Distribution of Ganglion Cells and Object Localizing Ability in the Retina of Three Cetaceans

Abstract

The distribution of ganglion cells was examined in the retina of three cetacean species: the false killer whale, the pacific white-sided dolphin and the beluga. Three parameters of vision were estimated from the distribution of ganglion cells, i. e., the retinal resolving power (visual acuity), the field of best vision, and the direction of visual axis. In these three species, the retinal resolving power was 2.6-3.3 cycles per degree, the width of field of best vision was 12.8-15.4°, and the direction of visual axis was 51-68° from the geometric center of the retinal hemisphere. Interspecific differences are small, and these parameters are similar among most marine cetaceans. However, there are many differences in these parameters between marine cetaceans and terrestrial mammals.