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Fang placement and venom delivery
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by Parcelmouth on May 5, 2003
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Could some one please explain the diffrence in fang placement,structure,lenth and venom delivery systems of venomous snakes.Why are rear fanged colubrids(i.e. false water cobras) not considered dangerous to humans also why are boomslangs extreamly dangerous even though they have rear fangs and Duvernoy's glands is it fang lenth, venom delivery(i.e. do they inject venom or have to "chew" it in like most rear fanged snakes)?Also what is the diffrence between elapid venom delivery and viper and pit viper delivery system as pertaining to fang structure and lenth,mechanisms of strike,venom injection,structure of venom glands, skull and musculature controling this process?Also,could someone explain a little about fangs and venom delivery of burrowing asps(Atractaspididae)?Please excuse my spelling and thank you for your replys.
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RE: Fang placement and venom delivery
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by Rabies on May 5, 2003
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I don't want to be rude or start a flame war.The questions you ask are very feasible for somebody with no knowledge or basic knowledge of snakes.But for somebody who already has/keeps venomous I find this worrying.Its like buying a gun,chambering a bullet and then asking sombody"how does it work"
Please don't take affence,maybe somebody will take the time to answer you questions.
John
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RE: Fang placement and venom delivery
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by BGF on May 5, 2003
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Some interesting questions you have there and the answer is that the situation is actually easier to understand than expected (the evolution of venom) or are actually more diverse than normally appreciated (just how many snake families there are).
Venom evolution is actually quite logical. Think of it this way, which came first? The ability to make noise or an intricate piece of architecture like a voice box? Its doesn't make much sense to go through the precision needed for speach if there wasn't a noice to distort? The same thing is there in the continuity between the elapids and the taxonomical dumping ground called the 'colubrids'. The colubrids as a natural group simply don't exist. Some of the families, such as the Psammophiinae (e.g. Psammophis) and Pseudoxyrhophiinae (e.g. Leioheterodon) are actually more elapid like than 'colubrid', indeed they actually sit at the base of the elapid tree. Makes a bit of sense to anyone who's ever worked with Psammophis. They definately acted like 'protoelapids' which is what we affectionally called them. Very cool. Very common. Very hot. And I mean knock you on your bloody bottom hot. For example, we had one 1.2 meter Psammophis mossambica kill seven fuzzy rats. In a row. Chewed each only three quick times and then just waited. As if it knew something was going to happen. They are definately using the toxins for prey capture .
So if the gland predates the intricate system of aducter muscles and ducts, which it of course does since you wouldn't build advanched delivery mechanisms like fangs if there wasn't anything already there to deliver. Thats exactly what the situation is. We have several papers on the subject coming out that quite clearly demonstrate the inherently venomous nature of snakes and the suprising diversity of venoms and the relationship of Elapidae with some very unexpected company.
Basically, from a biochemical perspective, we've shown that the colubrids are by and large just basically elapids that haven't got the really advanced teeth. Still tweaking the toxins, lots of variations in fangs lengths and locations and some of the most unlikely snakes have the toxins. We'll have the first three papers on this out within the next two months. Two have already been accepted and the third goes in for review within the next fortnight.
In case your interested, some of the major lineages we've worked on are. Atractaspidae (Atractaspis), Colubrinae (Ahaetulla, Boiga, Coelognathus, Coluber, Dispholidus, Gonyosoma, Ptyas, Telescopus, Trimorphodon), Elapidae (Aipysurus, Aspidelaps, Cryptophis, Demansia, Dendroaspis, Echiopsis, Enhydrina, Glyphodon, Lapemis, Laticauda, Micropechis, Pelamis, Suta), Homalopsinae (Cerberus), Natricinae (Rhabdophis), Psammophiinae (Psammophis), Pseudoxyrhophiinae (Leioheterodon), Xendontinae (Heterodon, Philodryas) and Viperidae (Azemiops, Causus, Proatheris, Tropidolaeumus). Some of them proved 'interesting' to milk. ;-)
Each one is unique in its own way, all are technically venomous. This is operating upon the assumption that venomous is defined as possessing a conserved gland that may be bigger or smaller than anticipated. But the toxins are largely the same sorts. If thats the definition, then they are all venomous. Of course doesn't mean that all have fangs or all will cause dangerous bites but some that you wouldn't have picked actually are quite copious venom yielders.
So criticism of not knowing can't really be fairly leveled. We certainly didn't predict where we would find such things, in fact even our intended bloody negative control of the first study turned out to have the same bloody toxins! Thats about when things started getting really scary. Things like 30 - 40 cm Telescopus dhara giving upwards 15-18 mgs (dry weight) of what turns out to be quite potent venom. By the way, these snakes get to 1.2 meters! Sorta makes you wonder doesn't it? And there's no way we would have predicted that. Not when Telescopus get sold through pet stores and are normally are thought of as basically non-venomous. Wanna know why they don't really hammer somone? Give someone a real smacking? Its because while they have absolutely mamooth venom glands, bigger than a lot of elapids, they also have really crappy fangs in addition to a pretty placid temperment. Disinclination to bite means any snaps probably will be half hearted and tiny fangs pretty much gaurantees the fangs won't go in without a really serious chomp. So, very low likelihood of envenomation. But if it somehow got it all into you, you'd be in a world of hurt.
Similarly is Psammophis mossambiceus, this is the one that is mistakenly sold as Psammophis sibilans (the true P. sibilans is a tiny little snake). It also has huge venom glands, gets to 1.2 m or longer, aggressive, well developed teeth, good at getting the venom in. We expected them to be a bit nasty but we certainly didn't anticipate elapid level toxicity or some interesting evolution of venom and a lot of it. Also, due to the snakes being so different, its not highly likely that the elapid antivenoms will do much good. Elapid antivenoms normally have a limited enough range of which elapids they'll work against, let alone some weird sand snake from a dusty part of Africa!!!
So as you can see, its easier than we thought in that venom is ancient. Pretty logical in many ways. Some of the truly non-venomous (e.g. Pituophis, Lampropeltis) have undergone a secondary loss of the gland. In other words, they had the gland but when they split off, the gland was still pretty small so it was no great feat for them to flex their muscles a bit more and chew a bit less. However, things are also more complex, with snakes being lot more very diverse than is usually known. This diversity includes a couple very ancient splits.
Its a fascinating area.
Cheers
BGF
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RE: Fang placement and venom delivery
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Anonymous post on May 5, 2003
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You know rabies its really sad that you were the first post since I would be willing to bet my paycheck that you CAN NOT answer all of those questions. I have been in this lifestyle(reptiles) for a long time and I could answer a few of those Q's but not all of them. I really hope someone takes the time to answer these Q's, because I am currious also.
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RE: Fang placement and venom delivery
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by TAIPAN78 on May 6, 2003
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Brian,
That was one hell of a reply!! I cant wait to see your work. I had no idea you were looking into Aspidelaps though. Which sp and how did their venom turn out as far as toxcicity is concerned? Is this info you can give now or do I have to wait? Damn it, I hate waiting!!!! LOL
Anyway, thanks for the awsome info!
All the best PWD,
J
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RE: Fang placement and venom delivery
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by BGF on May 6, 2003
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Hey mate
Fangs for that. It was Aspidelaps lubricus and it was generic elapid. Nothing really different. This means that a bite from it would be about the same as a bite from a comparable African elapid. Would you be blase about one that size Naja mossambica? If not, then treat the Aspidelaps with the same respect.
I'll make sure to make the paper available. Wolfgang Wuster was my main collborator and he's got some great things going on his side with the taxonomy. Another nice series over there. Between the two of us we've happily hatched lots of trouble. Keeps us amused. Drives the heads of department batty though. A pleasent side effect.
Cheers
B
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RE: Fang placement and venom delivery
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by Rabies on May 6, 2003
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To Anon,I couldnt of answered all of those questions and especially in the detail that BGF has gone and done.But you see time and time again people asking question that refer to basic anatomy and physiology ie fang placement,structure,delivery system etc.The only reason I reply'd so,was that according to his profile he is already keeping venomous snakes and as far as i was concerned he should have knowledge within this area prior to purchasing.I will take the time to answer questions where possible but I do get up tight when people are asking some of the basic quetions AFTER purchasing venomous reptiles.
regards
John
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RE: Fang placement and venom delivery
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by TAIPAN78 on May 6, 2003
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Yo B man,
I think I may have taken the statement out of contexts but when you say, "Would you be blase about one that size Naja mossambica?" im takeing it you mean a adult A.l.lubricus would be about par with a juvi N. mossambica envenomation? If that is the case, would this mean Aspidelaps lubricus venom is primarly localized in its effects, much like N.mossambica(ive always heard that their bites usualy remained localized with wide spread necrosis of the bitten limb possible but unusualy, if ever do they manifest into systematic problems)? Through my studies of the genus Aspidelaps, it would seem that envenomations from this group always end up trivial. Meaning, some victims will have only localized swelling and tendersness in the bitten limb but others will manifest into systematic or for lack of a better term, neurological smyptoms. What have you found to be the primary action in thier venom or is it too mixed up with other various actions to group under the typical neuro/hemo catogories? If this is info thats going to be released in one of your papers then I apologize and will wait for the published findings.
Also, did you ever do any work with the ssp of lubricus? It seems A.l.infuscatus is the main ssp responsible for serious envenomations in the sp(infuscatus has 2 known fatalities attributed to them) but do too their overall larger size, I belive the quanity of venom injected is the major differing factor rather then the potentancy.
As for you and WW colaborateing together, I take it he is looking into venom compisition inorder to get a better idea on the grouping of some sp/genus? Is he sticking to Naja or expanding into other genus as well? I know you cant get go into very much detail so Ill stop with my annoying questions here:-)
Well man, definately interesting stuff!! I wait egarly to read your findings!
Take care man and say whats up to Tim for me if you still see him on a regular basis.
All the best bro,
J
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RE: Fang placement and venom delivery
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by spanky on May 6, 2003
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I would like to say that I think Parcelmouth had a valid question. We that keep venomous snakes, don't have to know how all venoms are delivered. Just that thay are delivered. Good day Spanky
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RE: Fang placement and venom delivery
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by Rabies on May 6, 2003
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Hi Spanky
if you even used half of the thought process that I used for my"hot headed out burst"simple theory of venom delivery and capabilities of these agile animals may have prevented you from receiving such a large amount of envenomations over such a short period of time.
regards
John
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