How Does Venom Work?
After this quick introduction to the venomous animals, I would like to ask: Why do they have venoms, and how does that venom work? There are venomous and poisonous species basically in all kinds of ecosystems, and they are distributed everywhere in the animal kingdom.
The three most important and basic reasons that animals have venom are prey-immobilization, predigestion and defense. Of course, poisonous animals, which have toxin distributed throughout their bodies, don't have all these functions. With venomous snakes, venomous lizards and scorpions, for example, all three functions are achieved by the venoms of each animal.
Zoltan Takacs | This profile view of a snake skull shows the fangs, which are hidden in this view behind the lower jaw bone, and the replacement fangs behind them. If a fang breaks off after biting into an animal, the replacement fang moves forward and replaces the fang that was broken.The smaller teeth in the back of the jaw are used to hold prey in the mouth. |
The venoms of snakes are produced, or secreted, in the main venom gland, which works like a modified salivary gland, located in both sides of the head. That's where the venom is stored. When the snake bites, the venom travels through the primary duct across the accessory venom gland, then via the secondary duct to the base of the functional fang, which has a long tunnel starting at the base of the fang and ending at the tip of the fang. That functional fang is responsible for injecting the venom into the body of the victim or the prey animal.
What happens if a snake bites into a rat and the rat jumps and the functional fang accidentally breaks off into the body of the rat? Then the most advanced replacement fang will take its place, so the snake will not be left without a working fang and will remain capable of delivering more bites even after the functional fang is broken off.
If you look at an actual skull of a venomous snake, like a rattlesnake, you can clearly see the functional fang sitting on the upper jaw. The growing replacement fangs are folded just behind the functional fang, and on the bottom and top of the mouth are the teeth, which have nothing to do with venom injection. These teeth just serve to grab the prey and help to swallow it.
Venomous animals, like the snakes, have a special apparatus that produces the venom and injects it in the body of the animal.
Why don't venomous animals poison themselves?
If snakes and all of these venomous animals have very potent toxin, what happens if the animal bites itself? Snakes and other venomous animals also have to have the neuromuscular junction. From an evolutionary perspective, there is pressure on the snake to have a toxin that works against a wide variety of animals. This is because if you have a toxin that is potent against so many taxa, then you have many more choices of food sources and you have a much more potent weapon to defend yourself. There were some papers published in the 1970s that explain why some groups of venomous snakes are resistant to their venoms. These papers showed that the vipers, including the North American pit vipers, have some humoral factors in their blood, in their circulation, which will neutralize the venom once it gets into the blood, and there won't be any problem. Nobody has looked at if cobras use the same mechanism, so I began a research project to look at why cobras do not poison themselves and am hoping to publish the results in the near future. |
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