Quantitative analysis of the effect of prey properties on feeding kinematics in two species of lizards

Studies of the functional morphology of feeding have typically not included an analysis of the potential for the kinematics of the gape cycle to vary based on the material properties of the prey item being consumed. Variation in prey properties is expected not only to reveal variation in feeding function, but allows testing of the functional role of the phases of the gape cycle. The jaw kinematics of two species of lizards are analyzed when feeding trials are conducted using quantitative control of prey mass, hardness and mobility. For both species, there were statistically significant prey effects on feeding kinematics for all the prey properties evaluated (i.e. prey mass, hardness and mobility). Of these three prey properties, prey mass had a more significant effect on feeding kinematics than prey hardness or mobility. Revealing the impact of varying prey properties on feeding kinematics helps to establish the baseline level of functional variability in the feeding system. Additionally, these data confirm the previously hypothesized functional role of the slow open (SO) phase of the gape cycle as allowing for physical conformation of the tongue to the surface of the food bolus in preparation for further intraoral transport.