Correlation between Feeding Behaviors and Retinal Photoreceptor Cells of Largemouth Bass, Micropterus salmoides, in Korea

The largemouth bass (Micropterus salmoides), a food resource in Korea, is a highly voracious predator, designated as an invasive species. It is both diurnal and nocturnal, with high adaptability and reproducibility. Since the predation characteristics are associated with sensitive dynamic visual acuity, we examined the ocular structure of the largemouth bass to investigate the association between photoreceptor cells and feeding behavior. Furthermore, the comparison of the prey-tracking ability of M. salmoides with that of other predatory fish (Coreoperca herzi and Lepomis macrochirus) with similar ecological characteristics revealed the structure and arrangement of photoreceptor cells, typical of a predatory fish in M. salmoides. The double and single cone cells in the retina were present in the regular mosaic patterns of the quadrilateral units, with four double cone cells surrounding a single cone cell. The photoreceptor cells, i.e., the rod, single, and double cone cells of M. salmoides, were smaller (2.3 ± 0.2, 3.82 ± 0.2, and 7.5 ± 0.2 µm, respectively) than those of other species (3.1 ± 0.24, 6.6 ± 0.5, and 11.3 ± 0.4 µm in diameter, respectively, in C. herzi). A smaller diameter of cone cells allows for a high-density arrangement of visual cells, possibly affecting the dynamic visual acuity for prey tracking.