Structure de la rétine et potentialités visuelles susceptibles d'influer sur le comportement trophique du loup (Dicentrarchus labrax) adulte et en cours de développement
Mani-Ponset, L.; Diaz, J.P.; Divanach-Kentouri, M.; Connes, R. (1993). Structure de la rétine et potentialités visuelles susceptibles d'influer sur le comportement trophique du loup (Dicentrarchus labrax) adulte et en cours de développement, in: Barnabé, G. et al. (Ed.) Production, environment and quality: Proceedings of the International Conference Bordeaux Aquaculture '92, Bordeaux, France, March 25-27, 1992. EAS Special Publication, 18: pp. 359-372
In: Barnabé, G.; Kestemont, P. (Ed.) (1993). Production, environment and quality: Proceedings of the International Conference Bordeaux Aquaculture '92, Bordeaux, France, March 25-27, 1992. Special Publication European Aquaculture Society, 18. European Aquaculture Society: Gent. 587 pp., more
In: Special Publication European Aquaculture Society. European Aquaculture Society: Bredene. ISSN 0774-0689, more
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| Authors | | Top |
- Mani-Ponset, L.
- Diaz, J.P.
- Divanach-Kentouri, M.
- Connes, R.
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| Abstract |
The retina in adult sea bass displays all the characteristics of arhythmic fishes. The retinal motor responses of the well-developed pigmentary epithelium ensure adaptation to brightness variations. The presence of a lipid tapetum lucidum, abundant rods and large cones improve vision under weakly lit conditions. In addition, the square mosaic layout of single and twin cones may contribute to the perception of movements and form a major advantage in hunting fast prey. Study of retinal organogenesis indicates that photo-sensitivity may appear 3d after hatching when the first photoreceptors differentiate. The larvae then possess positive phototropism but avoid strong light, as is shown by their vertical distribution in rearing tanks. Their sight improves from day 5, when their trophic life begins and when the retinal structure becomes similar to that of adults, although it is simpler. Prey discrimination is thus possible at from 1mm in specimens 7 to 10d-old to 3mm on about day 13 and then increases to 5 or 6mm on about day 20. Until then, sea bass larvae only possess single cones which strictly limit vision to day sight and make night feeding impossible. After day 20, the progressive growth of twin cones and the forming of the square mosaic of photoreceptors enhances assessment of movement of both congeners and prey, making hunting more efficient and contributing to the first formation of groups. |
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