Interesting Facts: The common name, "pit vipers", come from the deep pit between the eye and the nostril on each side of the head. These sensory organs can detect temperature differences of as little as 0.003 degree celsius. This capability enable the vipers to accurately locate and strike warm-blooded prey even on pitch-dark nights.

Highly venomous.
Size: About 1 m
Diet: Small vertebrates
Activity: Primary nocturnal and arboreal.
Habitat: Forested area, mangroves

http://www.wildsingapore.per.sg/discovery/factsheet/snakewagler.htm