Overview
The Keeled Slug-eating Snake (Pareas carinatostriatus) is a slender, arboreal colubrid specialized in hunting land snails and slugs in the montane rainforests of Indochina. Famous among evolutionary biologists for asymmetrical jaw structures that match the coiling direction of terrestrial snail shells, this harmless nocturnal snake navigates humid tree branches with calm, deliberate precision.
Biology and Physical Characteristics
Pareas carinatostriatus possesses a slender, strongly compressed body covered in distinctly keeled dorsal scales. Its coloration is a handsome blend of fawn, cinnamon-brown, or ochre, accented by thin dark-brown vertical streaks and a characteristic dark postocular stripe extending from its large, copper-red eyes to the jaw angle. Its head is distinctly broader than the slender neck, equipped with a shortened, blunt snout. Its lower jaw features asymmetrical dentition with more teeth on the right mandible than the left, an adaptation designed to extract right-handed (dextral) snails from their coiled shells.
Behavior and Ecology
Nocturnal and semi-arboreal, the keeled slug-eating snake awakens at dusk when forest humidity peaks and terrestrial mollusks begin moving. It stalks mossy branches, rock ledges, and broad leaves, detecting slime trails with its tongue. Upon finding a snail, it strikes swiftly, inserting its mandibles into the shell opening and using its asymmetrical teeth in an alternating sawing motion to extract the snail’s soft body whole in a matter of seconds. During the day, it sleeps coiled within dense clusters of hanging epiphytes.
Conservation and Human Impact
Evaluated as Least Concern by the IUCN, Pareas carinatostriatus remains relatively widespread across protected montane tracts in northern Indochina. While localized deforestation and agricultural clearing affect unprotected lower-elevation foothills, substantial populations persist within established national parks like Tam Dao and Pu Mat in Vietnam and Doi Inthanon in Thailand.
Interesting Factoid
The jaw of the keeled slug-eating snake has evolved an asymmetrical count of teeth—having significantly more teeth on its right side—specifically engineered to extract right-spiraling snail shells with ease!
Last updated: October 2026