Mandibular Protractions and Their Correlation with Meal Size in Juvenile Thai Snakes During Ingestion of Rodent Prey

Abstract

Nine neonatal and juvenile snakes, four vipers and five nonvipers, were fed rodent meals varying in size, expressed as percent of snake body weight. The number of mandibular protractions and the time to complete swallowing were recorded, with both measures increasing linearly as a function of meal size. These young snakes routinely swallowed meals that were 50% of body weight, and ranged up to 80%, far higher than meals reported by previous workers studying adult vipers (36.4%) and nonvipers (18.4%). Furthermore, the slopes of regressions relating mandibular protractions to meal size in all of our snakes were lower than comparable slopes for adult vipers or nonvipers. We hypothesized that the relatively long and wide skulls of young snakes (i.e., as proportion of body length) were responsible for these ingestive accomplishments, with negative allometric growth being responsible for performance changes during ontogeny.