Vipers are a very distinct group of snakes, all poisonous. The American rattlesnake belongs to this group. In Malaysia, species of viper belong to the Pit-vipers, distinguished by the presence of a deep pit on each side of the head, between eye and nostril. This is a thermo-sensitive organ, designed to detect heat in a very small amount; it enables the snake to find warm-blooded prey in complete darkness. The bite is not dangerous to human life and usually results in more or less acute pain and swelling around the bitten part. The commonest species, Wagler’s Pit-Viper, is the species kept in the Snake Temple in Penang. (Source: Malayan Animal Life)
This one came awandering and was released after subjected to curious inspection by us.