Meeting Abstract
Aquatic organisms have evolved a spectacular array of mechanisms for generating suction, accelerating the jaws at high speed, and applying force for prey capture. The diversity of jaw closing muscles in fishes and their subdivision into multiple actuators for powering feeding may play a significant role in key evolutionary changes in feeding mechanics. Here, we analyze the evolutionary functional morphology of the feeding apparatus of 27 triggerfish species and use these data to explore the anatomical basis of balistid biomechanical diversity. A computational model of triggerfish jaws was developed and used to explore the biomechanical consequences of the unique triggerfish “clamshell bucket” jaw mechanism and identify the functional role of each muscle in the subdivided jaw adductor complex. Biomechanical variables of jaw performance were combined with analyses of trophic ecology and morphological observations, and then optimized onto a phylogenetic tree to identify patterns of structural and functional change in triggerfish feeding biology through evolution. This work shows that the evolution of a novel sliding jaw linkage and multiple jaw adductor muscle subdivisions in the triggerfish lineage have directly influenced several key aspects of bite performance. We also find that each of the six adductor mandibulae muscles are optimized for different functions and therefore differentially contribute to bite force and jaw rotation. In this way, triggerfishes are biomechanically capable of producing high bite force as well as high jaw closing velocity, and have a method of coping with the functional trade-off of force versus velocity. This work was supported by NSF IGERT grant DGE-0903637, a 2011 NSF EAPSI grant to C. McCord, and NSF grant DEB 1112763 to M. Westneat.
