Part of the show Science Questions and Answers
Penny McNeil asked:
Are snakes susceptible to their own venoms?
Helen - Thatís a great question. There are two things to consider. That is, they arenít susceptible to their own venom in their own fangs, because they donít kill themselves every time they make some venom. Thatís pretty cool but also quite easy to understand.
We also have poisonous chemicals inside our bodies that donít kill us. Theyíre kept in certain areas, for example, our pancreas contains a deadly cocktail of enzymes. If your pancreas bursts and they all come out then that can really spell a big problem for you and you start digesting yourself from the inside. But because these enzymes are kept in certain organs that are lined with cells that arenít susceptible to those enzymes, then youíre okay. And once it goes into your digestive tract then youíre okay, because the tissue there has protection to help it to cope with it.
This is also why if a snake happens to swallow some of its own venom it will be okay, because the venom is made of protein. So the venom will break down when it gets into the digestive juices in the stomach.
The other question is what if a snake accidentally bit itself or if another snake bit it? The answer seems to be yes, they are susceptible to their own venom. If itís injected into their system they can be susceptible to it, but some scientists have also found anti-venom inside snakes. They can develop their own anti-venoms (antibodies) to their own venom, but we donít quite yet know how that happens. It could be that they have a low level of exposure. Accidentally biting themselves occasionally, as you do?
You can imagine thereís some selective pressure for a snake to evolve, maybe not from itself, but perhaps from its mate or something.
Chris - A good corollary is spiders, isnít it? We know that spiders are vulnerable to their own toxins. A female can bite the male and kill the male with their venom. I suppose the same could be true for snakes because these venoms are proteins that have been injected into the body.
There are humoral factors in the snake's blood that protect it from its own toxins - but this is answered in full by TNS here:
Great article, however this article in the National Geographic suggests otherwise (particularly for cobras that use neurotoxins). Does the above only refer to vipers and large doses of venom? http://news.nationalgeographic.com/news/2004/02/0220_040220_TVcobra.html Matthew Moroney, Thu, 13th Nov 2014