Aquatic Mammals (1986)


(…) Dolphins are well-known for their developed hearing and echolocation systems. However, data on the organization of other sensory systems in these animals are limited. Namely, the organization of the visual system of dolphins and other cetaceans adapted for visual perception both in the water and air is still unclear.

To understand the mechanisms of visual perception it is important to obtain the information on the structural organization of the best vision zone of the retina with high density of ganglion cells, similar to the area centralis in the retina of some vertebrates. Such data were obtained by DRAL (1975, 1977,1983) for two species of dolphins-Tursiops truncatus and Delphinus delphis. The dolphin’s retina was shown to have two areas with increased density of ganglion cells. This fact is of utmost importance, indicating specific organization of vision in the dolphins.

The present paper is concerned with a topographic study on the density of ganglion cells in the retina of another species of dolphins – the porpoise Phocoena phocoena L. The aim of our study was to perform measurements enabling accurate mapping of ganglion cell distribution in the retina. (…)