Meeting Abstract

70.1  Jan. 7  Cyprinodont premaxillary protrusion and prey capture: does mechanism dictate behavior? FERRY-GRAHAM, L.A.*; GIBB, A.C.; Calif. State Univ./Moss Landing Marine Labs; Northern Arizona Univ.

Premaxilla protrusion is thought to confer a number of feeding advantages in teleost fishes. Cyprinodontiformes (Atheriniformes, Acanthopterygii) exhibit protrusion where the descending process of the premaxilla does not rotate anteriorly to occlude the sides of the open mouth during prey capture. Previous kinematic study of Gambusia (Poecilidae: Cyprinodontiformes) revealed that the premaxilla retracts fully prior to jaw closure and thus does not serve to reduce the distance between the upper and lower jaws, as is seen in most fish with jaw protrusion. We hypothesized that this is a functional consequence of the immobile descending process and/or the manner in which momentum is transferred to the premaxilla. We examined multiple cyprinodont taxa to assess variation in the mobility of the descending process, identify potential mechanisms that transfer momentum to the premaxilla, and determine the functional consequences of variation (e.g., contribution of the premaxilla to jaw closing). Individuals (N ≥ 4) of each species were imaged at 250-500 fps during prey capture to quantify cephalic movements, and cleared and stained specimens were used for morphological analysis. Cyprinodont species differed in the contribution of the premaxilla to jaw closure, although there was no difference in the mobility of the descending process of the premaxilla or in the apparent mechanism of momentum transfer. Therefore, the underlying mechanism does not prevent the premaxilla from contributing to mouth closure. Further, it appears an individual can alter the contribution of the premaxilla to mouth closure on an event-specific basis. This may reflect a foraging ecology where prey items are sucked or picked from the substrate, water column, or surface. This flexibility is unusual, as most teleosts employ a stereotyped movement of the premaxilla for suction feeding.