Three species of snake can spit or eject the venom in a fine spray, which is aimed at the eyes of an enemy and projected for distances up to 2.4 m (8 ft). If the venom gets into the eyes, it may cause blindness. The spitting is used only in defense and never to obtain food.
Some cobras can spray their venom for a distance of up to 2.5 meters . This action is called spitting , but it does not evolve puckering the lips and blowing the venom outward . Spitting is a defensive behaviour that has nothing to do with killing prey. Spitting cobras bite and envenomate their prey just as do other venomous snakes.
Two of the spitting-cobra groups are African: -
One group is the African ringhal cobra (Hemachatus haemachatus) , and the second includes the black-necked cobra (Naja nigricollis), the Mozambique spitting cobra (N . mossambica) , the Mozambique red spitting cobra (N . pallida) , and the wEst African spitting cobra (N . katiensis).
The third group is from eastern Asia and includes the golden spitting cobra (Naja sumatrana) of the Malay Peninsula and Sumatra, the Indonesian spitting cobra (N . sputatrix) of southern Indonesia, the common spiting cobra (N . philippinensis) and Samar spitting cobra (N . samarensis) of the Philippines, the Chinese and Indochinese populations of the Asian black cobra (N . atra), and some populations of the widespread Asian monocled cobra (N . kaouthia). These snakes live in areas inhabited by large herbivores that might trample them or large carnivores that might eat them, and thus use their venom defensively.
At close quarters, the spitting cobras have very accurate aim. If the neurotoxic venom reaches the eyes, it is quickly absorbed by the capillaries of the conjunctiva. The venom may cause temporary blindness by irritating the cornea, extensive damage of the cornea can lead to permanent blindness . The venom should be rinsed out of the eye as soon as possible.