Meeting Abstract
Shortly after hatching, larval/early-juvenile stage paddlefish go through a profound series of morphological, behavioral and physiological changes – including changes in pigmentation, growth of a rostrum, and shifts in feeding. Another major transformation occurring during this dynamic period is the growth of large numbers of long, fine gill rakers; these structures are critical for the filter-feeding lifestyle of juvenile and adult paddlefish. Using histology and image analysis, this report details the development and growth of gill rakers in larval and juvenile paddlefish. Numbers of rakers, their lengths and inter-raker spacing are quantified for young fish of various sizes. Cell and tissue features associated with the growing gill rakers are also characterized. Understanding gill raker development and characteristics can lead to a more integrated understanding of the dramatic changes occurring during the critical larval-juvenile period in this species. For example, the ram ventilation filter-feeding of larger paddlefish requires anatomical accommodation (optimized gill rakers) as well as behavioral correlates. We also report comparative results of gill raker analysis for related Acipenseriformes – Atlantic sturgeon (Acipenser oxyrinchus) and lake sturgeon (Acipenser fulvescens). Comparison of these species allows consideration of the relationships between gill raker structure and diet and feeding behavior in this order of basal ray-finned fishes. Greater understanding of feeding mechanisms and behaviors throughout development in paddlefish may have application in conservation efforts.
