The combination of fangs and venom has made snakes fearsome predators.
The widespread presence of fangs in snakes raises questions about evolutionary processes. Snakes have evolved fangs multiple times, including significant variations in their positioning in the jaw, both anterior and posterior.
A recent study has explained why snakes are particularly suited to develop effective venom delivery systems, while other venomous species have not.
Snakes have evolved fangs multiple times.
Researchers examined the teeth of various snake species, both living and extinct, in search of a feature known as plicidentine.
In the Proceedings of the Royal Society B, scientists reported the presence of plicidentine in every snake species they studied, except for Anilios (Ramphotyphlops) bicolor, a species of burrowing blind snake, suggesting this is a key factor.
The lead author, Dr. Alessandro Palci from Flinders University (Australia), stated that plicidentine consists of ridges near the base of the teeth. They appear to provide a foundation for the venom delivery system, a natural selection mechanism that improves when beneficial for snakes whenever they use venom to subdue prey or fend off enemies.
In some venomous snake species, these plicidentine folds extend into grooves along the length of the fangs, through which venom flows. They may even close over the grooves to create hollow fangs that function like hypodermic needles.
Venom is produced near the back teeth, making it easier for the posterior fangs to develop, while the anterior fangs prevent snakes from needing to grip tightly onto prey to achieve a good bite.
In recent years, many lizard species have also been found to possess venom production capabilities, with some species having potential medical applications. However, these venoms are relatively weak compared to most snake species. Very few lizards have mouths structured to deliver venom effectively, significantly reducing the threat they pose.
Dr. Palci noted that lizards must rely on “packaging” their venom in their saliva. This may explain why they have never developed truly potent venom.
The most apparent question that arises from this is why plicidentine developed in the first place. The authors concluded that it helps anchor teeth to the jawbone.
Snakes and monitor lizards share similar jaw structures. The increased anchoring area provided by plicidentine may be an evolutionary solution to this potential weakness. It is purely coincidental that this feature has another function. It seems that the development of plicidentine dates back close to the origins of cobras, as it has been observed in Yurlunggur, a giant extinct Australian snake genus from 20 million years ago.
Although blind snakes may have lost this characteristic, Palci stated: “It may also be due to their teeth being very small. In pythons, we can only see plicidentine in their larger teeth.”
