[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2011]

Most people think that venomous snakes inject their poison into their prey through hollowed fangs. But this is not quite so true …

Scientists have recently discovered that there is more to the journey of venom from predator to prey than previously thought. Although the ‘hollowed fang’ theory is not completely a myth, it is only true for about one seventh of venomous snake species.

Anyone who has witnessed a snake biting its prey (or has had the unfortunate experience of being bitten themselves) will know how quick the action is. So how is venom able to enter the blood system in such a short time? And where does this venom come from?
Most snakes have solid fangs, used for piercing the skin of their chosen prey. The latest research has discovered that each of these fangs have a longitudinal grove down which the venom flows when needed. Venom either runs out from between the snake’s tissue and fangs or, as in most venomous species, the venom runs down the groves and into the bite wound.
But the real reason for this research is the evolutionary success relating to all this. Science has added more and more clarity to the many ‘mysteries’ of species development. Birds, for example, do not only have feathers for warmth and flight. In bird evolution, specifically for protection, feathers adapted to include the function of ridding unwanted parasites and exterior dangers.
To stick with the above example, one might then argue that venom would be brushed away by birds’ feathers, just as pests are, before it enters the wound.
But what is of particular interest is that snake venom turns from a viscous consistency to slightly more liquid as the fangs make contact with the skin. This allows for venom to instantaneously flow down the fang groves into the chosen prey. Without the attractant of the skin being pierced, the venom remains ‘sticky’ inside the snake until needed.
It is the speed of their reflexes that make snakes such successful predators. Not only the physical speed in reaching their prey for the attack, but also the physiological speed involving the transformation of viscous venom into a more liquid form able to flow down paired fangs and into their target.  
Source: Bruce Young, Florian Herzog, Paul Friedel, Sebastian Rammensee, Andreas Bausch, J. van Hemmen. Tears of Venom: Hydrodynamics of Reptilian Envenomation. Physical Review Letters, 2011; 106 (19) DOI: 10.1103/PhysRevLett.106.198103
Viewed online [http://www.sciencedaily.com­ /releases/2011/05/110516121728.htm]