This release is also available in German Scientists at the Max Planck Institute for Brain Research in Frankfurt, at the University of Duisburg-Essen, and at the Charles University in Prague have now discovered that in contrast to previous assumptions, the eyes of subterranean African mole-rats have a rather well-structured retina with an unusually high proportion of cone photoreceptors. Cones are the photoreceptors for daylight vision, hence their usefulness in the lightless world of mole-rats is puzzling. As a further peculiarity, most mole-rat cones contain a blue-sensitive visual pigment, whereas in other mammals most cones have a green-sensitive pigment. The density of rods, the photoreceptors for low-light night vision, is much lower in the mole-rats than in nocturnal surface-dwelling rodents. These findings, published in the European Journal of Neuroscience in March 2004, call for a revision of our current views on the visual system of subterranean mammals.

A remarkable number of mammals have turned to a completely or partially subterranean mode of life during the course of evolution - almost 300 species of rodents, insectivores and marsupials. As a presumed evolutionary adaptation to their lightless habitat, most of these subterranean species have reduced small eyes and are considered blind. As far as current knowledge goes, the African mole-rats (blesmols, Bathyergidae) are strictly subterranean rodents. They live, breed and forage underground, feeding on roots, bulbs and tubers. The eyes are small (diameters of 1.5 - 2.5 mm) depending upon the species. Leo Peichl at the Max Planck Institute for Brain Research in Frankfurt/Main, Pavel Nemec at the Charles University Prague and Hynek Burda at the University Duisburg-Essen have now had a closer look at the eyes of three species, Ansell's mole-rat Cryptomys anselli, the giant mole-rat C. mechowi, and the naked mole-rat Heteroc
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Contact: Prof. Dr. Leo Peichl
peichl@mpih-frankfurt.mpg.de
49-699-676-9348
Max-Planck-Gesellschaft
5-Apr-2004

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