Johnathan Evenson, David Penning
Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon (D. corais, D. couperi, and D. melanurus), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results showed that bite force scaled isometrically with head dimensions but showed negative allometry relative to body length, reflecting ontogenetic body elongation rather than diminished cranial performance. When expressed as pressure, biting by Drymarchon generated tissue-level stresses exceeding those produced by constriction in comparably sized snakes. Dietary synthesis revealed extreme trophic breadth dominated by non-avian reptiles, particularly snakes, with no relationship between predator size and prey size. Together, these results resolve a biomechanical paradox by demonstrating that high bite pressure, prolonged jaw engagement, and behavioral persistence can support lethal prey subjugation in the absence of venom or constriction. These findings highlight simple seizing as an effective and underappreciated prey-handling strategy, and underscore the importance of integrating biomechanics, behavior, and natural history to understand the evolution of snake feeding systems.