Meeting Abstract
Fish possess several morphological features that characterize their feeding habits and strategies as unique. Gill rakers, located on the pharyngeal (medial) side of the gill arches, fall within this category. While their role in feeding behavior and diet has been well studied in individual teleost species, much remains to be learned about their exact function and histological structure, especially in a comparative context. Previous studies have observed that gill rakers are covered with asymmetrical arrangements of polygonal epithelial cells. The taste buds found at the peak of these cells demonstrate a morphological adaptation to protrude them, thereby increasing their efficiency in food selection. In addition to taste buds, gill rakers possess mucous cells that aid in the passage of food through the aggregation and lubrication of small food particles. The present study sought to characterize raker functional properties across trophic niches (herbivore, carnivore, omnivore) and feeding modes (filter-feeder, benthic), through the use of histological staining and morphological data in Cypriniformes. Dane’s mucosal stain reveals the presence of mucopolysaccharides, important mucous cell components. Morphological data was obtained through microdissection of 13 species, in which the entire branchial arch structure and individual ceratobranchial were removed. The total number, average spacing, length and width (tip, base) of each gill raker were measured. Benthic feeders present shorter, narrower-spaced rakers while omnivores and carnivores demonstrate longer, wider-spaced rakers. Such results indicate an association of gill raker structure with diet, wherein gill raker morphology may play a role in the size of the food particles that can be consumed.
