Imagine you are a god and you have to design the poisonous fangs of a snake. Which form is the best and should you put it In the front of the jaw or in the back? Fact is that there are three types of venomous snake fangs: Boomslangs for example have fixed grooved fangs in the end of the jaw (type I). Just imagine a fang with a slit/groove in which the venom is floating. This grooved structure was the base for the evolution of tunnel fangs which improve the poison injection. Evolutionary, the ends of the groove came together and a closed, and tunnel-like structure was born. There are snakes like the cobra where you can still see the “two ends” rolled together. These are the closed but non-fused fangs, which are located in the front of the jaw (type II). Even more advanced are the fangs of vipers etc. There the rolled ends are smoothed. Their closed fused tunnel fangs can be also found in the front of the jaw and they are mobile (foldaway) (type III). Chris Broeckhoven and Anton du Plessis (Biology Letters, 2017) wondered if the evolutionary change in location (back to front) is a result of the change in structure (grooved to tunnel). Maybe the change in structure changed the stress amount under load and therefore a different location was favourable? So they analysed the structure, length and location of fangs in 20 different snake species and used computer models to predict the stress under load. Interestingly, the structure (grooved or tunnel) didn’t changed the highest stress value (always near the fang tip). The stress just correlated with the length: longer fangs could break easier. However, curve form and more stable material can compensate for that. So change in location has nothing to do with the stability of the fang. Instead they assume that it has something to do with the hunting strategy. Snakes with grooved fangs in the end of the jaw focus on the bite-and-hold strategy while the vipers with the mobile tunnel fangs in the front of the jaw focus on the bite-and-release strategy. SO… IF you are god and have to design the poisonous fangs of a snake ask for her preferred hunting strategy. "Has snake fang evolution lost its bite? New insights from a structural mechanics viewpoint"
Broeckhoven and du Plessis A (2017) Biology Letters 13(8): 20170293.
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