Meeting Abstract
Paddlefish (Polyodon spathula) are freshwater, filter-feeding fish with a highly developed electrosensory system that the fish use to interact with their environment. The functional units of electrosensation are ampullae of Lorenzini; these structures occur in large numbers on the head, operculum and rostrum of the paddlefish. In order to assess changes in numbers of ampullae as young fish grow, this study quantifies the number of ampullae specifically on the operculum of several size classes of juvenile paddlefish. Surface pores associated with the ampullae were imaged microscopically after Sudan Black B staining of isolated opercula, and pores were counted using an image analysis program. We predict that the number of ampullae on the operculum, which shows relatively isometric growth relative to the body, will show a lower rate of increase over early growth in comparison to the rostrum, which shows dramatically positive allometric growth. Rostrum ampullae data from a companion study will be used for comparison with opercular counts in similar size-groups of fish. Better understanding of the development of the paddlefish electrosensory system can contribute to greater appreciation for the early life history of this species, which could be significant in conservation efforts.
