Which are the poisonous snakes in the world ?

Scientists have studied about 2400 varieties of snakes. Of them only about 200 are poisonous. In India only 4 of around 200 species are found to be poisonous. They are the cobra, krait, saw scale viper and Russell's viper.
Some of the poisonous snakes in other parts of the world are the rattlesnake, copperhead, cotton mouth moccasin, water moccasin, Eastern diamond back, Harlequin snake and coral snake.

Snakes have poison glands located on both sides of the head, a little below their eyes. They have two fangs on their upper jaw, which have holes. Poison passes from the poison glands to the Snake fangs through a tube.
It is easy enough to identify poisonous snakes. The cobra with its hooded head is easily distinguished. Their hoods have 'V shaped signs on them. The kraits have white stripes on their back. The stripes are sharp towards the tail and faint towards the head. The vipers are dark brown and have diamond shape on their back.
Snakes generally do not attack unless provoked. Always take care when walking through thick high grass. Never step on dry logs or mounds of dry leaves. A snake might be resting under it. Again, never push your hand or foot inside a hole in a ground or in a tree. It could be a snake' nest. When walking in high grass take a long, strong stick and keep tapping it a few feet in front of you. The vibrations caused by the stick on the ground frightens away the snake.
Some snakes are not poisonous but yet are dangerous. The python, anaconda and the common boa squeeze and crush the body of the victim and then swallow it whole. The stomach of these snakes produce powerful digestive juices that can break down even big bones of the victim.