Enlarged teeth is discussed very well in Dennis Desmond's web site, http://www.hognose.com/pages/venomous.htm#venomous



I would like to add some information to his article. I recently attained an excellent publication (Witwer, M.T. 1995. Heterodon and other not-so-harmless "harmless" snakes. Journal of the Northern Ohio Association of Herpetologists. 16 (1):12-20. ), that addresses much of what you're asking.



Tooth morphology in this genus is described, the rear teeth are latterly flattened and are ungrooved. All that it says about how the venom is delivered is that the tubules lead into a duct which opens in the vicinity of the posterior maxillary teeth. So it is probably more like what you said, it just mixes with the saliva and seeps in. What are the main purposes of the enlarged teeth? During swallowing, the enlarged rear teeth contact the prey item first. It is obvious to see that the teeth are meant for holding the prey item, especially since they do not constrict, nor is their venom really strong enough to subdue their prey within a short period of time. They must rely on their teeth to hold the prey in place until they tire. The author also claims that since they have longer teeth instead of having a greater number of equally teeth, this means there is a greater bite force concentrated at the point of contact, thereby increasing the penetrating capabilities. This may be especially beneficial if the prey is inherently difficult to grep such as the frogs and toads they are famous for!



As far as toad popping, the jaws of Heterodon are strong enough to deflate toads without the benefit of enlarged teeth. It has been nearly 30 years since there was research done on the length of the enlarged teeth that determined they are not long enough to puncture a toad's lungs, unless the toads were swallowed belly up. This is a classic case of a myth being perpetuated incessantly through the Internet and without any real research being done on the topic.



I hope this helps!
click here for the link


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