• 2021 (Vol.35)

Eye optics and retinal topography in the Eurasian beaver Castor fiber L.

© 2017 A. M. Mass, A. Ya. Supin

Institute of Ecology and Evolution RAS 119071 Moscow, Leninsky prospect, 33

Received 15 Feb 2017

Eye optics, retinal topography, and sizes of retinal ganglion cells were investigated in the Eurasian beaver Castor ber L. Eye optics provides emmetropy in air with the image scale of 8.9 mm/rad and hypermetropy underwater with the image scale of 4.75 mm/rad. Distribution of retinal ganglion cells in retinal wholemounts features a visual streak with increase cell density. In the visual streak, cell the maximum cell density was from 1200 to 2240 cells/mm2 for di erent wholemounts, mean 1700 cells/mm2. This density of ganglion cells results in the retinal resolution of 0.15o (9’, 3.3 cycle/deg). This value can be assumed the visual acuity in air. Underwater, the visual acuity is markedly less due to the lesser image scale and defocusing. Ganglion cell sizes varied from 7 to 29 μm, mean 14.9 μm in the high-density area and 14.3 μm in the low-density area. The visual system of the beaver is adapted to the aerial vision and is not ambivalent.

Key words: beaver, vision, retina, visual acuity

Cite: Mass A. M., Supin A. Ya. Opticheskaya sistema glaza i retinalnaya topografiya evraziiskogo bobra castor fiber l. [Eye optics and retinal topography in the eurasian beaver castor fiber l.]. Sensornye sistemy [Sensory systems]. 2017. V. 31(3). P. 191-201 (in Russian).


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