# Scorpion's two types of Venom



## Kugellager (Jan 21, 2003)

Here is an article that discusses two type of scorpion venom. Interesting article.


http://news.yahoo.com/news?tmpl=story2&cid=624&ncid=753&e=10&u=/ap/20030120/ap_on_sc/scorpion_venoms

John
];')


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## Bob the thief (Jan 21, 2003)

That would explain sooo many things we have wondered about scorpions. And why my Spadix when held makes a whiteish liquid and when I just push the top off the coconut she uses as a burrow its just a clear watery liquid.


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## skinheaddave (Jan 21, 2003)

Wow!  That's pretty facinating stuff.  It goes further towards explaining the wide range of symptom severity exhibited by people stung by the same scorpion.

Cheers,
Dave


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## Mojo Jojo (Jan 21, 2003)

Interesting!  

Jon


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## atavuss (Jan 21, 2003)

fascinating!  thanks for posting the link!
Ed


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## Kenny (Jan 22, 2003)

*Hi*

Yesterday I saw this a matter of fact on CNN at the bottom of the TV screen where they have this scrolling news line going sideways.

It said that new studies shows that scorpions uses 2 venoms.



It was also on CNN  some week ago that they try to research scorpion venom for cancer treatment.


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## XOskeletonRED (Jan 24, 2003)

hmmmm... *scratches head* most intriguing. I'm gonna go read more about this new found discovery. 

edw.


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## errit (Jul 15, 2004)

It makes no sens, in order for the scorpion to have 2 different venoms it needs to have 2 venom sacs or two differnt kind of venom glands in one venom sac.


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## G. Carnell (Jul 15, 2004)

there are 2 venom glands... in the telson (i believe)
i doubt they produce different venoms though


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## fusion121 (Jul 15, 2004)

> "Inceoglu & al., 2003. One Scorpion, two venoms: Prevenom of Parabuthus transvaalicus acts as an alternative type of venom with distinct mechanism of action. In PNAS, vol.100, no.3"


I can't seem to reach the article now but there was a discussion on the different venoms of scorpions recently and eric referenced the above paper. You can get it here, very intresting stuff:
Scorpion venoms


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## Eurypterid (Jul 15, 2004)

There was an involved debate about this in an earlier thread:

Two Venoms?


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## carpe scorpio (Jul 15, 2004)

Very interesting material, thanks for bringing this to us.


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## fusion121 (Jul 15, 2004)

Eurypterid said:
			
		

> There was an involved debate about this in an earlier thread:
> 
> Two Venoms?


Interesting debate, you raise good points about the paper and you may well be right, they say: 



> Chemical analysis of prevenom shows that it contains about
> sixfold less protein and sixteenfold higher concentration of K
> salt than venom. Metabolically speaking, K+ salt is likely to be
> less expensive to the scorpion compared with peptide toxins.


Your point about separation of components fits with this as K+ (albeit charged) will pass through a membrane faster then most proteins the HPLC also bears out the fact that higher weight protiens exisit mainly in the venom, which would account for the change is composition of prevenom. ( I'd guess mechanistically the strcutures in a scorpions telson act much like a chromatographic column so its little wonder they got this result.) 

Its difficult to say whether scorpions have an mechanical control over venom used, I don't think different venom sacks have ever been identified, so its hard to believe they could moderate venom composition using chemical processes in the short time required before a sting is administered. 

Futhermore the papers:


> We propose that the prevenom of scorpions is used as a
> highly efficacious predator deterrent and for immobilizing small
> prey while conserving metabolically expensive venom until a
> certain level of stimuli is reached, after which the venom is
> secreted.


Scorpions are simple creatures and we know that their view of the world is based on virational/chemical and some visual components, using these I'm skeptical a scorpion could really effectively draw then line between "levels of stimuli" (though of course who knows what a scorpion really experiences". As to the level of stimuli I'm not even sure what they are referring to, if prevenom can deal with predators and small prey why would venom ever be used if its metabolically expensive? As you say the paper in a chemical one, not a behaviourial one.


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## protheus (Jul 16, 2004)

fusion121 said:
			
		

> As to the level of stimuli I'm not even sure what they are referring to, if prevenom can deal with predators and small prey why would venom ever be used if its metabolically expensive? As you say the paper in a chemical one, not a behaviourial one.


My guess would be that the "real" venom may be used more often in predators (large ones that won't give up  ) than prey.  Just a thought.

Chris


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## fusion121 (Jul 16, 2004)

protheus said:
			
		

> My guess would be that the "real" venom may be used more often in predators (large ones that won't give up  ) than prey.  Just a thought.
> 
> Chris


Thats what I would have thought, but the article claims that the prevenom is more effective in a defensive situation, a behavioural study would be best.


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## deifiler (Jul 16, 2004)

fusion121 said:
			
		

> ....using these I'm skeptical a scorpion could really effectively draw then line between "levels of stimuli" (though of course who knows what a scorpion really experiences". As to the level of stimuli I'm not even sure what they are referring to, if prevenom can deal with predators and small prey why would venom ever be used if its metabolically expensive? As you say the paper in a chemical one, not a behaviourial one.


I'd assume the stimuli is regarding the way the scorpion interpretates other organisms: prey items, such as flies and other invertebrates are going to produce vibrations that vastly differ in wavelength and amplitude to those of a larger specimen such as a natural mammalian predator of the scorpion. An example proposed in the ever lovely "black-and-white" style would be to compare the beating of fly's wings to the stomps of a dog.

I guess proof of the ability to distinguish between the differing wavelengths would be the ability of detecting and catching prey during windy periods etc.

 Obviously this won't be the only way that 'stimuli' levels are determined. Possibly to the extent of chemoreceptors detecting chemicals that can distinguish between the two.

Also other factors, such as time of day or the 'frameset' the scorpion is in (assuming scorpions have such things e.g., primarily in an active hunting behaviour at night periods.)

Ahh the article isn't loading for me :< I'd love to read it though and maybe comment some more...


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## protheus (Jul 16, 2004)

fusion121 said:
			
		

> Thats what I would have thought, but the article claims that the prevenom is more effective in a defensive situation, a behavioural study would be best.


My reading of the paper suggests the prevenom to be quick and painful, while the actual venom is somewhat slower and more lethal; I could be wrong, of course.  (A mixture of the two might be both?)

Chris


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## fusion121 (Jul 16, 2004)

> The desired effect of venom from the perspective of the
> scorpion is likely to be severalfold. Under natural conditions for
> routine encounters, it may be advantageous for a scorpion to
> deter a predator andor make an impression by causing intense
> ...


No your quite right I must have missed that bit sorry, though the slower acting nature would suggest it may not help the scorpion in a defensive situation, of course its pure supposition on the part of the authors so who knows?


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## Eurypterid (Jul 16, 2004)

fusion121 said:
			
		

> No your quite right I must have missed that bit sorry, though the slower acting nature would suggest it may not help the scorpion in a defensive situation, of course its pure supposition on the part of the authors so who knows?



This was part of my point in the earlier thread as well. When you really think about it, the supposed "strategies" that the authors propose don't really make sense. It requires that the scorpion either be able to evaluate a threat intelligently before stinging (which I doubt), or to spend the greatest amount of time subduing the greatest threats (sting with "prevenom" first, determine that "prevenom" is insufficient, then sting again with slow-acting venom). This is a strategy guaranteed to get you killed. The greatest threats are those that require the fastest response. Assuming scorpions can't evaluate threats beforehand, the best strategy would be to hit any threat with the strongest venom first, in which case "prevenom" would be worthless. If they can evaluate threats, then we should see scorpions putting out their strongest venom first sometimes. But according to the authors, prevenom is *always* first, which seems to indicate it is nothing more than simple leakage of a little of the least viscous components of the venom first, not a unique form of venom or part of a complex venom-use strategy.

Also, as I noted in the earlier thread, there have been no studies to even show that venom production imposes a significant metabolic cost on scorpions, so there's no reason to believe that such a cost-saving strategy would have any purpose to begin with. I think they found a very interesting result in the fact that the K+ ions in the thinner fluid component of venom is a significant contributor to the effects of the venom. That is a fantastic find that really shows the elegance of venom composition and function. But instead focusing on that, they tried to concoct a huge "just so" story about complex evolutionary strategies for which there is no evidence nor justification. It turns a solid piece of research into a paper I'd expect from an undergrad with too little guidance.


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## fusion121 (Jul 17, 2004)

deifiler said:
			
		

> I'd assume the stimuli is regarding the way the scorpion interpretates other organisms: prey items, such as flies and other invertebrates are going to produce vibrations that vastly differ in wavelength and amplitude to those of a larger specimen such as a natural mammalian predator of the scorpion. An example proposed in the ever lovely "black-and-white" style would be to compare the beating of fly's wings to the stomps of a dog.
> 
> I guess proof of the ability to distinguish between the differing wavelengths would be the ability of detecting and catching prey during windy periods etc.
> 
> ...


As you say scorpions will be able to determine at the extreme of the encounter range, but I'm not sure they can accurately determine whether something is predator or prey inbetween(and I've often seen this with larger crickets, the scorpion seems "confused" on how to act for a while), say with a solfugid, how is the scorpion supposed to determine wether it is prey or predator and then alter its venom according all in a short space of time. The chemical stimuli will be relatively unimportant in this instance, firstly thinking about it in terms of rates of diffusion in the quick prey/predator interaction, and also we don't know whether scorpions can even detect volatile chemical components, as yet only direct contact has been proved. As such by the time a direct contact is made the predator/prey debate is already over. Sight again, while they could determine between large and small in the middle they would again have difficulty.
They have to work with a very limited amount of information in a small amount of time and with other organisms of a similar size I think they would have a great deal of difficultly in making up their "mind" as to the correct response, hence I don't think they could pre-emptively prepare the appropriate venom mix.


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## fusion121 (Jul 17, 2004)

Eurypterid said:
			
		

> Also, as I noted in the earlier thread, there have been no studies to even show that venom production imposes a significant metabolic cost on scorpions


I'm surprised this hasn't been investigated considering the number of studies of scorpion venom, it would be interesting to find out as the author does seem to have taken it a priori. The leakage of the venoms more mobile components would seem to the better explanation for prevenom especially considering the HPLC results.


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## Eurypterid (Jul 17, 2004)

fusion121 said:
			
		

> I'm surprised this hasn't been investigated considering the number of studies of scorpion venom, it would be interesting to find out as the author does seem to have taken it a priori. The leakage of the venoms more mobile components would seem to the better explanation for prevenom especially considering the HPLC results.


In the literature this is a common assumption due to the protein content. But as far as I know it has never been tested, and the authors cite no source in this paper, so they apparently don't know of such an experiment either. So, while venom may be a costly substance to make in an absolute sense, it may not be a significant cost when put in terms of actual usage.

I've been thinking of having a student do such an experiment, but there are some diffculties. We could extract venom and measure the metabolic costs of replacement, but we run into some difficulties putting that into the context of real-world venom usage. It would be difficult to quantify the average amount of venom used by a scorpion over a given period of time. It would be hard enough to get a good sampling of the average number of stings the scopion may have to deliver over say a week, and that is further complicated by not being able to measure the amount of venom used in each sting. Without that data there is no way to determine whether there is actually a significant metabolic cost associated with venom usage in nature. Hmmm. Just writing this I thought of an experiment that could probably give us the information we need, though it wouldn't be easy. Maybe I'll have a couple of students work on it this fall.


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## fusion121 (Jul 17, 2004)

Eurypterid said:
			
		

> In the literature this is a common assumption due to the protein content. But as far as I know it has never been tested, and the authors cite no source in this paper, so they apparently don't know of such an experiment either. So, while venom may be a costly substance to make in an absolute sense, it may not be a significant cost when put in terms of actual usage.
> 
> I've been thinking of having a student do such an experiment, but there are some diffculties. We could extract venom and measure the metabolic costs of replacement, but we run into some difficulties putting that into the context of real-world venom usage. It would be difficult to quantify the average amount of venom used by a scorpion over a given period of time. It would be hard enough to get a good sampling of the average number of stings the scopion may have to deliver over say a week, and that is further complicated by not being able to measure the amount of venom used in each sting. Without that data there is no way to determine whether there is actually a significant metabolic cost associated with venom usage in nature. Hmmm. Just writing this I thought of an experiment that could probably give us the information we need, though it wouldn't be easy. Maybe I'll have a couple of students work on it this fall.


It would be important research I've read papers on venom metering by venemous snakes and in those to they were unable to refer to any empircal data on the metabolic cost of venom production. I've no knowledge of how one sets up experiments like this. I assume its not as simple as taking scorpions of known mass, not feeding them, and then milking each one for different amounts of venom and then correlating decrease in mass (and hence I assume expended energy, obviously ignoring the mass of the milked venom itself) with mass of venom used? Though that would have been my first guess.


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## Eurypterid (Jul 17, 2004)

Simply using masses wouldn't be very accurate, since the mass of expended venom would be so small compared to the total mass of the animal. Changes would be complicated by defication, dehydration, etc. Just too messy. But the caloric content of venom could be measured, average and total metabolism of scorps could be measured, venom production rates could be calculated, etc. These experiments could give us a good idea of the base venom-producing capacity of scorpions, and then we would just need to measure average usage in nature. I say "just", but this would actually be the harder part. I guess I just found a use for my 500+ _C. gracilis_.


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## fusion121 (Jul 17, 2004)

Eurypterid said:
			
		

> Simply using masses wouldn't be very accurate, since the mass of expended venom would be so small compared to the total mass of the animal. Changes would be complicated by defication, dehydration, etc. Just too messy. But the caloric content of venom could be measured, average and total metabolism of scorps could be measured, venom production rates could be calculated, etc. These experiments could give us a good idea of the base venom-producing capacity of scorpions, and then we would just need to measure average usage in nature. I say "just", but this would actually be the harder part. I guess I just found a use for my 500+ _C. gracilis_.


I'll be very interested to read the results if you publish a paper on it, as I suspect will many researchers with venemous animals would be.


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## Eurypterid (Jul 17, 2004)

fusion121 said:
			
		

> I'll be very interested to read the results if you publish a paper on it, as I suspect will many researchers with venemous animals would be.


Well, with student research it may take a year or so, but if we get interesting results I'll certainly post something here.


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