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.
The king cobra (Ophiophagus hannah) is an elapid found predominantly in forests from India through Southeast Asia. This species is the world's longest venomous snake, with a length up to 18.5 to 18.8 ft (5.6 to 5.7 m).his is akin to the human sense of smell. When the scent of a meal is detected, the snake flicks its tongue to gauge the prey's location (the twin forks of the tongue acting in stereo); it also uses its keen eyesight; king cobras are able to detect moving prey almost 100 m (330 ft) away.