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Did Venom Strength Evolve to fit Habitat

orchidspider Oct 25, 2008 09:54 PM

I have long thought about a theory of mine that snake venom evolved in strength to fit its habitat and that some snakes that live in areas of more rain tend to have a weaker venom per species than those snakes that live in more arid habitats. For example a woodland living variety of the copperhead envenoms its prey. The prey staggers off to die, leaving the snake to have to use its smell and taste to follow the prey's scent and taste to find it and then eat it. This works fine if the snake lives in woodland where presumably there is moisture on the ground to hold the scent and taste particles that the prey leaves behind. However, in a desert environment, if the prey staggers off to die, its scent and taste particles have a higher risk of being destroyed by the area's heat. Thus the desert animal has a higher risk of "losing" its food, than a woodland snake might, who can follow the scent trail easier since it has been kept fresh longer with the moisture of the forest floor.

The desert snake in order to prevent the animal from getting lost would need to have a stronger venom to immobilize the prey faster so to reduce the chance of losing it. Hence you have the Mohave rattlesnake having a stronger venom then supposedly a Canebrake rattlesnake would. Similarly, a sea snake needs to have VERY strong venom so it can immobilize its prey instantly so that it does not wriggle away in the sea, making its recovery almost impossible. By the same token a western copperhead would have to have developed a slightly stronger venom to help it find its food faster before the arid heat destroys its preys scent than a southern woodland dwelling copperhead.

Any thoughts? This idea has always made sense to me, and I was wondering what you all might think?
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Replies (1)

TJP Oct 25, 2008 11:55 PM

I would say it's more because the amount of prey items are much less in arid environments. Not so much the chance of losing prey with scent, but rather not finding prey as often and needing a more potent venom to make sure the chance isn't lost.
I wouldn't use the canebrake vs mojave as an example. It's been shown that neuro population cane's have an extremely virulent venom (I'd put them at the top of the list as far as potency goes in the US). Probably due to an immunity to certain animals they feed off of, much like what's happened with sopac's that have developed a different blend of venom. Evolution for different reasons.

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