How to Identify the Sri Lankan Green Pit Viper (Identification Guide)
A venomous arboreal pit viper endemic to Sri Lanka, identified by its bright green body, triangular head, and heat-sensing pits adapted to a life among forest foliage.
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Key identifying features
The Sri Lankan Green Pit Viper (Trimeresurus trigonocephalus) is a venomous arboreal pit viper endemic to Sri Lanka. It is identified by its vivid green coloration that provides camouflage among leaves, a broad triangular head distinct from the neck, and heat-sensing pits located between the eyes and nostrils.
Coloration & pattern
The body is typically bright to yellowish-green, sometimes with a series of faint darker or bluish speckles, crossbands, or a thin lateral stripe running along the body, though patterning is often subtle against the predominantly green background. Males and females may show slightly different shades or markings, with some individuals displaying more pronounced spotting than others. The belly is usually a paler green or yellowish tone.
Head, eyes & scales
The head is large, broad, and triangular, clearly wider than the neck, a hallmark of pit vipers. Heat-sensing pits sit between the eye and nostril on each side of the face. The eyes have vertically elliptical pupils and are often a reddish or golden color, contrasting attractively with the green head. Scales are keeled, giving a slightly rough texture to the body.
Size & body shape
Adults typically reach 50 to 80 cm (20 to 31 inches) in length, with females generally larger and more robust than males. The body is moderately slender with a prehensile tail adapted for gripping branches while climbing through forest vegetation.
Range & habitat where you'll see it
This species is endemic to Sri Lanka, where it inhabits wet zone forests, plantations, and gardens at low to mid elevations. It is arboreal and nocturnal, typically found coiled on branches, shrubs, or low vegetation, relying on its green coloration to blend into foliage.
How to tell it apart from look-alikes
The Sri Lankan Green Pit Viper's bright green body and endemic range help distinguish it from other regional green pit vipers, though close relatives elsewhere in South Asia can appear similar; range is a key clue since this species is found only in Sri Lanka. Its triangular head, heat-sensing pits, and vertical pupils separate it from harmless green vine snakes and other non-venomous green arboreal species, which have narrower heads, round pupils, and smooth scales. Subtle differences in eye color and speckling pattern can help separate males from females.
Frequently asked questions
Where is the Sri Lankan Green Pit Viper found?
It is endemic to Sri Lanka, found in wet zone forests, plantations, and gardens at low to mid elevations.
What color is this snake?
It is bright to yellowish-green, sometimes with faint darker speckles or crossbands, aiding camouflage among leaves.
How is it distinguished from harmless green snakes?
By its broad triangular head, heat-sensing pits, vertically elliptical pupils, and keeled scales, none of which harmless green vine snakes possess.
How large does it grow?
Adults typically reach 50 to 80 cm (20 to 31 inches), with females usually larger than males.
Is this species arboreal?
Yes, it is arboreal with a prehensile tail, typically found coiled on branches and low vegetation.