“It’s always been a mystery why fangs have evolved so many times in snakes, but rarely in other reptiles. Our study answers this, showing how easy it is for normal snake teeth to turn into hypodermic needles,” said lead author Dr. Alessandro Palci.
Among the nearly 4,000 species of snakes that are living today, about 600 are considered “medically significant,” meaning that a bite would likely require treatment at the nearest hospital.
Snake fangs are modified teeth that are grooved and larger than other teeth, explained the researchers. These modifications can be located at the back or the front of the mouth.
“Snake fangs are an iconic exemplar of a complex adaptation, but despite striking developmental and morphological similarities, they probably evolved independently in several lineages of venomous snakes,” wrote the study authors.
“How snakes could, uniquely among vertebrates, repeatedly evolve their complex venom delivery apparatus is an intriguing question.”
For the investigation, the researchers used high-tech modeling, fossil evidence, and hours of microscope observations. They found that snakes possess tiny infoldings, or wrinkles, at the base of their teeth. Most likely, these infoldings help teeth attach more firmly to the jaw.
The study revealed that in venomous snakes, one of these folds gets deeper and extends all the way to the tip of the tooth – producing a venom groove and a fang.
“Our examination of venomous and non-venomous species reveals that most snakes have dentine infoldings at the bases of their teeth, known as plicidentine, and that in venomous species, one of these infoldings was repurposed to form a longitudinal groove for venom delivery,” explained the researchers.
According to study co-author Professor Michael Lee, the research highlights the opportunism and efficiency of evolution. “Wrinkles which helped attach teeth to the jaw were repurposed to help inject venom.”
The study is published in the journal Proceedings of the Royal Society B Biological Sciences.