The position of the retinal area centralis changes with age in Champsocephalus gunnari (Channichthyidae), a predatory fish from coastal Antarctic waters |
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Authors: | T Miyazaki T Iwami V B Meyer-Rochow |
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Institution: | (1) Graduate School of Bioresources, Mie University, Tsu Mie, 514-8507, Japan;(2) Tokyo Kasei-Gakuin University, Machida Tokyo, 194-0292, Japan;(3) Faculty of Engineering and Sciences, Jacobs University, P.O. Box 750561, 28725 Bremen, Germany |
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Abstract: | Histological examinations of the topographical distribution and the area of highest density (the area centralis: AC) of presumed retinal ganglion cells found in the retina in 0- to 6-year-old Champsocephalus gunnari revealed differences between younger and older fish. Individuals of up to 2 years of age had the AC in the temporal retina,
whereas in 3-, 4-, 5- and 6-year-old fish it was positioned in the ventro-temporal region of the retina. The main visual axis
in the pitch plane of C. gunnari was shown to shift from facing forward to an upward-forward direction during growth, corresponding to the habitat change
in this species from pelagic to benthic. Moreover, the AC in 0- to 3-year-old fish was near the retinal periphery, but displaced
towards the inner retina in 4- to 6-year-old fish. This means that the visual axis in the horizontal plane of the younger
fish was directed towards the frontal sector of vision, while in the older fish a slightly more lateral position was favoured.
Therefore, younger fish can be expected to possess superior binocular vision when it comes to prey closely in front of them,
but in older fish it seems more important to have a wider visual field to detect prey (and possibly predators) within a greater
volume of water. |
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