Insect mandibles are “multi-purpose” tools: they are used for cutting, masticating, digging, material transport, prey capture and defense. In contrast to this functional complexity, the kinematic space of most insect mandibles is thought to be fully characterised by a simple hinge joint. Although widespread, this assumption is based solely on morphological inference; quantitative kinematic analysis are lacking.
We developed a recording setup and kinematic analysis framework to rigorously test the “hinge joint hypothesis” in leaf-cutter ants. At large opening angles, mandibles yaw, consistent with a simple hinge joint. But at small opening angles, mandibles can both yaw and pitch, suggesting multiple degrees of freedom, and that insect mandibles may be capable of more complex motion than traditionally assumed.
Read: Three-dimensional kinematics of leaf-cutter ant mandibles: not all dicondylic joints are simple hinges
