Ninety-six species of snakes are known to inhabit Sri Lanka. Of the venomous terrestrial snakes of the country, only four species, namely Russell’s viper, cobra, common krait and the Merrem’s hump-nosed viper are responsible for the majority of deaths due to snake bite envenoming. However, non-venomous and mildly venomous snakes are responsible for the significant number of hospital admissions. Venomous snake bite without envenoming the victim can also be seen. Deadly venomous snakes such as kraits, cobra, Russell’s viper and the hump-nosed viper are common in human habitations and agricultural fields.
The venomous snake has a fang apparatus and venom gland. Non-venomous snake do not have fangs but possesses teeth. Based on the position and presence of fangs, the snakes are broadly classified into four groups.
1) Aglypha (No fangs) – Mainly non-venomous snakes
2) Opisthoglypha (posterior fangs) – Mildly venomous snakes such as Colubrid snakes.
3) Proteroglypha (anterior grooved non-mobile fangs) – Venomous snake such as cobra, krait, coral snake and sea snakes.
4) Solenoglypha (Canalised and mobile anterior fangs) – Venomous snakes such as vipers including pit vipers.
The aglyphous snake has teeth and powerful jaws but does not cause any envenoming. The opisthoglyphous snake has short back- fangs and Duvernoy’s glands. It can hardly produce any envenoming in man.