Meeting Abstract

81.2  Friday, Jan. 6  A Device for Dampening Drag: A Novel Hypothesis for the Function of Enormous Fangs in Deep-sea Fishes KENALEY, Christopher/P; Harvard University

Many deep-sea fishes possess spectacular morphologies that enable the capture of large prey in a seascape devoid of biomass. Perhaps the most distinctive feeding morphologies of deep-sea teleosts are enormous fangs set on extremely long jaws. Although the functional significance of these phenotypes has long been assumed (e.g., caging or impaling devices), no single study has addressed what functional advantages enormous fangs confer. In recent years, a handful of studies have employed theoretical models to predict feeding performance and to describe the dynamic forces associated with jaw adduction in deep-sea fishes. These studies have demonstrated that the most important force opposing jaw adduction in long-jawed, deep-sea taxa, namely drag, differs substantially from that of shallow-water taxa, namely inertia of the lower-jaw system. As a corollary, any prey item put in motion by the jaws of a deep-sea predator might impose much greater negative forces associated with drag and that this might alter adduction performance considerably. Based on these insights and a series of feeding simulations for several species of the dragonfish family Stomiidae, a new hypothesis is proposed for the function of enormous fangs of deep-sea fishes. A theoretical model that accounts for mass and the hydrodynamic properties of typical dragonfish prey items predicts that fangs function to optimally position prey in such a manner that reduces negative forces acting on the lower jaw. These results demonstrate that without optimal positioning by long teeth, the capacity of dragonfishes to consume large prey items is severely diminished.