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RE: Snake Venom
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by Charper on March 19, 2002
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Hmmmmm. Tough question really, since the two are very different in their effect. I would have to say though, that neurotoxic venoms tend to kill much faster. Also, if you were looking at it from a drop for drop perspective, neurotoxins win hands down. It takes a much larger liquid volume of hemotoxins to kill. It's really an apples and oranges kind of question though.
CH
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RE: Snake Venom
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by Naja_oxiana on March 19, 2002
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I think that Chris has pretty much summed it up. I'm personally of the school of thought that simply classifieing it as neuro- vs. heamo- is to great of a simplification.
One thing to remember is that most of the snakes who use so-called heamotoxic venoms do deep intramuscular injections and have generally slower metabolisms. The "heamo-toxic" venoms aid in the digestive cycle in that they break down a large ammount of tissues before the prey even gets into the snake's belly. This is one reason why vpers--who generally are regarded as having the heamo-toxic venoms--are so wide spread. Their venoms have evolved to be useful in a myriad of climates.
Neuro-toxic venoms are most commonly found in elapids--cobras and such, but are also predominant in a few warm climate vipers--notable C.d. terrificus and Pseudocerastes. The snakes that use neuro-toxic venoms generally have higher metabolisms and don't need the digestive properties of the heamo-toxic venms. Consequintly, you'll be hard pressed to find a predominatly neuro-toxic venom in a colder climate.
Chris is right. It's compairing apples to oranges because the venoms evolved differently to fit into totally different sets of conditions.
Cheers
Roger
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RE: Snake Venom
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by Naja_oxiana on March 19, 2002
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I made this post quite a few months ago..It's pretains to this so I'm going to post it again.
Cheers
Roger
One of the functions of venom is digestion. An interesting question is whether venom is meant to kill quickly or immobilize quickly and kill slowly. Take, for instance, the black widow spider. It uses venom to paralyze prey so that it can extract hemolymphs and other boduly fluids. For ease, the prey must still be alive for this. (In other words, it would be a lot harder were the prey dead.)
Venomous snakes are a little different in that their venom is designed to do more than just paralyze, but also kill the prey. This is why the venom can take so long to take effect. (In Elapid bites a human death is unusual in under four hours, and in viper bites, death is unusual in under 12 hours.) A snake injects the venom, which first immobilizes the prey but it stay's alive long enough for the venom to circulate throughout the bloodstream.
While I generally dislike generalizing types of venom into neuro- and heamotoxic, I will here for ease. Vipers generally have heamotoxic venoms which are enjected via longer fangs, which allow for the venom to be injected deeper into the prey and be absorbed into more of the body tussue. (ie, into muscle tissue and the blood stream.) Clearly if the venom was designed to kill immediatly, this would not work. However, a speedy immobilization is advantagous to the snake as the prey may not get very far.
Early workers in toxinology noticed how quickly envenomated mice underwent digestion when the snakes regergitated them. Interestingly, Reichert noted in Bothrops jaracussu that when live prey was fed, the given digestive cycle was 4 to 5 days, but when pre-killed prey was given the cycle was 12-14 days. Zeller even quotesa a report by Stimmler-Morath which indicates that in Vipera aspis, there is an increase of 2-5 days in digestion time of envenomated and non-envenomated prey. Also interesting was the studies of Thomas and Pough, which demonstrated that the venom of Crotalus atrox accelerated the rupture of the visceral contents of the prey. This keeps bacteria from building up in the prey's stomach. Aditionally the venom aided the loosening of hair. Little things like this aid in the snake's digestion of it's prey.
What have I deduced from this? Venoms which act mainly on the blood stream and permiable tissues are probably the more advanced venoms, as opposed to those that work primarily on neuromuscular tissues and transmissions. The more advanced venom aids ina quicker digestion cycle by breaking down the prey before the snake begins to eat it. (I know of no studies of the digestive functions of more neuromuscular venoms.) Aditionally, I now understand why solenoglyphy is considered the more advanced of the glyphous conditions.
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RE: Snake Venom
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Anonymous post on March 19, 2002
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Dose the russle's Viper have more neuro than hema toxins?
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RE: Snake Venom
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by Naja_oxiana on March 19, 2002
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There are certainly some neuro-toxic symptoms, but death from neurological symptoms stemming from a Russel'd bite are unlikely. (Though certainly not impossible.)
BGF or WW could better answer this.
Cheers
Roger
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RE: Snake Venom
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by TIMFRIEDE on March 20, 2002
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The neuro is no. 1, no q's. It can rock u fast, depending on the amt. and type of neuro. Polylepis can put u down in 15 mins and so can a lot of cobras. It comes down to where they hit u in the PNS, not the CNS, then throw in the cardios. They all can kill in different ways, but it's the combo that hits u. Neuro, cardio, hemo, blah blah. Tim
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