Meeting Abstract
In a majority of ray-finned fishes (Actinopterygii), affective acquisition of food resources is predicated on rapid jaw adduction after prey enters the oral cavity. Although it is understood that the dorsal adductor divisions that arise from the head and insert on the posterior of the lower jaw are major contributors to closing dynamics, the contribution of the ventral components of the adductor system has been completely overlooked. In many ray-finned fishes, the ventral component is comprised of a single division, the Aω, that originates on an intersegmental aponeurosis of the facialis divisions and inserts on the medial face of the dentary, anterior to the insertion of the dorsal divisions. Thus, this configuration resembles a two-anchor sling applied to a third-order lever with offset anc.hor points. The goal of this study was to elucidate the contributions of the Aω to jaw adduction by modeling jaw closing in the deep-sea viperfish Chauliodus sloani. To do this, we simulated adduction with a completely novel biorobotic system that incorporates the geometry of the Aω. By comparing results between simulations that included and excluded Aω input, we show that the Aω adds substantially to lower-jaw adduction dynamics in C. sloani by displacing the line of action of the dorsal facialis adductor muscles and increasing the mechanical advantage and input moment arms of the jaw lever system. Modifications of mechanics and posture result in significant increases in closing performance, including bite force, angular velocity, and adduction time. In the context of our results, the prevalence of a similar Aω sling design across the fish tree of life indicates the importance of this division in feeding and identifies a productive topic for future comparative work.
