Bite-Force Scaling Across Size Classes in the Alligator Snapping Turtle (Macrochelys temminckii) and the Common Snapping Turtle (Chelydra serpentina)

Seth M. LaGrange^1,*, Ethan J. Kessler¹, Zhuang Li², Flavio Morrissiey³, and Mark Merchant⁴

¹Illinois Natural History Survey, Prairie Research Institute, 1816 S. Oak Street, Champaign, IL 61820. ²Department of Engineering, McNeese State University, Lake Charles, LA 70605. ³Morrissiey Consulting, Orlando, FL 32837. ⁴Department of Chemistry, McNeese State University, Lake Charles, LA 70605. *Corresponding author.

Southeastern Naturalist,Volume 22, Special Issue 12 (2023): 440–456

Abstract
Understanding feeding performance can inform feeding ecology and niche dynamics. Macrochelys temminckii (Alligator Snapping Turtle) and Chelydra serpentina (Common Snapping Turtle) are closely related, sympatric species with documented interactions. To understand ontogenetic and interspecific differences in bite performance, we measured bite force in an ontogenetic series of 62 Alligator Snapping Turtles and 33 Common Snapping Turtles. Within species, bite force positively correlated with size but scaled differently by species. Alligator Snapping Turtles produced higher maximum bite forces overall throughout ontogeny than Common Snapping Turtles, although Alligator Snapping Turtles reach significantly larger maximum sizes than Common Snapping Turtles, thereby enabling them to produce higher maximum bite forces. Differences in bite force between these species provide biomechanical context for distinctions in the ecologies of both speciess.

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