identification of poisonous snakes

1. Identification of Poisonous Snakes
B.Ashok Kumar
Assistant Professor of Zoology
KRK Govt Degree College
Addanki-523201.
9652929696,9441635264
ashokkumarzoology@gmail.com

2. Introduction
2700 species of snakes
Distributed in tropical & sub tropical regions
Absent in New Zealand, Ireland & some
isolated oceanic islands
Only few sps., are poisonous
The bite venomous snake- two marks of fangs

4. Characters to identify poisonous snakes
• Tail
• Ventrals
• Head
• Sub caudals
• Loreal pit
• Supra labials
• Hood
• Infralabials
• Vertebrals
• Neck
• Eyes are to be examined

5. 1.Tail
• Laterally compressed- sea snake- deadly
poisonous
• cylindrical and tapering- may be poisonous
may not be poisonous
• Then ventrals are to be examined

7. 2.Ventrals(Scales on ventral side)
• If the ventrals are small- Non venomous
• If ventrals- broad but not extends fully across
belly- non poisonous
• If the ventrals are broad and extends fully across
belly- May be poisonous/ Non poisonous
• Then the head is to be examined

8. 3.Head & 4.Sub caudals
• Head –triangular & small scales- true vipers-
venomous
• Loreal pit is absent
• Two indian pitless vipers

9. – If sub caudals –two rows-Vipera russellii
– Dorsal surface shows- three rows of large black
rings(chain viper)
– If sub caudals – single row- Echis carinata(saw scaled
viper)- Dorsals are keeled and serrated-An Arrow
mark on the head

10. 5. Loreal Pit
• If the head –coverd by shields- may be venomous/
Non venomous
• Then loreal pit is to be observed
• If loreal pit – in between Nostril & Eye- Pit viper
• Eg: Ancistodon himalayanus,
Lachesis(=Trimerisurus) strigatus

12. Supra labials & Hood
• If the 3rd supra labial touches the eye and
nostril- may be cobra/ coral snake- both
venomous
• If hood is present with spectacle mark
dorsally- Naja naja- small cuneate plate in
between 4th & 5th infralabials. Sub caudals in
two rows

14. Ophiophagus hannah
• Largest poisonous snake
• King cobra
• Hood with transverse stripes
• Sub caudals in single row near cloaca, two
rows in remaining
• Feeds on other snakes

15. Coral snakes
• Hood is absent
• 3rd supra labial touches eye and nostril
• Coral spots on the belly
• Eg: Callophis, Hemibungarus, Micrurus

17. Infralabials & Vertebrals
• If there are four infralabials and 4th
is largest- krait
• In krait mid dorsal scales
(vertebrals) are large and
hexagonal
• Sub caudals in single row
• The venom is more toxic than
cobra
• Eg: Bungarus coerruleus- common
krait- dorsal surface-
bluish/brownish black with white
cross streaks
• Bungarus fasciatus- branded krait-
marked with alternate broad black
yellowish rings

19. Eye
• If the pupil of eye –
vertical, elliptical (cat
like)- venomous
• If the pupil is round
located in the centre
- non venomous(
exception- coral
snake)

20. Snout
• If snout – pointed/sharp triangle shaped-
poisonous
• If snout- round – non poisonous

21. Neck
• If neck is constricted- Poisonous
• If neck is continuous without constriction- non
poisonous

22. Teeth
• Non poisonous- same type(homodont) solid
teeth present on upper and lower jaw
• Poisonous – fangs (maxillary teeth) in upper
jaw- canines- grooved/ hollow

23. Rattle
• If rattle on its tail- poisonous- Rattlesnake
• If rattle is absent- poisonous/ non poisonous

24. Identification of Poisonous Snakes
Sl.No Character Poisonous Snakes Non-Poisonous Snakes
1 Colour Bright coloured Dull except pythons, sand
boa, Anaconda
2 Shape of
head
Long triangular with wide
posterior portion
Narrow and elongated /
round
3 Pupils Cat eyes like with vertical slit
like, elongated pupils except
in cobras
Circular/ round
4 Neck Clear constriction is seen
b/w the head and the neck
No constriction
5 Hood Present in majority but not
conspicuous; highly
developed in cobra absent in
coral snakes, krait, Russel’s
viper..
Absent

25. Identification of Poisonous Snakes
Sl.No Character Poisonous Snakes Non-Poisonous Snakes
6 Tail Abruptly tapered and
cylindrical but in sea
snakes- flat and oar shaped
Long and tapering except in
burrowing snakes. Short and
stumpy in Typlops and
Leptotyplops; very short and
rough in Uropeltis ; short and
blunt in sand boas
7 Head scales Covered by large plate like
shields followed by small
ones
On head are large but in sand
boas head scales are small
8 Dorsal
scales
Small but spinalscales are
larger and hexagonal in
kraits
Dorsals are larger but spinal
scales are not large and
hexagonal
9 Ventral
scales
Usually entire and extend
across the belly. In sea
snakes ventrals are small
and granular as seen on the
dorsal side
Either across the belly
completely (colubrids)or not
(Boa,Uropeltis)

27. Common Non Poisonous Snakes
• (1) Python.
• (2) Ramphotyphlops (common worm or blind snake).
• (3) Ptyas (the rat snake).
• (4) Eryx (Boa, double headed snake ‘Dumuhi’).
• (5) Dendrelaphis (Tree snake).
• (6) Tropidonotus (common pond or grass snake).
• (7) Dryophis (Green whip snake).
• (8) Ahaetulla nasuta (vine snake)
• (9) Eunectes murinus( green anaconda)-Largest snake in
the world-9.5m and 250kgs
Python reticulatus- South east Asia- longer than anaconda-
10m- but more slender