Meeting Abstract
Most fish feeding studies focus on prey capture, especially during suction feeding. The other half of a feeding event – getting prey from the mouth to the gut – is just as essential for successful feeding. But this occurs inside the mouth, hidden from view, making it difficult to study how fishes handle prey intra-orally. In order to track intra-oral transport and swallowing, we used X-ray Reconstruction of Moving Morphology (XROMM) to study feeding in channel catfish (Ictalurus punctatus, n = 3). We marked the prey and seven bones on the left side of the head, recording a total of 25 feeding events. By reconstructing the 3D trajectories of the prey beads in the oral and buccal cavities, we were able to track how the fish move prey through the mouth, and the point at which the prey passes through the esophagus. Prey moves through the oral cavity at high velocities as a continuation of the suction event, but comes to a full stop once it reaches the pharyngeal basket, where it then moves in a slower, more complex path before being passed to the esophagus. This slow phase coincides with little motion in the head and no substantial mouth opening or hyoid depression, suggesting that pharyngeal raking, rather than hydrodynamic manipulation, is responsible for prey transport in the buccal cavity. By contrast, once the prey is past the esophagus, its motion is tightly correlated with a “gulping” motion (hyoid depression, pectoral girdle retraction, and mouth opening) in the head. Our results indicate that catfish use phases of pharyngeal and hydrodynamic manipulation to direct prey into the esophagus, but how these gulping motions are moving prey in the esophagus is unclear.
