This Disappears When Logged In

Venomous Colubrid Theory

Discussion in 'General Venomous' started by Herptile, Oct 3, 2009.

  1. Herptile

    Herptile Active Member

    A few months ago, I heard about this really elite herpetologist known as Bryan Fry. He has this theory that all colubrids are venomous, from garter snakes on up. What do you guys think?
     
  2. murrindindi

    murrindindi Elite Member

    Bryan Greig Fry knows what he`s talking about, he discovered that snakes, varanids and iguanians are all closely related and many of the previously "harmless" snakes and lizards do have venom systems.
     
  3. Herptile

    Herptile Active Member

    Re: Venomous Colubrid Theroy

    I don't doubt Fry's herpetological ability or his status as a herpetologist at all. It just that it is kinda a radical theory. I mean garter snakes may have some bacteria in their saliva or something. All I'm saying is that he should make a list of suspected venomous species and target those. Cat scane them and see if they have any form of venom apparatus. Active or not.
     
  4. Merlin

    Merlin Administrator Staff Member Premium Member

    What he is looking at is the presence of certain proteins in the saliva. Colubrids etc to not have any sort of venom delivery system.
     
  5. murrindindi

    murrindindi Elite Member

    Boiga dendrophila (Golden-ringed cat snake/ Mangrove snake) is a rear fanged colubrid, although the venom is not considered potent to humans... I think David McConley will be able to expand on that!
     
  6. Merlin

    Merlin Administrator Staff Member Premium Member

    I probably should have said North American colubrids since that was what the question was basically about.
    There is little doubt that rear fanged snakes have some sort of venom.
    However innocuous. ;)
     
  7. murrindindi

    murrindindi Elite Member

    I forgive you! ;)
     
  8. Dragoness

    Dragoness Elite Member

    They are finding out lots of animals that are harmless have venom, usually weak venom, or we would have noticed it long before now. Even bearded dragons have venom that is very similar to rattlesnake venom, just very very diluted!
     
  9. KrokadilyanGuy3

    KrokadilyanGuy3 Elite Member

    I think he just wants everything to be venomous.
     
  10. Snakelings

    Snakelings Well-Known Member

    Someone must have told that garter snake that tried to gum me to death that he was venomous... He sure tried to kill me. Luckily he didn't have any teeth and just managed to leave my hand covered in saliva. :)

    It's an interesting theory though. I'd like to see some official paperwork on the studies.
     
  11. Venomdoc

    Venomdoc Member

    Chewing through the various threads on this site. To access the papers, go to the scientific publication section section of my website www.venomdoc.com

    One in particular that is relevant to this thread is this one
    http://www.venomdoc.com/venomdoc/Scientific_publications_files/2008_BGF_Evolution_of_an_Arsenal.pdf

    We looked at a vast range of the advanced snakes. All aspects from the shape of the venom gland (using histology and MRI), to the dentition to the chemical composition of the venom glands.

    Garter snakes have in fact produced symptomatic (but far from life-threatening) envenomations. The key is that being venomous is not the same as being medically important from a human perspective. Thus most of these snakes should not be considered as 'venomous' in the legal framework in regards to the laws banning venomous private keeping. Just as all spiders are venomous but only a handful are medically important to humans.

    Cheers
    Bryan
     
  12. Dragoness

    Dragoness Elite Member

    Also, Colubrid kind of ended up as a blanket designation for snakes that didn't fit precisely anywhere else. Their classification is not always clear or fitting.
     
  13. Cid

    Cid Elite Member


    look into western hognoses, i cant site the sources that i have heard this from, but i have heard and read that the Western Hognose (a rear fanged coloubrid) does have a mild venom. but its practically harmless and will only result in a rash or so if you are actually bitten...
     
  14. Dragoness

    Dragoness Elite Member

    Opisthoglyphous (rear-fanged) colubrid snakes are what account for the vast majority of truly venomous colubrids, and includes the relatively harmless Hognose and Mangrove snakes, as well as the deadly Boomslang, and thelotornis snakes, among others.

    Rear fanged snakes actually have a primitive venom delivery system, and grooved teeth that channel the venom into the puncture created by said tooth. They have venom glands.

    Many colubrids simply rely on the chemicals in their saliva - and not fangs or specialized teeth of any type. I have yet to hear if there are glands of any special type producing said chemicals....

    Hognose do posses mild venom, (and fangs and glands) and everything I have heard about them says you really have to try to get bit, much less bit well enough to achieve envenomation, and on those cases, symptoms were mild, typically including mild local numbness. They are pretty good at feinting, or lunging as if to bite, but not actually biting.

    Personally, I think if we are only looking at what's in the saliva (Remembering Venom is a unique compound, produced in a gland, and expressed through (in the case of snakes) specialized dentition) then just having slightly toxic or irritating saliva does not qualify for the title. If it does, then even humans could probably be listed as a venomous species.
     
  15. Venomdoc

    Venomdoc Member

    Dragoness it might be helpful if you read the article I referred to above:
    http://www.venomdoc.com/venomdoc/Scientific_publications_files/2008_BGF_Evolution_of_an_Arsenal.pdf

    You will see that such venom glands is a basal characteristic of the advanced snakes and, further, a number of toxins are shared across the advanced snakes, e.g. three finger toxins (the hallmark of cobra venoms) have been sequenced and tested by us from a wide range of 'colubrid' snakes. They are not delivering 'saliva' but rather proper venom. However, this does not mean all are of medical importance.

    Dentition is also quite variable, ranging from basic teeth through very enlarged, grooved teeth, with such variations on a theme also scattered widely across the tree. The documented lethal species are not necessary even the ones with the most spectacular dentition. "Opisthoglyphous" is an out-dated term that has no biological reality as significant enlargement of the teeth has occurred on multiple occasions in the different lineages. Thus such snakes to not form a natural group.

    Once you are done reading that paper, I would be glad to answer any questions you may have.

    Cheers
    Bryan
     
  16. murrindindi

    murrindindi Elite Member

    Its just fascinating, I don`t see how anyone who`s read the papers can have any doubt, the evidence is quite clear; colubrids ARE venomous to some extent, at least!
     
  17. Merlin

    Merlin Administrator Staff Member Premium Member

    The term "venomous" has been synonomous with "dangerous" for so long that people do not think about "harmless" snakes as being potentially "venomous".

    People are slow to change the way that they think about things.
     
  18. murrindindi

    murrindindi Elite Member

    That`s very true, if an animal is venomous (especially a snake), it could be a possible danger to ourselves, which doesn`t help their long-term survival; "The only good snake is a dead one" type of mentality is still alive and well, as far as many people are concerned.
    I think Bryan will be kept VERY busy far into the future, but I know he wouldn`t want it any other way!
     
  19. Dragoness

    Dragoness Elite Member

    My computer does not have an easy time with Adobe. Opening an adobe document will freeze it up (this machine is over a decade old). I'll probably check out the article at work, or print it from there, depending on length. Thank you for posting it.

    What (if any) would be the classifying difference between an animal that is Venomous, and one that merely has toxins present in their saliva? I was under the (mistaken?) impression that venom came with a specialized delivery system - in snakes, it would typically be fangs and attached venom glands - mostly because of the method venom must be delivered to be effective. Last I knew (and maybe this too has changed - this stuff gets updated faster than I can keep up with it), Venom was venom because it pretty much had to be injected into the bloodstream to be effective.

    If there is newer information, I am interested - much of what I was taught at work is outdated. Many of my coworkers still subscribe to the idea that Varanids are not venomous, and instead, still perpetuate the idea that they simply have nasty bacteria in their saliva. Last I knew, that had been disproven as well.
     
  20. Venomdoc

    Venomdoc Member

    Venom is defined as as a secretion, produced in a specialised gland in one animal and delivered to a target animal through the infliction of a wound (regardless how tiny it could be), which contains molecules that disrupt normal physiological or biochemical processes so as to facilitate feeding or defence by the producing animal. Ordinary teeth are sufficient to puncture the skin and then venom is chewed in. Specialised hollow teeth are further refinements, not an essential aspect. These teeth are useful for puncturing thick scales or going through long fur. For predating on a frog, such armament is not necessary.

    As for the komodo dragon, that is also my work.
    http://www.venomdoc.com/downloads/2009_Fry_Komodo&Megalania
    http://www.venomdoc.com/downloads/2006_BGF_Nature_squamate_venom_press.pdf

    and here is a paper that ties it all together
    http://www.venomdoc.com/downloads/2009_Fry_Toxicofera_review.pdf

    Cheers
    Bryan
     

Share This Page