Meeting Abstract
Goldfish, cypriniform generalists, are well-equipped for bottom-feeding given both a ventrally-directed mouth and palatal organ for sorting detritus. As bottom feeders goldfish likely represent the basal condition for this clade, however cypriniforms have radiated into a number of ecological niches. While a great many cypriniforms have remained benthic feeders, many have secondarily adopted filter and surface feeding. The ability to feed efficiently within a diverse number of ecological niches has allowed this group to thrive. Using XROMM we have examined the kinematics of suction feeding at the surface versus along the bottom. Although the prey types were not significantly different, goldfish showed significant differences in kinematic profiles when feeding from these two different positions. Neurocranial elevation, in particular showed patterns that were not clearly consistent with prey position. While attacks on the surface showed that gape and neurocranial elevation were synched, these movements were not synched during benthic feeding. The extent of gape was not consistently correlated to the degree of neurocranial elevation. Importantly strikes directed at the bottom were often preceded by a ventral rotation of the neurocranium, a movement not previously noted that would have been nearly impossible to characterize without the use of XROMM. Precise movements of the premaxilla depend on location of prey, suggesting that cypriniforms have substantial flexibility in positioning their mouths during premaxillary protrusion. We suggest that the complexity associated with increased numbers of linkages in the head adds to the potential flexibility in feeding kinematics. This would be particularly important in opening up feeding niches early during the radiation of this group.
