There are over 500 species of venomous snakes, distributed worldwide grouped into two main categories: rear-fanged and front-fanged.
Both types have hollow fangs with a cavity running down most of its length. These fangs work like hypodermic needles. Venom from the venom gland enters the snake’s fangs through the venom duct and travels down the hollow canal in the snake’s fangs when the snake opens its mouth. The venom is then injected into the victim through its incredibly sharp, pointed fang tip orifices (openings) when the snake bites down. When biting, a front-fanged snake merely strikes, ejecting the veonom the moment the fangs penetrate the skin, then immediately letting go. While the rear-fanged species actually close their jaws like a dog and hold the prey firmly for a considerable amount of time.
Some species of cobra, commonly called “spitting cobras”, can actually shoot venom from their mouths accurately at a distance of about 4 to 8 feet. Another species of snake, the Rinkhals Cobra, can also spit venom. It is not actually a cobra, but is closely related to them.
Spitting snakes have modified fangs. Inside the fangs are channels which make a 90-degree bend in the lower front of each fang. When these snakes are threatened, the muscles of the venom gland squeeze the venom sack, projecting the venom forward while air expelled from the snake’s lung blows or sprays the venom at its intended victim with the velocity equivalent to that of a water pistol.
Spitting snakes can spit 30 to 40 times in succession and still deliver a lethal bite. Spitting is only used for self-defense against larger animals and humans, not for killing its prey. The snake aims for the eyes of a perceived threat where a direct hit can cause temporary shock and blindness by severely inflaming the cornea and conjunctiva. If left untreated, the blindness could become permanent. To treat, flush the eyes out with plenty of milk. If milk is not available, water will work. In an emergency, urine is an acceptable treatment. Venom on the skin isn’t dangerous, but open wounds could possibly become envenomated.
The size of the snake’s venom gland, venom toxicity, size of the fangs and the size of the fang openings determine how toxic the venom is. Most rear-fanged snakes deliver small amounts of venom slowly and therefore are not a major health threat to humans because their fangs and fang openings are small, and they generally have small venom glands. However, there are notable exceptions, such as the African boomslang which has been responsible for human fatalities. Front-fanged snakes are the most common and recognizable venomous snakes. These snakes are responsible for human fatalities world-wide because their fangs and fang openings are larger and their venom glands are generally larger, as well.