# Dry bites is it a conscious choice or just a lottery?.



## Endeavour (Feb 22, 2014)

Been reading a little about venomous snakes delivering dry bites. It would appear some do this more than others. My question is. Is this something a snakes makes a 'choice' to do or is it just the luck of the draw as to whether your day is going to turn bad?.

Kindest regards

Endeavour


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## Bushman (Feb 22, 2014)

Good question mate and one that I've wondered about myself.
My thoughts are that because venom is a biologically expensive product to make, that they don't waste it unnecessarily and they will often send out warning shots first.


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## Leasdraco (Feb 22, 2014)

I find this an interesting topic. I think the snakes' ability to control venom output varies between species. It makes sense that they dont want to waste their venom on something that isn't prey. Ive heard from snake 'milkers' that some species or individuals take a fair amount of persuasion to give up their venom. Some, like Red-bellies, often chew for a few moments before releasing venom, so a quick nip is often a 'dry bite', but not predictable enough to take for granted!


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## The_Geeza (Feb 22, 2014)

There was a documentary on this exact subject using a jelly false hand... It proved that different snakes acted different... Even some of the more aggressive snakes were more inclined to dry bite but others were full out delivering a good bite... Dam can't remember what it was called


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## saximus (Feb 22, 2014)

From a biological point of view don't they need to contract specific muscles to release it from the glands meaning that it has to be conscious?


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## gus11 (Feb 22, 2014)

There are multiple papers on the rates of venom injection by various snakes, off the top of my head i seem to remember that for most aussie elapids injection rates are very low, this makes sense as stated above venom is expensive to produce, so why waste it. In general venom is used for killing prey, not as an anti-predator defense, an exception to this would be spitting cobras. Snakes have numerous antipredator defenses neck flattening, puffing the body etc., if that fails and they can't flee, dry bites should theoretically occur followed by wet bites. I think looking at the number of bites that occur from snakes around the world and the number of actual envenomation that the majority of bites are dry. Indicating snakes select to inject the venom.


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## andynic07 (Feb 22, 2014)

Not all red belly nips are dry bites. Also I thought that the mulga snake had a large venom yield.


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## Varanoidea (Feb 22, 2014)

saximus said:


> From a biological point of view don't they need to contract specific muscles to release it from the glands meaning that it has to be conscious?



I was under the impression that the force of the snakes jaws around whatever it was biting squeezed the venom glands. I can't exactly remember where I heard this. From that point of view whether or not the snake injects venom would depend on how committed it was to the bite i.e if it's just a warning it isn't going to bite hard thus no venom.


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## GBWhite (Feb 22, 2014)

Hi Endeavour,

I don't know if snakes can deliberately/intentionally choose to inject venom.

However; I remember discussing this subject with a few friends a couple of years back and I remember someone saying that they read a paper on the ejection of venom by vipers and elapid snakes, (rattlesnakes, lance heads and cobras) where it stated the injection of venom has got a lot to do with the lower jaw gaining enough purchase on a victim to provide a pivot point for the muscles at the back of the upper jaw to be able to clamp down hard enough on the venom gland to force the venom out of the glad, through the fangs and into the victim. 

So if this is correct as I assume it is, it would be a reasonable assumption that dry bites occur when the lower jaw of the snake has failed to gain a strong enough grip to cause the back muscles of the upper jaw to apply sufficient pressure on the gland and hence, force venom through the delivery system and into the victim/prey.

So in saying that it can be further assumed that dry bites may happen when a snake "snaps" in a defensive or instinctive action rather than delivering a bite where the intention is a deliberate act to inject venom and immobilize the prey or assumed threat.

George.


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## mikey_mike (Feb 22, 2014)

saximus said:


> From a biological point of view don't they need to contract specific muscles to release it from the glands meaning that it has to be conscious?



No, this doesn't require conscious control. The nature of consciousness is an interesting topic in itself, however this question can be answered simply by thinking about a few muscles in your own body.

Heart muscle - learning to control the contractions of this beasty would be a neat trick.
Lower oesophageal sphincter - apparently some sword swallowers have control over this, but the rest of us, sadly no
Uterus - any women approaching childbirth would love to have control 
Any muscle involved in a reflex arc - eg patella tap
Any muscle when you're asleep
So many more examples.

It seems self evident that some snakes are more likely to give dry bites than others. It must be influenced by so many factors - the nature & quantity of their venom, it's toxicity towards prey & potential predators, whether or not they had their morning coffee...


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## dragonlover1 (Feb 22, 2014)

mikey_mike said:


> No, this doesn't require conscious control. The nature of consciousness is an interesting topic in itself, however this question can be answered simply by thinking about a few muscles in your own body.
> 
> Heart muscle - learning to control the contractions of this beasty would be a neat trick.
> Lower oesophageal sphincter - apparently some sword swallowers have control over this, but the rest of us, sadly no
> ...


haha so funny.....morning coffee...now if I could control my heart that would be a neat trick I could stop my palpitations as I suffer from AF (atrial fibrilations)
but back to post I don't see how it could be a conscious decision as I don't think snakes are intelligent enough to think it through


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## andynic07 (Feb 22, 2014)

mikey_mike said:


> No, this doesn't require conscious control. The nature of consciousness is an interesting topic in itself, however this question can be answered simply by thinking about a few muscles in your own body.
> 
> Heart muscle - learning to control the contractions of this beasty would be a neat trick.
> Lower oesophageal sphincter - apparently some sword swallowers have control over this, but the rest of us, sadly no
> ...


Very good post but I am not seeing the link between whether the release of venom is involuntary or not to the nature and quantity of venom. I don't know how true this is but I have heard that mulga snakes have very large muscles that force venom out of the sack and also get similar to a lock jaw and this is why they have such a large venom yield.


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## GeckoJosh (Feb 22, 2014)

According to the person I recently did a ven course with feeding bites (being bitten while feeding the snake) seem too nearly every time cause en-venomation, so going by that I would say they have at least some control over their venom delivery.


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## mikey_mike (Feb 22, 2014)

GeckoJosh said:


> According to the person I recently did a ven course with feeding bites (being bitten while feeding the snake) seem too nearly every time cause en-venomation, so going by that I would say they have at least some control over their venom delivery.



Makes sense if the primary purpose of venom is to immobilise prey.


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## GBWhite (Feb 22, 2014)

It actually has two primary purposes. It's used to not only immobilise but to assist in the digestion of prey. It's basically a modification of saliva that's found in other vertebrae.

Humans and other mammals have the ability to chew their food where (as we all know) snake don't chew but swallow their prey whole.

Remember when, as a kid we are told to chew our food. Well it's not only to break it into small pieces that can be easily swallowed as a lot of people think. The chewing action creates saliva that when mixed with the food item helps to assist digestion in the gut. The more we chew our food the more saliva mixes with it and the better it digests.

Snake venom contains (as well as many other things) strong enzymes that are very important to assist in the breakdown and digestion of their prey.

Recent research has discovered that pythons have an ancient venom delivery system (not venom glands as such but a system similar to monitors where the venom is stored in small grooves in the jaws and excretes in a form of a saliva) that although not lethal, contains similar enzymes to assist in the digestion of prey (that's why python bites sting and can sometimes become infected). It's presumed that "non venomous" colubrids also have a similar system for the same purpose but it will need further research to confirm.

George.


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## andynic07 (Feb 22, 2014)

GBWhite said:


> It actually has two primary purposes. It's used to not only immobilise but to assist in the digestion of prey. It's basically a modification of saliva that's found in other vertebrae.
> 
> Humans and other mammals have the ability to chew their food where (as we all know) snake don't chew but swallow their prey whole.
> 
> ...


What are the points that distinguish venom from saliva.


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## Barrett (Feb 22, 2014)

GBWhite said:


> Hi Endeavour,
> 
> I don't know if snakes can deliberately/intentionally choose to inject venom.
> 
> ...



My only contradiction to this is from experience with my denisonia devisi. I was tagged with just one fang, with her mouth still partially open, and envenomation occured. Luckily, her venom isn't strong enough to cause anything more then slight swelling at the site. So some species may infact need to apply substantial pressure to cause a "wet bite."

Saying that, as stated before the mechanism of envenomation could vary rather substantially from species to species.

- - - Updated - - -

I checked online to find some sources that could help with this topic. I came across one article that states that certain species (such as a rattlesnake) can change their envenomation "strategies" depending on the prey items. It also states that spitting cobras - shown with diagrams - are able to change the way the project their venom. 

I'm not sure if that mean they are consciously able to change the way they envenomate prey, or not envenomate prey altogether; nonetheless it's still an interesting read that makes you wonder.

Physiology of Snake Venom - Venom Delivery


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## GBWhite (Feb 22, 2014)

andynic07 said:


> What are the points that distinguish venom from saliva.



The compounds that make up venom are primarily proteins and polypeptides and various other substances with toxic properties. Saliva is 99.5% water with the other .05% consisting of mucus, enzymes electrolytes, glycoproteins and antibacteria.

Barrett,

I can only assume that considering the devis is only a reasonable small snake with a small venom gland and also considering the mouth was partially closed. It it must have been closed enough to provide sufficient purchase off the bottom jaw to apply enough pressure from the top jaw on the venom gland to force venom out and along the delivery system. 

George.


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## andynic07 (Feb 22, 2014)

GBWhite said:


> The compounds that make up venom are primarily proteins and polypeptides and various other substances with toxic properties. Saliva is 99.5% water with the other .05% consisting of mucus, enzymes electrolytes, glycoproteins and antibacteria.
> 
> Barrett,
> 
> ...


I have just googled human saliva and enzymes are proteins and saliva also has polypeptides. Maybe it is just the strength that varies and is the difference?


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## longqi (Feb 23, 2014)

Saw scale vipers use venom against humans almost 100% of the time
King cobras rarely use venom against humans -+10%
Most pit vipers can inject venom from a fang going beside the lower jaw with mouth still nearly closed
Gabboons have been known to bite straight through their own bottom jaw to inject venom

So although using the bottom jaw may help with delivery of larger quantities of venom IMO they can pick and choose


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## cement (Feb 23, 2014)

When a drop the size of a couple of sand grains is all that is required, who's to say that residual venom on the fang or in the fang sheath was injected purposefully or just transmitted through touch.
I have heard of envenomation in keepers while cleaning cages where a shed fang has *****ed the finger, but I am unable to verify.


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## Darlyn (Feb 23, 2014)

cement said:


> When a drop the size of a couple of sand grains is all that is required, who's to say that residual venom on the fang or in the fang sheath was injected purposefully or just transmitted through touch.
> I have heard of envenomation in keepers while cleaning cages where a shed fang has *****ed the finger, but I am unable to verify.



Wow, that's pretty interesting.


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## Bluetongue1 (Feb 23, 2014)

There are three types of muscles in vertebrate animals – 


Skeletal muscle or "striated voluntary muscle" 
Smooth muscle or "non-striated involuntary muscle" 
Cardiac muscle or “striated involuntary muscle" 
 
Only *skeletal muscle* is *under conscious control*. Due to the complexities of our nervous system, it is on rare occasions possible for someone with an immense amount of specific training to exercise a measure of conscious over what is normally involuntary muscle. This is the exception to the rule, extremely rare and cannot be achieved by the vast majority who train to do so.

Unfortunately the term “conscious” has a number of meanings which can lead to confusion...


aware of one's own existence, sensations, thoughts, surroundings, etc. 
fully aware of or sensitive to something (often followed by of ): conscious of one's own faults; He wasn't conscious of the gossip about his past. 
having the mental faculties fully active: He was conscious during the operation. 
known to oneself; felt: conscious guilt. 
aware of what one is doing: a conscious liar.
Meaning 5 is the correct meaning when discussing physiology and muscles in particular.

The venom glands are not squeezed by the closing of the jaws to cause them to expel venom. Refer to pg 15 “Australian Snakes. A Natural History.” by Richard Shine. Reed Books. The “masseter muscles” attached to the back of the venom glands “contract and squeeze venom from the venom gland through the venom duct to the fang.” To put it simply, envenomation is under the control of the snake.

Studies have found that individuals within the one species can vary in their likelihood to envenomate and so the results are often given as a range e.g. 40% - 50%. It was previously believe that Australian elapids were only likely to envenomate about 10% of the time. More recent research has found this average to be closer to 50% overall. 

The amount of venom injected can vary dramatically. From the point of view of the snake, it depends on how long since it used its venom, its state of health, the degree to which the fangs penetrate and where they penetrate, the size of the snake and to what degree the snake is feeling threatened. Obviously clothing has an effect but that is independent of the snake. Those species which chew or deliver multiple bites in quick succession are likely to be more successful in envenomation. The volume of venom that a snake can build up in its venom glands is another factor influencing the success of a snake attempting to envenomate.

I have not covered it all but hopefully that sets the record straight on the misconceptions.

Blue


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## mikey_mike (Feb 23, 2014)

"Only skeletal muscle is under conscious control" yes that's what you'll read in any textbook, but it ain't necessarily so. The lower oesophageal sphincter is smooth muscle yet some people have it under conscious control, which allows them to make a living out of regurgitating light bulbs and stuff. Pretty gross if you ask me....

Oops, just reread your post & see that you made that point, however I still need to point out that skeletal muscles aren't always under conscious control, being part of a reflex arc makes some sense to me, after all I have limited control over my salivation & venom is probably just modified saliva.

Reflex arcs are fast and I reckon eminently suitable for the job.

There's no way to find out though & really does the subjective experience of a snake when it's biting you make any difference?

Also isn't the story of a keeper who got envemomated by a shed tooth / frozen snake just an urban myth?


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## Bluetongue1 (Feb 23, 2014)

Bluetongue1 said:


> Only skeletal muscle is under conscious control. Due to the complexities of our nervous system, it is on rare occasions possible for someone with an immense amount of specific training to exercise a measure of conscious over what is normally involuntary muscle. This is the exception to the rule, extremely rare and cannot be achieved by the vast majority who train to do so.


*Mikey*, I am not sure whether you are meaning to reiterate for emphasis or adding due to perceived omission???

Blue


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## Elapidae1 (Feb 23, 2014)

GBWhite said:


> It actually has two primary purposes. It's used to not only immobilise but to assist in the digestion of prey. It's basically a modification of saliva that's found in other vertebrae.
> 
> Humans and other mammals have the ability to chew their food where (as we all know) snake don't chew but swallow their prey whole.
> 
> ...



I was under the impression that venom serving to aid digestion had been disproved or at least while it may in its nature aid digestion in is merely coincidental and not necessary. The apparent health of Raymond Hosers venomoids would seem to verify this.


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## mikey_mike (Feb 23, 2014)

Elapidae1 said:


> I was under the impression that venom serving to aid digestion had been disproved or at least while it may in its nature aid digestion in is merely coincidental and not necessary. The apparent health of Raymond Hosers venomoids would seem to verify this.


Some venom aids digestion & some doesn't. You can tell by looking at the bite sites - some snakes give horrendous local reaction with digestion of tissue, whereas others just kill you (unless of course appropriate first aid is applied)

Bluetongue1 I'm not reiterating for emphasis, I'm just too lazy to read complete posts before responding. I'll reform my slovenly ways one day...


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## Elapidae1 (Feb 23, 2014)

The fact the tissue around some bites may break down is not proof that its design is to aid digestion.


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## -Peter (Feb 24, 2014)

Elapidae1 said:


> The fact the tissue around some bites may break down is not proof that its design is to aid digestion.


The fact that his venomoids are alive does not disprove it either. It merely means they are getting adequate nutrition. This could be because they have an increased diet. The fact that venom breaks down flesh does indeed prove that it aids digestion. That is what digestion is.


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## mikey_mike (Feb 25, 2014)

Elapidae1 said:


> The fact the tissue around some bites may break down is not proof that its design is to aid digestion.



Design? If you're suggesting that there's a designer there's no need to look for physical evidence, just consult the religious text of your choice,

Otherwise, the fact that some venom digests tissue at the bite site suggests that it has a role in digestion. I don't know how this could be any clearer.


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## GBWhite (Feb 25, 2014)

Hi Blue.

In reference to my post about venomous snakes closing the jaw to squeeze the venom out of the venom gland, it was merely an attempt to keep the explanation in as simple terms as possible so that the average punter has a chance to interpret the information provided.

It is true that your reference to page 15 of Rick's book explains that the masseter muscle attached to the rear of the venom gland contracts to squeeze the gland and force the venom through the deliver system but it does not explain the mechanics of how the masseter muscles operate. The same explanation in duplicated on pages 304 and 305 of "Herpetology: An Introductory Biology of Reptiles and Amphibians" Laurie J Vitt & Janalee P Caldwell. 

This muscle is only a thin membrane located underneath the venom gland. Does it work independently and is it able to be individually controlled by the snake? What mechanics actually cause the muscle to contract? Feel free to correct me if I'm wrong but I believe it just may be attached to other muscles that are connected with both the upper and lower jaws.

Vitt and Caldwell state that venomous snakes can also regulate the amount of venom delivered in a bite by contracting the adductor superficial muscle (connected at the rear of the venom gland) however; again there is no explanation of how the mechanics of an elapid snake bite works. 

Kenneth V Kardong's paper "Lateral Jaw and Throat Muscles of the Cottonmouth Snake" explains that along with the masseter muscles the adductor superficial muscles found in elpaid snakes are also instrumental in squeezing the rear of the venom gland to distribute it along the delivery system. These muscles are located at the junction on each side of the upper and lower jaw, and further explains that lateral jaw movement is controlled by the lower jaw. He states that the contraction of the "Modelius compressor grandulae muscle is implemented in venom ejection due to its close association with the venom gland but may likewise be partnered with other muscles in jaw closure".

To me this further suggest that it is highly likely the amount of pressure applied by the lower jaw at the time of a bite has a direct effect on the amount of venom delivered in a bite.

Now in saying all this and considering that elapids tend to either bite their intended victim/prey in a deliberate hard biting action and/or maintain a grip on same to inject sufficient quantities of venom to immobilize their prey it is more than likely a that a choice has been made by the snake to bite hard in such a situation and thus apply sufficient pressure on all the muscles mentioned to deliver the quantity of venom determined to immobilize and subsequently kill the item being bitten.

To me. whether this is a conscious choice to choose the amount of venom delivered or simply an act of instinct appears to be open to debate. 

I don't know about you but I have personally experienced both wet and dry bites from small Australian elapids as well as a dry bite from a Death Adder and full envenomation form a Red-bellied Black, Tiger Snake and Brown Snake. I can assure you that on each occasion when I have been envenomed I felt a notable difference in the amount of pressure applied by the snake's upper and lower jaws when it is a deliberate and intentional bite compared to when I have suffered a dry bites which (at least in my case) have always occurred where the snake has failed obtain contact with its bottom jaw.

So it would appear to me that it is a reasonable assumption that to add to all the other possibilities that may contribute to a dry bite, it may be possible that what I have outlined may just be another contributing factor to the discussion.

I reiterate that based on personal experience and from what I have read this is just my personal assumption of how a dry bite may occur.

George


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## andynic07 (Feb 25, 2014)

GBWhite said:


> Hi Blue.
> 
> In reference to my post about venomous snakes closing the jaw to squeeze the venom out of the venom gland, it was merely an attempt to keep the explanation in as simple terms as possible so that the average punter has a chance to interpret the information provided.
> 
> ...


Very interesting and informative post George. It sounds like the actual muscle flex isn't voluntary but actually driven by the amount of pressure delivered but this is actually in debate as to whether the pressure is deliberate or an instinct. I can see with the limited brain function of snakes bites being instinctual and the primal drive of the snake biting prey could overcome the snakes thoughts causing it to bite hard but also wonder if they are more intelligent than we give them credit for and they can actually differentiate between defensive bites and bites to kill.


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## DRoddy (Feb 26, 2014)

If venom delivery is not voluntary in any way...how do we explain the spitting species?

D


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## Elapidae1 (Feb 28, 2014)

Elapidae1 said:


> I was under the impression that venom serving to aid digestion had been disproved OR AT LEAST WHILE IT MAY IN ITS NATURE AID DIGESTION IN IS MERELY COINCIDENTAL AND NOT NECESSARY The apparent health of Raymond Hosers venomoids would seem to verify this.





Elapidae1 said:


> The fact the tissue around some bites may break down is not proof that its design is to aid digestion.





-Peter said:


> The fact that his venomoids are alive does not disprove it either. It merely means they are getting adequate nutrition. This could be because they have an increased diet. The fact that venom breaks down flesh does indeed prove that it aids digestion. That is what digestion is.



I would say it does disprove it, if the venom was necessary for digestion then surely you would have to expect complications of some form in the animals health if the venom were removed. as capitalised in my above post I recognise that it aids digestion I'm just saying it isn't necessary and/or its evolutionary function as GBWhite suggests




mikey_mike said:


> Design? If you're suggesting that there's a designer there's no need to look for physical evidence, just consult the religious text of your choice,
> 
> 
> 
> Otherwise, the fact that some venom digests tissue at the bite site suggests that it has a role in digestion. I don't know how this could be any clearer.


By design I mean its evolutionary purpose or "evolutionary design" whether you like my choice of words or not I think you knew what I meant.

That has always been clear. Again Im just saying that that particular role is unnecessary and not a Primary function as GBwhite suggests.
If it were a Primary function then why do venomoids function without it?


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## GeckoJosh (Mar 1, 2014)

Elapidae1 said:


> I would say it does disprove it, if the venom was necessary for digestion then surely you would have to expect complications of some form in the animals health if the venom were removed. as capitalised in my above post I recognise that it aids digestion I'm just saying it isn't necessary and/or its evolutionary function as GBWhite suggests
> 
> 
> 
> ...



Only a study feeding captive venomoids the average diet of their wild counterparts would prove the theory, I personally think its just as plausible to say that producing healthy captive specimens without the benefit of venom aided digestion could be attributed to the added nutrition of a stable dietary intake.

That being said my personal belief is that primary role of venom in at least most Australian species is to immobilize prey and that if venom was needed fro digestion then why have so many reptiles evolved without it?


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## GBWhite (Mar 1, 2014)

It amazes me how some people read posts.

First off I don't recall stating that venom is necessary or needed for the digestion of prey. 

I agree that it may not be necessary because snakes already have strong *natural digestive secretions*. If the post is read correctly it states that a primary function of venom *assists* with digestion of prey. It appears to assist by increasing the time taken for food to digest. 

Thomas & Pough (1979) found that injecting mice with Western Diamondback Rattlesnake (Crotalus atrox) venom before being fed to non-venomous snakes increased the rate of digestion. They found that the venom's proteolytic activity loosened hair and weakened the internal organs of prey resulting in the more rapid rupturing of the visceral cavity. This provided the *natural digestive secretions* of the snakes stomach a larger surface area to act on resulting in the faster digestion of prey.

Nicholson & colleagues (2006) found that the Australian Coastal Taipan (Oxyuranus scutellatus) venom increased the rate that soluble proteins were released and although the mechanism was not studied, suggested phospholiphase may play a role by disrupting cell membranes.

Nicholson, Mirtschin, Madaras, Venning & Kokkin (2006) revealed analysis of Australian Coastal Taipan venom increased the rate that proteins were released suggesting the potential importance of envenomation in the digestion of whole prey.

Reichert (1936) found that envenomated prey ingested by the Brazilian Jararacussu (Bothrops jararacussu) was digested over 4 to 5 days whereas where non-envenomated prey was ingested the process took between 12 to 14 days.

Zeller (1948 found similar results in Asp Viper (Vipera aspis) where envemonated prey took 3 days to digest whereas non-envenomated prey took between 5 & 8 days.

Cheers,

George.


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## -Peter (Mar 1, 2014)

All cats are gray in the dark...


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## longqi (Mar 1, 2014)

DRoddy said:


> If venom delivery is not voluntary in any way...how do we explain the spitting species?
> 
> D



Very good point
Even with various spitting cobra species there is a huge range of difference in both accuracy and amount of venom used
Javans are deadly accurate even when only a few months old
Baby Javans are cool to watch... They peel their lip back but nothing happens
Equatorials are much less accurate and appear to dribble a lot more out


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## Elapidae1 (Mar 1, 2014)

My apologies for misreading your post George and then exacerbating the conversation further with my own difficulty at explaining myself in writing. 
Unfortunately the nature of forums means members are from varying levels of experience, understanding of reptiles and ability with written English. Rather than being argumentative I was just hoping to stimulate conversation and information sharing on a subject I like. Unfortunately due to misinterpretation and/or Mikey-Mikes condescending I'm right your wrong attitude i felt the need to defend my opinion and understanding of the subject

I took your use of the word "primary" (first in line of importance) as meaning necessary.

Maybe in the wild the increased speed of digestion is a necessary function in order to decrease the time spent vulnerable to predation, whereas captive venomoids don't have this to contend with and therefore function quite well without it.

Thanks for taking the time to reference some studies.

Cats change colour to suit there environment?


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## -Peter (Mar 1, 2014)

All cats are grey in the dark refers to the evidence one see with ones own eyes and accepts as fact, Thus without light to see them properly they are grey but if you look at the subject properly you find evidence otherwise. Basically, what you see is not always the truth.


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## GBWhite (Mar 1, 2014)

DRoddy said:


> If venom delivery is not voluntary in any way...how do we explain the spitting species?
> 
> D



G'day my friend.

I should begin by explaining that (as pointed out in a previous thread) the reptilian brain supersedes the human brain by about 200 million years. It is the core for the human and other mammal and bird brains to develop to their present levels but unlike mammals and birds has not developed further since that time.

I've done a little digging around and from what I've read to date have come to the conclusion that "spitting" venom is not a conscious act in Cobras. I'm not saying anyone else is wrong. This is my personal conclusion after investigating a number of papers and articles. As always I encourage others opinions. 

I've come to this conclusion based on:

The human brain consists of three distinct brains that have developed over time through evolution to co-inhabit the modern human scull.

These three separate brains are the;

1. Reptilian brain - Oldest and responsible for autonomic functions such as heart beat and breathing, body temperature, flight and fight response, survival. of instinct. It first appeared in fish
about 500 million years ago and went on to develop to it's most advanced stage in reptiles around 200
million years ago. It appears to have not evolved to recognise conscious thought. 

2. Limbic brain - This evolved in the first mammals around 150 million years ago and basically records memories of
behaviour and is responsible for the future development of emotions

3. Niocortex - Appeared and began it's expansion in primates about 3 million years ago. It plays the dominant role 
responsible for human language, abstract thought and *conscious thought*. 


My understanding is that Cobra's that are capable of spitting do this as a defensive reaction. The defensive reaction is a subconscious thought activated in the amygdala which is situated at the top of the brain stem. It is linked to fear responses and allows animals to react almost instantaneously to the presence of danger without thinking.

I'm open to discussion but I don't believe it has anything to do with subduing prey; ie Do they use it as a means to capture and subdue prey before ingestion? Maybe someone who has witnessed this in the field or captivity can enlighten me further if this is is the case.

From what I understand; by all definition a defensive reaction is a subconscious act that has nothing to do with thinking and cannot be controlled. Conscious thought is when a situation summed up and a decision is made.

From what I have read I'm under the impression it has been established that the mechanics of the spitting action is directly linked to the mechanics of injecting venom and if selected species of Cobra's only use the "spitting action" as a means of defence, in all consideration it is more than probable that this is an instinctive and unconscious act.

George


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## montay (Mar 1, 2014)

Yes, this is true from a biological perspective - although venom is simply modified saliva, a snake will only pump as much venom as it needs to. You know the old saying that a snaked produces enough toxin in 1 ml of venom to kill so many hundred/thousand rats? The reason they don't pump that amount of venom into one singular rat is because it is made to order and they generally won't waste venom if they are warding off something that they don't plan to eat. Hence why some snakes hit like machine guns, they means business.

Best to treat all venomous snake bites as though you have been envenomated.



Bushman said:


> Good question mate and one that I've wondered about myself.
> My thoughts are that because venom is a biologically expensive product to make, that they don't waste it unnecessarily and they will often send out warning shots first.


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## mikey_mike (Mar 1, 2014)

This has been a most informative thread.

One final comment - wrt spitting venom requiring conscious effort - I've met people who spit without any apparent conscious decision to do so. 

Also, I think most of us have worked out that we can activate a reflex in our mouth & spray saliva - surely I'm not the only one who's noticed this.


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## DRoddy (Mar 2, 2014)

If you have kept spitting Cobras before... you will know that it is a defensive reaction that can be executed at anytime the animal see's fit. 

If it can be executed anytime the animal see's fit, it is a conscious reaction.

For instance, they won't spray venom at your back if you walk up to on with your back to them. Turn around and they can see your eyes, they spray venom.....a conscious reaction to threat.

D


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## cement (Mar 2, 2014)

So is the snake thinking "i'll wait till he turns around"..., or is it just so scared by seeing the eyes and face of a large predator that the jolt of fear causes the spit reaction?


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## DRoddy (Mar 2, 2014)

You could say that....esp if you haven't kept them. 

If you _have_ kept a spitting species before.... then you will know that they are perfectly able to "decide" when is the best time to "defend" themselves.

If they weren't, it would be different type of defense displayed....wildly spitting at every perceived threat. They don't do that. They are perfectly able to pick and chose their shots.


Cheers,
D


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## cement (Mar 2, 2014)

Nope, definatly never kept spitting cobras. Just a question buddy.. I would love to be able to then I would be able to see for myself, but I live in Australia.


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## DRoddy (Mar 2, 2014)

It's all good brother, just speaking from experience with them.....that's all.

D


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## longqi (Mar 2, 2014)

cement said:


> So is the snake thinking "i'll wait till he turns around"..., or is it just so scared by seeing the eyes and face of a large predator that the jolt of fear causes the spit reaction?



It is definitely a defensive action
Notice I used action rather than reaction [more bout that later]

Any adult Naja sputatrix can definitely decide exactly how when and how much venom it will spit
If it was simply a defensive reaction the result would be similar any time it felt threatened
They spit from any position often before even raising their hood

Right now we have 3 large adults and about 10 smaller ones
One large adult sprayed like crazy when I caught it a week ago
Now it hoods up and turns the lip back but doesnt spray until I really stir it up
Second adult sprays as soon as you open the box
Third adult doesnt even turn the lip back

All were put under similar threat by me tonight to watch any differences
If it had been defensive reaction all would have reacted in a similar fashion to the same perceived threat??
That is why I think it it is best described as defensive action


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## NicG (Mar 2, 2014)

GBWhite said:


> G'day my friend.
> 
> I should begin by explaining that (as pointed out in a previous thread) the reptilian brain supersedes the human brain by about 200 million years. It is the core for the human and other mammal and bird brains to develop to their present levels but unlike mammals and birds has not developed further since that time.
> 
> ...



Following on from this, and getting back to the original question, can some/all elapids (especially Australian) decide between two actions - a defensive dry bite and a food-related envenomation?


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## GBWhite (Mar 2, 2014)

Hi Nic,

I do keep snakes including Australian vens and have maintained, studied and collected many varied species of these throughout the years and as a result my particular interest these days evolves around reptile physiology.

In my initial post on this thread I stated that I did not know if snakes can deliberately/intentionally choose to inject venom. Further posts by others triggered my ever inquiring mind and I set off (as I tend to do) to investigate the topic. 

So, over the past 6 or 7 days I have spent considerable time reading quite a number of scientific papers, articles & reptile publications related to reptile physiology, the venom delivery system, mechanics of delivery, the reptilian, animal and primate brains then combined all this information with personal experience and observation as well as considered all what has been posted on this thread. 

As a result I haven't uncovered or been convinced by any evidence to date to confirm to me that snakes, including elapids, are capable of making a conscious choice to deliver venom or a dry bite. 

No doubt there are others that oppose this view and if they can provide positive hard evidence to back their argument I'm open and encourage discussion with the possibility of changing my mind. 

I'm not saying anyone is wrong and I'm not saying I am right. I'll leave that judgement up to others. I respect the opinions and information offered. I also recognise some opinions may differ. This is just my personal conclusion based on the evidence presented and that which I have uncovered.

I recognise that Peter (Longqi) & DRoddy have personal experience with Spitting Cobras and both have contributed by informing that "spitting" venom is used as a means of defence. However; the information they have posted, regarding the action as being a conscious act, seems to me, to be only based on assumption. Personally, I don't find enough hard, clear and precise evidence provided in their posts to back up their conclusion that venom delivery (or in the case of some Cobras, ejection) is a conscious choice. 

Albeit from personal experience with collecting vens I learnt many years ago that to have any chance of catching them in open situations, the last thing you want to do is make eye contact. This is because as soon as eye contact is made they become instinctively aware of the possibility of threat and as a result act instinctively (subconsciously, without thought) with a flight or fight response. What DRoddy mentioned about being able to walk up to "spitters" with your back turned and the "spitters" not reacting until eye contact is made appears to me to be conducive with a natural, instinctive (subconscious), defensive response.

From my experience, captive situations regarding snakes defensive reactions differ quite a great deal to those encountered in the wild. I am aware that due to many variables, even recently caught and held snakes can display different defensive reactions within a short period of captivity and personally do not consider captive defensive reactions creditable enough as evidence to confirm that a defensive reaction under these conditions is a genuine conscious choice. 

The main contributing factors to my conclusion are based on evidence obtained in the form of scientific literature/publications, personal observations, personal experience and discussions with associates. 

All this information combined leads me to the conclusion that snakes are a primitive animal with a very small primitive brain and do not possess the ability to recognise conscious thought. 

Therefore, I'm going with the negative and saying. No...They can not decide between two actions - a defensive dry bite and a food related envenomation.

Again I reiterate that this is my personal conclusion based on evidence uncovered/obtained.

So I'll leave it up to you and others to come to their own conclusion.

Cheers,

George.


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## longqi (Mar 3, 2014)

I have a feeling that one day in the future science will change its mind about reptilian brains/intelligence

Rinjals [sic] from Southern Africa play dead
Yet they only play dead with some predators

Some Iguanas solve food or escape related puzzles

We are only starting to scratch the surface in learning about reptiles
We may have a lot to learn

- - - Updated - - -

Feeding cobras kraits and vipers tonight

result
100% envenomation
Types of bite
Krait x2 bit and held on
Cobra 3 bit and held on
5 bit and immediately released [no lower jaw contact visible]
Vipers
1 bit and chewed before releasing
2 bit and immediately released

In all cases except the kraits the victims were dead or dying before consumption
Kraits both bit multiple times and chowed down immediately 

IMO all the bites contained venom because of the reaction of the prey items

Statistics
13 snakes
13 bites
13 probable envenomations

Question
If snakes cannot control their venom input why would it appear that in this case 13 bites resulted in 13 envenomations, while if those bites had been into humans scientific fact shows that the rate of envenomation would be around 50%-+??


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## Bluetongue1 (Mar 7, 2014)

*George*, 

The *amygdala* is part of the Limbic System and according to the 3-brain model you espoused is therefore NOT part of the reptilian brain. So what is it doing in a Cobra’s head? 
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The 3-part brain model you expounded is known as the Triune Brain was proposed by the American physician and neuroscientist Paul D. MacLean in the 1960s. It was hypothesised by MacLean to explain the evolution of the vertebrate forebrain and related behaviours. It was popularised through inclusion in a Pulitzer Prize winning book but gained very limited academic support, especially with comparative neuroscientists.

From the late 1980s on, advances in techniques that allowed the mapping of neurotransmissions in the brains of animals, revealed that the basis of MacLean’s hypothesis was incorrect. The basal ganglia structures from which MacLean’s reptilian brain were derived have been shown to exist in amphibians and fish as well i.e. they are present in all extant vertebrates which pushes the origin back to a common vertebrate ancestor more than 500 million years ago. This has further been supported by strong recent evidence that the neocortex was already present in the earliest mammals and that a homologous structure derived from the same tissues and with similar connections within the telencephalon, like those made by the neocortex, exist in reptiles and birds.
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Striated muscle is under voluntary control. It involves nerve pathways which involve the cerebrum. 
You need to look up the nerve pathways involved in a reflex arc. 
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*From:* Davidson College, Davidson, North Carolina US - Animal Physiology Class. (The college has graduated 23 Rhodes Scholars)
*Excerpt: *Rattlesnakes are also known to alter their behaviour according to the prey type, holding onto prey that are more mobile (birds) while releasing prey (mice) that may be easily located using the chemosensory system even if they are allowed to travel after being envenomated (Hayes, 1992a).

*From:* Miami University, Oxford, Ohio US - Anatomy of Venomous Snakes notes
*Excerpt:*The accessory gland was noted by Mitchell to prevent wasteful flow of the secretions. This gland lacks smooth muscle and is strictly regulated by striated muscle. Implications are that the accessory gland is under voluntary control and that snakes can and do control the amount of venom that is released during a bite. 

*From: *Handbook of Venoms and Toxins of Reptiles
*Excerpt:* [p75-p76] The venom glands. of viperids (Kardong and Lavin-Murcio, 1993), elapids (Rosenberg, 1967), and atractaspidids (Kochva, 2002) are part of high-pressure delivery systems. The venom bolus is quickly expelled; rattlesnakes can deliver venom in less than half a second (Kardong and Bels, 1998). Although the specific gland compressor is different in each family (Jackson, 2003), all of these venom systems exhibit notably direct striated muscle insertion. When the gland compressor muscle contracts, the main venom gland is pressurized, producing expulsion of a presynthesized, stored, venom bolus. From venom gland to exit orifice at the tip of the tubular fang, this system is closed when activated, not open to ambient pressures, and therefore can develop, under striated muscle action, a sustained high-pressure head until venom enters the prey or predator (cf. Rosenberg, 1967). 

*From: *Young et al. Functional Bases of the Spatial Dispersal of Venom during Cobra “Spitting”. Physiological and Biochemical Zoology, 2009; 82 (1): 80 DOI: 10.1086/595589 
*Excerpt:* The name "spitting cobra" is a bit of a misnomer. Cobras don't actually "spit" venom, says the study's lead author Bruce Young, director of the Anatomical Laboratory in the Department of Physical Therapy at the University of Massachusetts, Lowell. Muscle contractions squeeze the cobra's venom gland, forcing venom to stream out of the snake's fangs. .

*From: *The Journal of Experimental Biology 213, 1797-1802 © 2010. Published by The Company of Biologists Ltd
doi:10.1242/jeb.037135. *Target tracking during venom ‘spitting’ by cobras. *Guido Westhoff1, Melissa Boetig2, Horst Bleckmann1 and Bruce A. Young3,* 1 University of Bonn, Germany, 2 Washburn University, Topeka, KS USA and 3University of Massachusetts Lowell, MA USA *Author for correspondence ([email protected]).
*Excerpt: *In the present study we show that spitting cobras can accurately track the movements of a potentially threatening vertebrate, and by anticipating its subsequent (short-term) movements direct their venom to maximize the likelihood of striking the target’s eye. Unlike other animals that project material, in spitting cobras the discharge orifice (the fang) is relatively fixed so directing the venom stream requires rapid movements of the entire head. The cobra’s ability to track and anticipate the target’s movement, and to perform rapid cephalic oscillations that coordinate with the target’s movements suggest a level of neural processing that has not been attributed to snakes, or other reptiles, previously. [Take note Longqi]

*From: *Venom flow in rattlesnakes: mechanics and metering. Bruce A. Young* and Krista Zahn. _Department of Biology and Program in Neuroscience, Lafayette College, Easton, PA 18042, USA. Accepted 28 September 2001_
*Excerpt:* The functional morphology of venom injection in Crotalus atrox was explored using high-speed digital videography combined with direct recording of venom flow using perivascular flow probes. Although venom flow was variable, in most strikes the onset of venom flow was coincidental with fang penetration, and retrograde flow (venom suction) was observed prior to fang withdrawal. The duration of venom flow was consistently less than the duration of fang penetration. The occurrence of retrograde flow, ‘dry bites’ (which accounted for 35 % of the strikes) and unilateral strikes all support a hypothesis for venom pooling in the distal portion of the venom delivery system. No significant difference in temporal or volumetric aspects of venom flow were found between defensive strikes directed at small and large rodents. With the species and size of target held constant, the duration of venom flow, maximum venom flow rate and total venom volume were all significantly lower in predatory than in defensive strikes.
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To say venom has "two primary purposes" is not quite correct. This indicates that either both are of equal importance in their functions or that both are fundamental in what they do. A venomous snake can digest prey that has not been envenomated, so clearly assisting digestion is not a fundamental function if it can be done without. In terms of importance, procuring a meal in the first place is more important than gaining assistance with its digestion. You cannot digest a meal that you have been unable to procure.

I suspect that nearly all venoms provide some assistance to digestion but this varies from minimal, as would seem to be the case with our Australian elapids, to significant with many of the Viperidae, in particular those with strongly cytotoxic venom. 

I also think it important to add “defence” to the list of functions. 
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I stopped researching because I had too much material. As it is I have only used a portion of what I did collect due to length. The information is out there and accessible – there is no question about that. 
I don’t think I can convince you of anything. I am simply putting some hard data on the table for you to consider if you so wish. If it still clashes with your schema then it is only sensible that we agree to disagree and leave it at that.

Blue


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## GBWhite (Mar 12, 2014)

Hi Blue,

G’day my friend. After reading your post I couldn’t just “leave it at that” and considering what you’ve written I’ve decided it deserves a response.

It appears to me that what I have posted just may clash with your schema. So, like you state we’ll just have to agree to disagree.

You seem to have gone to a lot of trouble to access the information you posted but I was wondering if you realize the question posed is “Dry bites – are they a *conscious thought* or just a lottery?”

As well as having a life long interest in herpetology (extending just shy of 50 years) my job as a private investigator involves providing lawyers and barristers with hard unbiased evidence, which amongst other things includes examining and reporting on scientific documentation. This is to assist them in cases regarding very complex matters. This process involves having an open mind and searching “outside the box”.

Since your last post I have undertaken further research with the aim to find discussion regarding conscious thought in snakes and it appears that very minimal (if any) has been published directly related to the topic. So I don’t know where all the alleged “hard data” you researched is located. I have not found any evidence anywhere to confirm to me a relationship between conscious thought and dry bites in snakes. Albeit I haven’t uncovered any evidence to confirm or deny if snakes are capable of any sort of conscious thought.

Your post infers that the Basal ganglia are directly related to conscious thought in snakes. I don’t see this as the case.

The R-comples: The reptilian Brain – Basal ganglia and Thalamus
Psycheducation.org

_These are the oldest parts of the brain: the ones that we share with reptiles and birds. They are thought to be the location of basic drives and instincts, basic needs and avoidances._

To explain it simply – It is the base of the building blocks used in the development of other animal brains.

What I have discovered is that there are many skills associated with the survival in all animals. Many of these skills are derived through environmental stimulus. Conscious thought is not a skill necessary for the survival of snakes.

FYI Hard data confirms a fact. Hard data regarding conscious thought in reptiles would either state that they do or don’t have the capability of conscious thought.

I suspect that following the intense research you have undertaken you have selected what you consider to be the most appropriate relevant informative options to make your case but unfortunately there is nothing contained to confirm or deny to me that snakes are capable of conscious thought. 

Even the Abstract you copied and pasted from “Target Tracking During Venom Spitting by Cobras” (which by the way I accessed and read before posting my conclusion) only states that “cephalic oscillations that coordinate with the target’s movements suggest a level of neural processing that has not been attributed to snakes, or other reptiles, previously”. 

Neurons are nerve cells that individually serve a simple function of processing and transmitting information. When the nerve cells transmit and process in clusters they called a neural network,

I suppose it’s how one interprets the term “neural processing”. 

In regard to the above case. Does it infer the possibility of a conscious thought process? Or does it refer to the subconscious neural processing of stimuli received through sensory organs (sight, smell, heat) as is used by snakes to judge strike distance? The cephalic isolations immediately prior to “spitting” suggest to me it is more likely the later. I don’t see anywhere in the paper where the author describes it as a conscious act.

Voluntary control relating to skeletal muscle action in snakes is not hard data regarding conscious thought. The term “voluntary control” can be misleading considering voluntary muscle actions/reactions in vertebrates (including snakes) can be a subconscious act. For example;

Ceoccp.oxfordjournals.org
Skeletal Muscle Physiology
P. M. Hopkins – Professor of Anaesthesia

Extract – 

_The skeletal muscles are the effector organs of the locomotor system. They are under voluntary control, although much of their activity is *subconsciously* regulated. Skeletal muscle and cardiac muscle are both described as striated muscle because of their striped microscopic appearance. This appearance results from the ordered and regular arrangement of the sub-cellular contractile elements. Unlike cardiac muscle, skeletal muscle has no intrinsic spontaneous activity because it lacks the ion channels responsible for spontaneous membrane depolarization. Therefore, *the stimulus for physiological skeletal muscle activity is always derived from a nerve impulse*. The great majority of skeletal muscle fibres receive their nerve inputs at single central swellings of the fibres known as motor endplates._

It’s a term regularly used to describe reactions to some sensory stimulation where nervous impulses send messages to muscles faster than the brain can react. All material I have read to date indicates to me that it is a subconscious act related to bite reaction and venom control.

I don’t need to look up the nerve pathways involved in a reflex arc. 

Before I posted my conclusion I already new about the subject. 

A reflex action is a *subconscious "nervous" reaction that cannot be controlled*. It requires a stimulus to get a response. *It occurs without thinking*. Again, it’s a sensory stimulation where nervous impulses send messages to muscles faster than the brain can react. 

Here’s an excerpt taken from csmbio.csm.jmu.ed/biology/danie2jc/reflex.htm that I often refer to friends regarding vertebrae muscle reflex and the reflex arc.

Reflexes – Background. 

_A *reflex* is a response to a perturbing stimulus that acts to return the body to homeostasis. This may be subconscious as in the regulation of blood sugar by the pancreatic hormones, may be somewhat noticeable as in shivering in response to a drop in body temperature; or may be quite obvious as in stepping on a nail and immediately withdrawing your foot. _
_A_ *reflex arc* _refers to the neural pathway that a nerve impulse follows. The reflex arc typically consists of five components (3): _
_1. The _*receptor* _at the end of a sensory neuron reacts to a stimulus._
_2. The _*sensory (afferent) neuron* _conducts nerve impulses along an afferent pathway towards the central nervous system (CNS)._
_3. The _*integration center *_consists of one or more synapses in the CNS._
_4. A _*motor (efferent) neuron* _conducts a nerve impulse along an efferent pathway from the integration center to an effector._
5. An *effector* responds to the efferent impulses by contracting (if the effector is a muscle fiber) or secreting a product (if the effector is a gland)
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I concede that technically you are correct with your definition of the word primary. Your analogy regarding procuring prey may be consistent with front fanged advanced snakes. But … How do we describe the primary function of venom in rear fanged genera where venom plays no significant role in prey capture or defence? 
------------------------------------------------------------------------------------------
From what I’ve read about elapid venoms I disagree that it only provides minimal assistance in the digestion of food.
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Just to finish up;

You are correct that the amygdala is situated in the Limbic brain and not present in the reptile brain. There was a lot more discussion in that paragraph relating to defensive reactions in mammals compared to defensive reactions in snakes than was posted. I thought I had removed it and it wasn't until I read you comment that I realised I hadn't deleted the lot. Thanks for pointing that out. I apologise to all for any confusion I may have caused.

I can assure you that I am opened minded and capable of adapting and changing my thoughts and beliefs if I can locate or be provided with information to inspire me to do so. I think I stated this in a previous post. Unfortunately this is not the case with what you have provided. I’ll add that I don’t deliberately focus on references that support or confirm my pre-existing beliefs and ideas. 


George.


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## longqi (Mar 19, 2014)

GBWhite said:


> ------------------------------------------------------------------------------------------
> I concede that technically you are correct with your definition of the word primary. Your analogy regarding procuring prey may be consistent with front fanged advanced snakes. But … How do we describe the primary function of venom in rear fanged genera where venom plays no significant role in prey capture or defence?
> ------------------------------------------------------------------------------------------
> George.



I have only considered one part of this as something I can possibly answer
Primary function of some rear fanged snakes is definitely prey capture

Sea snakes use venom to subdue large prey
I have watched banded sea kraits and olive sea snakes hunting moray eels
If the eel is small they bite, hang on and almost immediately start eating
If the prey is large they bite near the head then bite down the body several times
Then they sit back and watch and follow waiting for the venom to take effect

Malayan kraits, bungarus candidus, front fanged elapids. Do exactly the same thing with other snakes before eating them
But they dont do the same thing with lizards

I would be really interested in a discussion about why so many human bites are dry while prey item bites appear to be usually wet
Surely that alone suggests that some thought is involved??


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