Poisonous snakes...?

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Chris Smith
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Poisonous snakes...?

Post by Chris Smith »

All,

I recall someone posting a genus of snake whose members are poisonous (actually poisonous). Can anyone remind me of the name?

Thanks,
Chis
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Brian Folt
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Re: Poisonous snakes...?

Post by Brian Folt »

Thamnophis, Rhabdophis are two examples. The topic of poison sequestration in vertebrates was recently reviewed by Al Savitzky and friends here:

Savitzky, A. H., A. Mori, D. a Hutchinson, R. a Saporito, G. M. Burghardt, H. B. Lillywhite, and J. Meinwald. 2012. Sequestered defensive toxins in tetrapod vertebrates: principles, patterns, and prospects for future studies. Chemoecology 22:141–158.
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DracoRJC
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Re: Poisonous snakes...?

Post by DracoRJC »

Brian Folt wrote:Thamnophis, Rhabdophis are two examples. The topic of poison sequestration in vertebrates was recently reviewed by Al Savitzky and friends here:

Savitzky, A. H., A. Mori, D. a Hutchinson, R. a Saporito, G. M. Burghardt, H. B. Lillywhite, and J. Meinwald. 2012. Sequestered defensive toxins in tetrapod vertebrates: principles, patterns, and prospects for future studies. Chemoecology 22:141–158.
So thats what Savitzky is up to these days...
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Ruxs
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Re: Poisonous snakes...?

Post by Ruxs »

Rhabdophis subminiatus is probably the best known out of the Poisonous/Venomous snakes. The snake collects poison from poisonous frogs and toads that it eats. This poison can be secreted by arching of the neck or other pressure to the nuchal area.

I have never witnessed Rhabdophis subminiatus helleri, the subspecies found in my area, try to release the poison, but I never handle them roughly, could that make a difference?

Just some stuff off the top of my head. Google it if you want to find out more, but I'm sure someone a little more knowledgable on this topic can elaborate... ...Kevin Messenger, I'm looking at you!
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Kevin Messenger
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Re: Poisonous snakes...?

Post by Kevin Messenger »

yeah, there is video (and photos of course) of the whole thing in the post I made yesterday.

But there are 3 genera that are classified as "poisonous" - Rhabdophis, Macropisthodon, and Blanophis.

Of Rhabdophis, 21 species, 4 supposedly lack the poison glands (though I think it is more like 3), 6 are unknown, the rest have them.

Of the 4 species of Macropisthodon, 3 are poisonous, 1 lacks the glands.

Blanophis is a monotypic genus, and so it's only member is poisonous.

Only one species has been studied, the island populations of what was once R. tigrinus. The tigrinus group is being split. I don't know if the Japanese population will retain the name tigrinus, or if it will be something different. Mainland tigrinus have not been studied, nor any other member (aside from gross anatomy, which is how they can say "this one has the glands, this one lacks the glands").

Up until a few weeks ago, Rhabdophis was the focus of my PhD dissertation, and though I will still be doing work on the genus, it won't be the focus of my dissertation, but instead just a side project.

Edit: "poisonous" as in having specialized glands for sequestering poison. I'd need to read again about Thamnophis, but I thought they just stored it in their tissues and didn't have specialized glands specifically for that purpose

Image

Image

Nuchal fluid from a R. nuchalis (the fluid is the iodine colored liquid on my finger)
Image

Most members can't actively secrete the poisons like subminiatus can. So far, it seems like subminiatus is the only one capable of that. All of species that I have encountered simply do the posturing, exposing the nuchal glands. Here is a Chinese R. tigrinus posturing:
Image

A slight posture on a R. nigrocinctus:
Image

Posturing in a juvenile R. nuchalis:
Image
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Chris Smith
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Re: Poisonous snakes...?

Post by Chris Smith »

Thanks!

-Chris
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Rich in Reptiles
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Re: Poisonous snakes...?

Post by Rich in Reptiles »

Wow... i had no idea that there was a species of snake that is poisonous. This led me to do a bit more research on my own.

Kevin- I read somewhere that a study was done on some keelbacks (R. tigrinus i believe) and the ones that lived on toad-free islands lacked the toxins. Do you know if they were just lacking the toxins, or the Nuchal gland altogether?
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Re: Poisonous snakes...?

Post by MonarchzMan »

There was a paper that just came out about toxin sequestration in Rhabdophis tigrinus in the Journal of Zoology. Coming from the dart frog side of things, I found this really cool!
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Re: Poisonous snakes...?

Post by Kevin Messenger »

Hey there. On the toad free island the tigrinus animals still have the nuchal glands, the nuchal fluid is just interstitial fluid, lacking any bufodienolides. But if you take those island animals, and feed them a Bufo japonicus, they will then sequester the poisons.

You can also take a mainland animal, full of toxins, deprive it of toads, put it on a toad free diet, and it will lose the poisons. This is because the animals don't create the poisons themselves, obviously.

Another really cool part is the fact that mothers pass the poisons on to the young.

An even COOLER fact; if you have a poison-free mother, she lays eggs. Those developing embryos will be poison-free upon hatching. BUT, if you put bufodienolides on the outside of the egg-shell, like paint it on for example, the egg shell will absorb the poisons, and those babies will hatch out with the poisons in their nuchal glands, whereas the other eggs that didn't get painted, will hatch out poison-free. Craziness
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Rich in Reptiles
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Re: Poisonous snakes...?

Post by Rich in Reptiles »

That is incredible!!!!! What an amazing species... thanks Kevin!
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Kevin Messenger
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Re: Poisonous snakes...?

Post by Kevin Messenger »

we are going to be doing some comparative studies this year with some specimens we have here on campus (right now we have 4 R. subminiatus, and 2 R. tigrinus). Dietary studies and behavioral.

One of the coolest observations I had was in 2011 when we caught a subminiatus that literally sprayed the poison into the air, out the back of its neck, almost like an aerosol. I'd LOVE to capture that on video. So far I've been unsuccessful. Still trying to get all the specimens on a regular feeding schedule
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Re: Poisonous snakes...?

Post by Coluber Constrictor »

Interesting stuff. I had never heard of this before. I could swear I heard somewhere that coral snakes are poisonous to eat, but I am pretty sure that is a myth.
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Re: Poisonous snakes...?

Post by Kevin Messenger »

yeah, just a myth there. They don't have anything toxic in their tissues (except within the venom glands).
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Re: Poisonous snakes...?

Post by Rich in Reptiles »

Ok, i am seriously taken by this species!! Studies on what campus? My dad works in Huntsville... :shock:
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Kevin Messenger
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Re: Poisonous snakes...?

Post by Kevin Messenger »

Oh, wow. Alabama A & M University. If you are curious, want to see them, feel free to contact me and we can make an arrangement. I will be in the country for about 1 more month. I'll be leaving for China again in early May, not returning until mid-August. We will probably be looking for some help over the summer by the way, interns and what not. I need someone to care for, feed, clean, etc - as well as run some experiments. Depending on your experience level, we may be able to work something out. Especially if you're only interested in experience (in other words, a volunteer - not a paid intern). Anyway, send me a PM
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Re: Poisonous snakes...?

Post by WW** »

Awesome thread! Loved those photos of the secretions on the neck!

The bit that is worth adding on (because it got lost in the media frenzy) is that Rhabdophis is both venomous and poisonous: it has a perfectly good venom (Duvernoy's) gland secreting toxins generated by the snake which it will inject by biting, and R. tigrinus has caused human deaths this way. That is an entirely different system from the nuchal gland that contains toad toxins, which is a poison system. It's also a nice illustration of the primarily foraging function of the venom system, as opposed to the entirely defensive function of the poison system.
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Kevin Messenger
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Re: Poisonous snakes...?

Post by Kevin Messenger »

Very good point to bring up, didn't realize we haven't already revealed that fact.
Tigrinus has caused deaths, and I have heard there is at least one recent death from subminiatus, but it almost seems to be on the level of rumor or word of mouth. I do not know of the original source that reported the death in other words. But, it should be noted that the toxicity of subminiatus is approximately twice that of tigrinus, and depending on the route of envenomation, approaches toxicity levels on par with Bungarus multicinctus (also depending on the route of course).
Take home is: "to treat the genus with extreme caution"
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Hans Breuer (twoton)
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Re: Poisonous snakes...?

Post by Hans Breuer (twoton) »

More on R. tigrinus here. (See "Biology & Ecology")
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Re: Poisonous snakes...?

Post by Reptiluvr »

Well I learned some new things today! I assume like Dendrobatid and Mantellid frogs, these Bufonids are sequestering their bufadienolides from an arthropod source. The arthropod probably gets it from a plant, I haven't read much on how plants source such poisons. Is there a bird in the region that is particularly fond of eating snakes? If so, I bet there could be room for one more step up in the food chain. It happens in New Guinea with the Pitohui species with one less intermediate, maybe there's another bird(s) out there that can sequester poisons (although those are alkaloids).
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Kevin Messenger
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Re: Poisonous snakes...?

Post by Kevin Messenger »

I unfortunately do not know enough about Bufo physiology, but I was under the impression that they do not sequester toxins from prey in the same way, but that their body actually creates the poisons. Take a cane toad out of the wild, feed it a diet of ____, it's secretions are still just as toxic as before (whereas this obviously isn't the case with Rhabdophis and Dendrobatid frogs).

I don't know for a fact, just my thought process. I'm guessing they create the alkaloids from various components of prey/ nutrition, etc, but the pathway is still not as "direct" as simple sequestration from X prey source.

Cane toad secretions are deadly in Australia, in its natural range, and in FL. And I know in FL they are known to scarf down dog and cat food left outside for pets. Seems unlikely that these 3 places have the same necessary prey source, and that basically the cane toad takes whatever sources it needs, and creates the poisons from that. Wish someone with more knowledge would comment on the topic though.
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Chris Smith
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Re: Poisonous snakes...?

Post by Chris Smith »

This has turned into a great educational thread!!

Thanks again all!

-Chris
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Re: Poisonous snakes...?

Post by kkchome »

If I remember correctly, the death happened in Singapore.
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Re: Poisonous snakes...?

Post by Kevin Messenger »

Interesting.... where the species is no longer found. Guess it was a captive

for anyone else curious about visualizing the glands, here is a tigrinus specimen that died, and since I was extremely curious about actually seeing these nuchal glands, I did a simple dissection (as well as to look for the cause of death)

Image

If anyone is curious about papers related to all of this, here are the "main" papers:

Hutchinson, Deborah A., Alan H. Savitzky, Akira Mori, Gordon M. Burghardt, Jerrold Meinwald, and Frank C. Schroeder. 2011. Chemical investigations of defensive steroid sequestration by the Asian snake Rhabdophis tigrinus. Chemoecology.

Hutchinson, Deborah A., Akira Mori, Alan Savitzky, Gordon M. Burghardt, Xiaogang Wu, Jerrold Meinwald, and Frank C. Schroeder. 2007. Dietary sequestration of defensive steroids in nuchal glands of the Asian snake Rhabdophis tigrinus. Proc Natl Aca Sci 104:2265-2270.

Hutchinson, Deborah A., Alan H. Savitzky, Akira Mori, Jerrold Meinwald, and Frank C. Schroeder. 2008. Maternal provisioning of sequestered defensive steroids by the Asian snake Rhabdophis tigrinus. Chemoecology 18:181-190.

Mori, Akira, Gordon M. Burghardt, Alan H. Savitzky, Kathleen A. Roberts, Deborah A. Hutchinson, and Richard C. Goris. 2011. Nuchal glands: a novel defensive system in snakes. Chemoecology.

Mori, Akira, and Gordon M. Burghardt. 2008. Comparative experimental tests of natricine antipredator displays, with special reference to the apparently unique displays in the Asian genus, Rhabdophis. Journal of Ethology 26:61-68.
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Re: Poisonous snakes...?

Post by Hans Breuer (twoton) »

Kevin Messenger wrote:Interesting.... where the species is no longer found. Guess it was a captive
It was, and the Singapore incident kickstarted a huge to-do in the pet trade, as the species had been thought totally harmless until that day.
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Re: Poisonous snakes...?

Post by Kevin Messenger »

huh, interesting. Yeah, I know, it's quite shocking. I wonder how venomous R. nuchalis really is. They never attempt to bite, but it would be crazy if they are just as venomous, if not more than their relatives
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Re: Poisonous snakes...?

Post by Hans Breuer (twoton) »

Kevin Messenger wrote:They never attempt to bite
Neither do kraits. Nuff said.
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Re: Poisonous snakes...?

Post by WW** »

Kevin Messenger wrote:huh, interesting. Yeah, I know, it's quite shocking. I wonder how venomous R. nuchalis really is. They never attempt to bite, but it would be crazy if they are just as venomous, if not more than their relatives
Colubrids that "never bite" are the ones that should worry you most. Among Asian natricines, we know that Xenochrophis is harmless because otherwise there would be nobody left alive in the padi fields - they are common as anything in many places and bite every time, all the time. If they had the potential to be dangerous, we would know it. On the other hand, in the case of R. nuchalis and presumably various other species of Rhabdophis, we have no idea what a bite might do because hardly anoyone has ever been bitten.

I suspect that playing with one after handling toads would be the way to find out, but don't expect me to volunteer!
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