Poisonous snakes : Cobra, Krait, Vipers, Sea Snakes and Poison Apparatus of a Snake

Poisonous snakes : Cobra, Krait, Vipers, Sea Snakes and Poison Apparatus of a Snake

Poisonous snakes

Indian poisonous snakes are the cobras, the kraits, the vipers and the sea snakes. These can be distinguisted from the non poisonous by the tail, the arrangement and size of scales, plates and shields found over the body.

Cobra : It is well known all over India. When provoked it raises its head and expand the skin of the neck region in the form of a characteristic hood. The hood may bear a spectacle mark. Such cobras are called two ringed or spectacled forms. In others there is a oval spot surrounded by an ellipse. These are known as the one ringed or monocled variety. They are found in Bengal. In still others there is no mark on the hood. Only two species of cobra are found in India. They are Naja naja (Indian cobra) and Ophiophagus hannah (king cobra).

Krait : These are common poisonous snakes of India. There are two com-mon Indian kraits. They are the common krait (Bungarus coeruleus) and the banded krait (B. fasciatus).

Vipers : There are two classes of vipers. Some have a distinct pit on the sides of the head between the nostril and the eye in the region called 'lore'. These are called pit vipers. The other one is the pitless viper.Vipers are vivipa-rous in nature.

The vipers have movable upper jaw, so that the fangs when not in use can be folded backwards. It gets erected with the opening of the mouth while inflict-ing injury. It produces a loud hissing sound by expelling air through nostrils.

Pitless Viper - Vipera russellir (Russell's viper) Echis carinata (The little Indian viper).

Pit viper - Trimeresurus sp

Sea Snakes : Sea snakes can always be distinguished from other snakes by their laterally compressed tails. This is an adaptation to their life in the sea. All sea snakes are highly poisonous.

Eg. Hydrophis sp Enhydrina sp

Poison Apparatus of a Snake

The poisonous snake possesses a poison apparatus comprising of a pair of poison glands, a pair of poison ducts and a pair of fangs. The poison glands are situated on either side of the upper jaw below and behind eyes. They are specialized salivary glands. A duct carries the venom secreted from each gland to the fang. A fang is meant for injecting the venom into the body of the prey. Fangs are specialized teeth of the upper jaw which are tubular or grooved.

Biting mechanism in Cobra

Cobra is not an aggressive snake. When disturbed, it attempts to escape. When the snake attacks, the mouth opens by lowering the lower jaw. This makes the fangs to be erect to penetrate the muscles of the victim. When the mouth is closed the poison glands are pressed. The venom thus reaches the fangs and is injected into the body of the victim. This whole process takes place in no time.

Snake Venom

There are two types of snake venoms. One type acts mainly on the nervous system (neurotoxic). It affects the optic nerves (causing blindness) or the phrenic nerve of the diaphragm (causing paralysis of respiration). The other type is haemolytic. It breaks down the red blood corpuscles and blood vessels and produces extensive extravasation of blood into the tissue spaces.