Hogg, C;
Neveu, M;
Folkow, L;
Stokkan, KA;
Hoh Kam, J;
Douglas, RH;
Jeffery, G;
(2015)
The eyes of the deep diving hooded seal (Cystophora cristata) enhance sensitivity to ultraviolet light.
Biol Open
, 4
(7)
pp. 812-818.
10.1242/bio.011304.
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Abstract
The mammalian visual range is approximately 400-700 nm, although recent evidence suggests varying ultraviolet (UV) extensions in diverse terrestrial species. UV sensitivity may have advantages in the dim, blue light shifted environment experienced by submerged marine mammals. It may also be advantageous when seals are on land as UV is reflected by snow and ice but absorbed by fur, enhancing visual contrast. Here we show that the pelagic hooded seal (Cystophora cristata) has a highly UV permissive cornea and lens. Seals like other carnivores have a tapetum lucidum (TL) reflecting light back through the retina increasing sensitivity. The TL in this seal is unusual being white and covering almost the entire retina unlike that in other carnivores. Spectral reflectance from its surface selectively increases the relative UV/blue components >10 times than other wavelengths. Retinal architecture is consistent with a high degree of convergence. Enhanced UV from a large TL surface with a high degree of retinal convergence will increase sensitivity at a cost to acuity. UV electrophysiological retina responses were only obtained to dim, rod mediated stimuli, with no evidence of cone input. As physiological measurements of threshold sensitivity are much higher than those for psychophysical detection, these seals are likely to be more UV sensitive than our results imply. Hence, UV reflections from the TL will afford increased sensitivity in dim oceanic environments.
| Type: | Article |
|---|---|
| Title: | The eyes of the deep diving hooded seal (Cystophora cristata) enhance sensitivity to ultraviolet light |
| Location: | England |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1242/bio.011304 |
| Publisher version: | http://dx.doi.org/10.1242/bio.011304 |
| Additional information: | © 2015. Published by The Company of Biologists Ltd This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. |
| Keywords: | Enhanced Contrast, Hooded Seal, Retina, Ultraviolet |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1472942 |
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