Scorpion's two types of Venom

Bob the thief

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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.
 

skinheaddave

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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
 

Kenny

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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.
 

XOskeletonRED

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

edw.
 

errit

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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.
 

G. Carnell

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

fusion121

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"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
 

fusion121

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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.
 

protheus

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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
 

fusion121

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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.
 

deifiler

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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...
 

protheus

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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
 

fusion121

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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 andor make an impression by causing intense
pain. Alternatively, immobilizing a small arthropod just enough
to subdue and initiate feeding on it is also advantageous. For
example, prevenom may distract a mammal because of its pain
causing and ‘‘hyperactivating’’ abilities, giving the scorpion an
opportunity to escape. On the other hand, in cases where its life
is in danger, the scorpion may need to defend itself with the
utmost urgency, thus justifying the presence of a more deadly
mixture, the venom.
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?
 

Eurypterid

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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.
 

fusion121

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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.

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...
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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