plantations in hilly areas.
ReproductionAdult females bear live young from March through July. Brood size ranges from 4 to 17, and the newborns are 13-14.5 cm long.
DefenseBites from this species, although previously thought to be innocuous, are now known to cause serious complications such as coagulopathy and acute renal failure . If not treated within a few hours, bites can potentially be fatal for human beings.
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