Meeting Abstract

3.6  Tuesday, Jan. 4  Feeding kinematics of a juvenile cyprinid predator, Ptychocheilus lucius, are characterized by negative allometry BURNETTE, M.F.*; GIBB, A.C.; Northern Arizona University; Northern Arizona University burnmf0@wfu.edu

During ontogeny, allometric changes (i.e. changes in organism shape) may alter behaviors critical to individual fitness, such as feeding. Understanding the changes that occur as animals grow and how animals respond to these changes is one overarching goal of studies of ecophysiology. We investigated changes in cranial morphology and kinematics during feeding in an endangered cyprinid piscivore, the Colorado pikeminnow (Ptychocheilus lucius). The juveniles examined here encompass a size range over which pikeminnow undergo a shift in diet from insects to fish, which could be associated with a change in feeding behavior. Alternately, under the assumption of isometric growth, we hypothesized that both cranial morphology and linear kinematic variables measured during feeding would scale in direct proportion to body length, while angular kinematic variables would remain unchanged. We found that cranial morphology demonstrates several different patterns of allometry, while most kinematic variables scale with negative allometry. Kinematic displacements were proportionally larger in small pikeminnow. Smaller pikeminnow produced faster attacks, in which they reached maximum displacement of the cranial elements faster than larger pikeminnow. We hypothesize that, as juvenile pikeminnow grow larger, individuals will generate proportionally less buccal pressure, relative to the size of the predator and the prey item it is attempting to capture. This, in turn, suggests that juveniles undergo a transition from suction-based to ram-based prey capture. Further investigation of suction-based models of prey capture for small and large juvenile pikeminnow may elucidate the relationship between changing head morphology and feeding kinematics for Colorado pikeminnow.