Rapid replacement of fangs in the sit-and-wait viperid, Cerastes vipera

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Jaim Sivan, Life Sciences, Achva Academic College, Shikmim, Israel, Itay Tesler, Blaustein Institutes for Desert Research, Ben-Gurion University, Beer Sheva, Israel, Allan A. Degen and Michael Kam, Blaustein Institutes for Desert Research, Ben Gurion University, Beer Sheva, Israel

Background/Question/Methods
The Saharan Sand viper, Cerastes vipera, is one of the smallest viperid species, measuring up to 35 cm in length. This viper is nocturnally-active and is limited to sand and dune systems across northern Africa’s Saharan countries, the Sinai Peninsula and, in Israel, across the western Negev. This snake preys predominantly on lizards and captures its prey employing mainly sit-and-wait hunting. After striking, Cerastes vipera holds its prey for several minutes during which time the prey struggles to free itself;
Venomous viperid snakes possess relatively large and fragile hollow fangs that are employed as an integral part of a sophisticated and advanced envenomation apparatus for predation. We hypothesized that fangs serve much like disposable needles and predicted a high loss rate and, hence, high replacement rate of fangs in free-ranging snakes. The snakes also possess smaller rear teeth that aid in the swallowing of the prey. We reasoned that these teeth are less delicate than fangs and predicted that the loss of these teeth would be at a slower rate that the delicate fangs. To test our predictions, we analyzed fecal samples for fangs and rear teeth of free-ranging Cerastes vipera, in the Northern Negev desert, Israel.

Results/Conclusions
In total, 213 free-ranging C. vipera were examined for fecal or digestive matter. Of these, 90 samples were obtained of which 38 (42 %) were fecal samples from the ground (Table 1). One to 3 fangs were found in 11 adults and 3 neonates, and 2 to 25 regular teeth in 11 adults and 6 neonates. Nearly 25% of fecal samples contained fangs, averaging more than one fang per sample and, consequently, our first prediction was supported. Based on our findings that fangs are replaced each fourth predation, and that C. vipera captures prey every 5 days, we estimated that replacement rate under natural conditions is at the high rate of every twenty days. Furthermore, fecal samples contained rear teeth at the same proportion as fangs, indicating that the rapid replacement of teeth is not limited to fangs but also to rear teeth and, therefore, our second prediction was not supported. These findings reflect the importance of front fangs and rear teeth in hunting prey in free-ranging C. vipera. This is the first quantitative report of fang and rear teeth loss in a free-ranging viperid, and we believe that similarly high rates of loss occur in other viperid species.