Poison Apparatus In Snakes – Zoology Notes – For W.B.C.S. Examination.

সাপের মধ্যে বিষ উপাদান – প্রাণিবিদ্যা নোট – WBCS পরীক্ষা।

Nature of Venom

It is a kind of highly evolved saliva which the snake uses to both kill as well as digest its prey. There are two kinds of snake venom. One affects the nerves (the venom of the Cobra and Krait), the other affects blood (that of the Vipers).Continue Reading Poison Apparatus In Snakes – Zoology Notes – For W.B.C.S. Examination.

1. Snake venom is a clear, transparent, pale yellow or straw-coloured fluid having a specific gravity of 1.03-1.07.

2. The pH of the venom varies in diffe­rent species, e.g. in Russell’s viper pH is 5.8 while that of cobra’s venom is 6.6.

3. It is protein in nature containing many enzymes, viz. Proteinase, Hyaluronidase, L-Arginine hydrolases, Transaminase, L-Amino acid oxidase, Phospholipase-A, B and C, Phosphodiesterase, Cholinesterase, Ribonuclease, Deoxyribonuclease, Alkaline phosphatase, Acid phosphatase, Exopeptidases etc. The composition of venom varies from species to species.

4. Most snake venoms are tasteless but cobra venom’s taste is slightly bitter.

5. It is acidic in reaction and soluble in water and glycerine.

6. It is destroyed by coagulating agents like KMnO₄, AgNO₃, as well as alcohol and strong alkalies like NaOH and KOH etc.

7. The venom also contains metals like zinc (Zn), sulphur (S), copper (Cu) etc.

8. Venom contains several active non- enzymatic proteins having at least two or three peptides.

9. Venom is thermolabile.

Effects of Poison:

Venom is generally introduced into the subcutaneous tissue. It then reaches the general circulation. When introduced directly into the vein the effect is instantaneous. The venom of different snakes acts differently.

(a) Cobra poison:

The effects are observed within half an hour. Symptoms are giddiness, high pulse rate, extreme salivation, partial paralysis of tongue and larynx, vomiting and contraction of pupil. The eyes remain sensitive to light and consciousness remains undistur­bed. Respiration is shallow, which ultimately ceases and death follows. Cobra venom is a neurotoxin.

(b) Viper poison:

The effects are observed within a quarter of an hour. Symptoms are swelling of the wounded region, discoloura­tion due to extravasation, acute burning pain, pupil dilatation, high pulse rate, profuse vomiting and watery discharge from rectum. Eyes lose sensitivity to light and consciousness is affected. Extravasation becomes extensive, swelling spreads and death occurs. Viper venom is haemo-toxic.

(c) Krait poison:

Kraits are highly poisonous but the absence of local pain, swelling, oozing or bleeding raise doubt of krait bite in the first hour. Even fang marks do not reveal any visible spot. Symptoms are very much similar with the signs of neurotoxicity of cobras.

Anti-Snake Venom Serum:

In India anti-snake venom serum is prepared at the Hoffkine Institute, Mumbai, and Central Research Institute, Kasauli, Himachal Pradesh. At Hoffkine, anti-venom is prepared by immunizing horses. A mixture of venom of four common poisonous snakes (Cobra, Naja naja; Common Krait, Bungarus caeruleus; Russell’s viper, Vipera russelli and Saw scaled viper, Echis carinatus) is injected into horse’s body and the dose is increased gradually. When the horse acquires a certain level of immunity, the plasma is collected by drawing blood from the body.

After collection, it is packed in 10 ml doses. Anti-venom of Banded krait, King cobra and Sea snake is not produced in India. Nearest source of anti-venom of Banded Krait and King cobra is the Queen Saovabha Institute, Bangkok, Thailand.

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