Do you talk about Hognose Snakes in venomous??

[rocketjawa]

Heya!!
I just sort of discovered this interesting little snake :)
Very cool.. neat personality.. Agressive until you get too close, then plays dead ;)

I was wondering if anyone has one here.. I like how they mimic Cobras.. do any species do it more that others/ look more cobra like??

I think an aldino one of these may satisfy my cobra craving .. so far, the only cobras I bought were for my GI Joe figure collection... yo joe!

[psilocybe]

Heterdon sp. are pretty cool snakes...
There seems to be a lot of controversy in the venomous community on whether they are "venomous" in the true sense of the word or not...different people will give you different opinions.

My opinion, yes they are, though they are basically harmless. I do remember reading of an "envenomation" that resulted in some good swelling, but even that is rare and the likelihood of a serious event happening due to a bite (considering they hardly ever bite) is next to nil.

A lot of people call them "puff adders" because of their defensive display (prior to playing dead of course), but some people might relate them to cobras because they flatten their necks when disturbed, resmembling a pseudo hood.

There are a few species that can resemble cobras, false water cobras (Hydrodynastes gigas) being most notable. They will spread a hood, but do not stand up...

http://www.snakemuseum.com/photos/WaterCobra1s.jpg

They are rear-fanged venomous, and though some people have reported painful bites, are generally inoffensive and not considered too serious at all. They still warrant the same respect you would give any other rear-fanged snake though.

[rwg]

Hognoses generally get discussed in the colubrid forum. They are technically venomous, but are not often refered to as "hot". False Water Cobras seem to be about where the line gets drawn. As far as I understand their evolution, neither actually "mimics" cobras since cobras and FWC/hognoses dont live in the same part of the world. My guess is that making yourself look big is a successfull defensive tactic that developed independantly in different species.

Oh, FWCs get absolutely huge...in a recent thread they were listed as the world's heaviest colubrids.

rg

[psilocybe]

Rwg is correct, it is unlikely that fwc's mimic cobras, since they don't occur in the same regions, or even the same continents. I was in no way trying to insinuate that they were mimics.

As for size, yes, they can get up to about 8 ft, but 6-7 is usually more common. They are also pretty bulky, though I can't say for sure whether they really are the "heaviest colubrid".

Secondly, their feeding response borders on psychotic...if you get one of these guys, be careful during dinner time!

[JD@reptiles]

This debate is going to go on for ever. When it comes to western hognose's being venomous i personally think it is just a strong coagulant, and nothing more. If that’s the case I guess most snakes would be venomous by your meanings. I really want to dissect a dead hognose and see if I can pull up and venom glands. One thing I've seen from owning hognose snakes they do have enlarged back teeth. From what books I have read, the soul purpose of those teeth are to pop toads and frogs.

I'm not trying to tell anyone they are wrong. just what i think.

Take care

Jordan

[BWSmith]

Many snakes are venomous. Just not everything that is venomous is dangerous to humans. Hognose are a great example. Asian ratsnakes are another. That cute little Beauty Snake has cobra three-finger- toxins and alphaneurotoxins, if memory serves. But is it dangerous to humans, probably not. Not unless you are allergic. After all, I recently had a bad reaction to a Garter Snake bite but I can roll in Poison Ivy all day long and I am fine.

Just some random thoughts before my first cup of coffee.

[psilocybe]

B.W. is citing some good information. Though some (Seamus) would disagree. Ongoing research by Dr. Bryan Fry and Wolfgang Wuster (among others) has produced evidence that ALL "colubrids" are venomous so to speak, with the exception of a few North American Genera (i.e. Elaphe, Pituophis, Lampropeltis, etc.). It is true that "three finger toxins", commonly found in most elapids is present in supposedly "non-venomous colubrids". This does not mean that all these newly discovered "hots" are dangerous, but supposedly "harmless" species have caused fatalities in the past, i.e Boomslangs, Rhabdophis sp. , Thelatornis, etc. Dr. Fry estimates that there is at least 1 dangerous species of "colubrid" within each of the families in Colubridae. Time will tell I suppose.

[JD@reptiles]

doesn;t a snake need venomglands and fangs to be truely "venomous"? i mean, if thats not the case, i am sure boas and pythons got some nasty stuff in there saliava which would make them venomous too? along with monitors and other lizards? i have been bit by asian rat snakes and never had any effects. i have read about the colubrid 3FTx that isn't injected through fangs and glands, right? like, what makes a snake venomous?!

[Dr. Bryan Fry]

Hi mate

The fangs aren't the defining characteristic but rather the presense of a venom gland. The venom gland in the colubrid snakes is the exact same one found in the atractaspidids, elapids and viperids (which is why the term Duvernoy's gland has been abandoned). However, there is a remarkable difference between being venomous and being dangerous. The Asian ratsnakes for example put out enough venom to settle a frog down but not enough or efficiently enough to affect humans. They deliver it via the wounds caused by the numerous sharp teeth. In other species the glands or teeth may be much more enlarged and this increases the relative danger. Its ultimately down to how much of the venom is delivered and how toxic it is.

So, hognosed are venomous but they certainly aren't dangerous so should be considered as 'harmless' for legislative purposes.

Cheers ;-)
Bryan

[BWSmith]

for legislative purposes.

Very nice.

[Samba]

I've really enjoyed this thread, being a hognosed enthusiast. I've never been bitten by one, so I wouldn't be able to tell you what it's like, but they are technically referred to as rear-fanged snakes. I consider snakes to be venomous when they have specialized glands and fangs to distribute it with.

Hogs are great snakes to keep, although if you want to observe some of their behaviours you might be better off observing a wild snake. The captive-born hogs that I had were far too accustomed to humans to really fear them. Or, on second thought, get babies, as they are defensive and may 'perform' for you. =)

[M_surinamensis]

This thread came up in a search on what was really an unrelated topic... But since I ended up reading it (hey, only... seven... months late) I figured I'd post this link (http://thereptileroom.org/forum/index.php?showtopic=57&hl=heterodon) which has a pretty decent (albeit typo ridden) summary of the objections I have to calling heterodon "venomous." I could just copy and paste the responses, but they were made conversationally and taken out of context make a lot less sense.

[Dr. Bryan Fry]

Hi Seamus,

I read with interest the very long thread on that link. Can you please justify the statements that the colubrids don't have a delivery mechanism?

You seem to require delivery to be an essential part of being venomous. Fair enough. At no point did we say that venom existed without a means to deliver it. What we pointed out was that venom predated advanced delivery architecture in the form of high pressure system based upon intricate muscle arrangements in proximity to hollow venom glands, terminating in hollow, hypodermic fangs.

However, this isn't the only means of venom delivery, simply the most refined. The ancestral form of the venom gland dumps the venom over the maxillary teeth. Even without being greatly enlarged, these teeth are sufficient to break the skin, and thus provide a route of entry for the venom. For feeding on soft-skinned prey like frogs or geckos, this is more than sufficient armament.

As to the ancestral venom being utilised for predigestion rather than prey capture, and thus not being a true venom, this overlooks the biochemical characteristics of the ancient venom. Particularly the presense of enzymatically inert, potent neurotoxins. Neurotoxins have one function and one function only, to kill. They cannot lubricate and cannot break down tissue.

In the case of Heterodon, the rear teeth are greatly enlarged, thus increasing the venom delivery efficacy considerably.

Cheers
Bryan

[M_surinamensis]

I suppose it's a matter of degree- the rear teeth in heterodon aren't particularly close to the duct openings, pressure on them doesn't release any greater concentration of the toxins than pressure elsewhere in the mouth and given that the toxins are suspended in saliva... again, the concentrations aren't stronger along those rear teeth. Given that, every tooth in a heterodon's mouth is equally capable of acting as a delivery system and since a traditional definition would not allow that as specific delivery apparatus... they are non-venomous.

If evolutionary pressures follow the logical route and push everything where it needs to be so that the ducts open to pour the toxins along those rear teeth or where pressure on the teeth directly causes a fresh flow... Then they have a delivery system and the required toxins and meet the qualifications.

The problem is larger than just snakes though; which is where I suspect you'll run into trouble by using the term venomous for animals meeting only half the definition. It's a term used in pretty much every other branch of zoology as well as botany. Offhand I can't remember if there are any bacteria that qualify but there may be an issue there too. Start blurring the lines about what constitutes a specialized adaptation for delivering the toxins and the term becomes meaningless and generalized.

The heterodon are also just an often debated example of the issue though, in one of the .pdf versions of the writeups you had done centered on the analysis of the compounds as found even in colubrids considered totally nonvenomous, the compounds themselves were repeatedly called "venoms." I am aware and appreciative of the fact that care was taken to distinguish between clinically signifigant venoms and the near negligible amounts which were identified in say... asian Elaphe but many of the people reading it and then taking it to discussion forums were apparantly unable to make the distinction. Had a different term been used to describe species in which the toxins were found but the delivery system was absent (in the case of the heterodon, I think it's groundwork on an evolutionary scale that doesn't *quite* meet the requirements) then for the herpetocultural community... it would have been better understood and better reccieved. As I think I noted in the linked thread... I wouldn't care if they were called Fryomous- just something that distinguishes them from species which have a delivery method.

There may be some debate over a few species in which the delivery system is particularly rudimentary... protovenomous versus prevenomous but when looking at the potential biological specializations associated with commonly accepted rear fanged venomous colubrids- heterodon don't quite clear the bar.

[Dr. Bryan Fry]

>I suppose it's a matter of degree- the rear teeth in heterodon aren't particularly close to the duct openings

Have you ever actually investigated the system? The ducts are directly above the enlarged maxillary teeth

>, pressure on them doesn't release any greater concentration of the toxins than pressure elsewhere in the mouth

Actually the chewing does push the toxins out in a pressure driven manner

> and given that the toxins are suspended in saliva
... again, the concentrations aren't stronger along those rear teeth.

Actually, the concentration is going to be highest right at the point of contact with the enlarged maxillary teeth.

>Given that, every tooth in a heterodon's mouth is equally capable of acting as a delivery system and since a traditional definition would not allow that as specific delivery apparatus... they are non-venomous.

I think you have misunderstood the concept of venom delivery mechanism. The key point is that the snakes need to be able to break the skin to facilitate the delivery of venom. That is all.



> If evolutionary pressures follow the logical route and push everything where it needs to be so that the ducts open to pour the toxins along those rear teeth or where pressure on the teeth directly causes a fresh flow... Then they have a delivery system and the required toxins and meet the qualifications.

There we go then. They are venomous.

> The problem is larger than just snakes though; which is where I suspect you'll run into trouble by using the term venomous for animals meeting only half the definition.

They have met the full definition: they produce specialized toxins for the sole purpose of disrupting the physiological system of whatever is being bitten and they are able to deliver it into said animal.

>It's a term used in pretty much every other branch of zoology as well as botany. Offhand I can't remember if there are any bacteria that qualify but there may be an issue there too. Start blurring the lines about what constitutes a specialized adaptation for delivering the toxins and the term becomes meaningless and generalized.

> The heterodon are also just an often debated example of the issue though, in one of the .pdf versions of the writeups you had done centered on the analysis of the compounds as found even in colubrids considered totally nonvenomous, the compounds themselves were repeatedly called "venoms." I am aware and appreciative of the fact that care was taken to distinguish between clinically signifigant venoms and the near negligible amounts which were identified in say... asian Elaphe but many of the people reading it and then taking it to discussion forums were apparantly unable to make the distinction. Had a different term been used to describe species in which the toxins were found but the delivery system was absent (in the case of the heterodon, I think it's groundwork on an evolutionary scale that doesn't *quite* meet the requirements) then for the herpetocultural community... it would have been better understood and better reccieved. As I think I noted in the linked thread... I wouldn't care if they were called Fryomous- just something that distinguishes them from species which have a delivery method.

They are fully able to deliver it. There is no question about that. I would love to see you try to say that Boigas aren’t actually delivering their venom or that Heterodon aren’t either.

> There may be some debate over a few species in which the delivery system is particularly rudimentary... protovenomous versus prevenomous but when looking at the potential biological specializations associated with commonly accepted rear fanged venomous colubrids- heterodon don't quite clear the bar.

You are making a completely artificial distinction to drag a red herring across the entire trail. Using your own definition of venomous, they meet your own criterion since they have specialized toxins produced in a specific gland and have a particular mechanism for getting the toxins past the skin.

Please try to persuade me that Rhabdophis or Dispholidus aren't venomous. They have the exact same system.

Ciao
B