You'll notice that the places that you see blue veins are in areas where the skin is thin and the blood vessel underneath is pushing up on it stretching the skin over it. Light hitting the dark color of the vein underneath the skin, in combination with the skin itself is what causes it to appear blue in these areas.
Common krait. The common krait (Bungarus caeruleus), also known as Indian krait or blue krait) is a species of venomous snake of the genus Bungarus found in the jungles of the Indian subcontinent. It is a member of the big four species, inflicting the most snakebites on humans in India.
Tiger snakes are highly venomous as well. They eat other snakes and medium sized rodents. Tiger snakes are of a large variety and so are their characters. Biting is a last resort for tiger snakes (exception: the black Tiger snake).They either make a swift getaway or rely on several minutes of intimidation. 3. King kobras are the largest of all venomous snakes in the world. They are highly territorial & not very gentle. they only feed on other snakes so their venom has to be strong. They are also immune to the venom of other local snakes.   4. Common kraits are highly venomous (as usual).