Metamorphosis and fish vision
Version of Record online: 11 OCT 2004
Copyright © 1990 John Wiley & Sons, Inc.
Journal of Neurobiology
Volume 21, Issue 7, pages 1037–1052, October 1990
How to Cite
Evans, B. I. and Fernald, R. D. (1990), Metamorphosis and fish vision. J. Neurobiol., 21: 1037–1052. doi: 10.1002/neu.480210709
- Issue online: 11 OCT 2004
- Version of Record online: 11 OCT 2004
- Manuscript Accepted: 20 JUN 1990
- Manuscript Received: 13 JUN 1990
Many species of fish exhibit metamorphosis in which dramatic external transformations occur as a consequence of coordinated changes in gene expression within an organism. Because postembryonic development and change appears to be the rule rather than the exception in teleost fish species, we view metamorphosis as one of many developmental strategies in fish which have continued plasticity as a common theme. Metamorphic changes are manifested in the visual system by modification of photoreceptor peak sensitivity rod photoreceptor cell addition, and retinal reorganization. These changes correspond to significant changes in the natural habitat of the animal and in its visual capabilities as demonstrated behaviorally. Thyroxine is the main metamorphic hormone as has also been found in amphibia. The sequence of metamorphic events occur in all teleosts, but they are compressed in time in direct developing animals suggesting that such animals might prove useful for understanding the evolution of metamorphosis in fish. It seems likely that rod photoreceptors may have evolved in conjunction with the change from larval to juvenile stage through metamorphosis in indirect developing fishes. During evolution, the contraction and/or loss of the larval stage has resulted in earlier appearance of rod photoreceptors during development although they always arise later than cone photoreceptors. This ontogenetic developmental sequence supports Walls's (1942) proposal that cones are phylogenetically older than rods and suggests that rods may have evolved several times.