Identification key for poisonous and non poisonous snakes

 Most of the Indian snakes are non-poisonous and harmless organisms. Out of 330 Indian species only 69 are poisonous comprising 40 species of land  snakes and 29 species of sea snakes. The poisonous snakes have a poison apparatus in head and a pair of larger teeth or fangs in upper jaw. When they bite, there may be two large circular punctures made by the fangs on the skin of the victim. But non-poisonous snakes have neither poison apparatus nor fangs. When they bite, they leave  many small pricks only. Some of the mostcommon Indian poisonous snakes are cobras,kraits, pitvipers, vipers and sea snakes. It is easy to distinguish them from non-poisonous ones on the basis of the shape of their tails and the size and arrangement of scales and shields on their body. A simple and workable key for identification is given here

1. Tail

(a) Tail laterally compressed, oar-like -poisonous  Sea snakes  Hydrophis, Enhydrina

             (b) Tail cylindrical, tapering Poisonous or nonpoisonous Land snakes-Examine further

2. Belly scalesor ventrals

              (a) Belly scales small, continuous with dorsals- Non-poisonous

             (c) Ventrals not fully broad to cover belly- Non-poisonous Pythons

(c) Ventrals broad, fully covering belly Examine further

3. Head scales,loreal pit and  sub-caudals

(a) Head scales small. Head triangular. No loreal pit -Poisonous Pitless vipers

                             (i) Subcaudals double -poisonous-Viperu russelli

   (ii) Subcaudals single-poisonous- Echis carinata

(b) Head scales small. A loreal pit present between nostril and eye -Poisonous Pit vipers

(d) Head with large shields. No loreal pit -Examine further 

4. Vertebral 4th infratabial, 3rd supralabia

(a) Vertebrals enlarged, hexagonal 4th infra-labial largest-Poisonous Krait. Bungarus

(b) Vertebrals not enlarged. 3rd supra-labial touches eye and nostril - Poisonous

(i) Neck with a hood and spectacle mark Cobra, Naja

 (ii) Hood absent. Coral spots on belly Coral snakes. Calbphis

 (c) No such characters - Nonpoisonous