A comparative study of the anatomy of the iris and ciliary body in aquatic mammals
The ciliary muscle exhibits considerable variation in its development among the vertebrates. The muscle is considered to be well developed in humans, primates, ungulates, and aquatic carnivores, and the extent of development is thought to correspond to the amplitude of accommodation. The recent find...
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Canadian Science Publishing
1991
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crcansciencepubl:10.1139/z91-366 2024-09-09T19:33:20+00:00 A comparative study of the anatomy of the iris and ciliary body in aquatic mammals West, J. A. Sivak, J. G. Murphy, C. J. Kovacs, K. M. 1991 http://dx.doi.org/10.1139/z91-366 http://www.nrcresearchpress.com/doi/pdf/10.1139/z91-366 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Zoology volume 69, issue 10, page 2594-2607 ISSN 0008-4301 1480-3283 journal-article 1991 crcansciencepubl https://doi.org/10.1139/z91-366 2024-08-01T04:10:02Z The ciliary muscle exhibits considerable variation in its development among the vertebrates. The muscle is considered to be well developed in humans, primates, ungulates, and aquatic carnivores, and the extent of development is thought to correspond to the amplitude of accommodation. The recent finding of a well-developed ciliary muscle in the hooded seal (Cystophora cristata) has initiated interest in an accommodative mechanism for vision in air and in water. This study is a comparative investigation of the ciliary muscle in a number of aquatic mammals. The methods include gross inspection of the ciliary region and histological examination of the ciliary body and iris by means of light microscopy. The results indicate that in completely aquatic mammals the ciliary muscle is rudimentary, and in fact, appears to be lacking in one species (beluga whale). The ciliary muscle appears to be better developed in the amphibious pinnipeds (California sea lion, elephant seal, and walrus). The presence of circular muscle bundles suggests that the muscle is more developed in the elephant seal and California sea lion than in the walrus. The degree of ciliary muscle development and the need for accommodation can be related to the natural history of each species. Article in Journal/Newspaper Beluga Beluga whale Beluga* Cystophora cristata Elephant Seal hooded seal walrus* Canadian Science Publishing Canadian Journal of Zoology 69 10 2594 2607 |
institution |
Open Polar |
collection |
Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
The ciliary muscle exhibits considerable variation in its development among the vertebrates. The muscle is considered to be well developed in humans, primates, ungulates, and aquatic carnivores, and the extent of development is thought to correspond to the amplitude of accommodation. The recent finding of a well-developed ciliary muscle in the hooded seal (Cystophora cristata) has initiated interest in an accommodative mechanism for vision in air and in water. This study is a comparative investigation of the ciliary muscle in a number of aquatic mammals. The methods include gross inspection of the ciliary region and histological examination of the ciliary body and iris by means of light microscopy. The results indicate that in completely aquatic mammals the ciliary muscle is rudimentary, and in fact, appears to be lacking in one species (beluga whale). The ciliary muscle appears to be better developed in the amphibious pinnipeds (California sea lion, elephant seal, and walrus). The presence of circular muscle bundles suggests that the muscle is more developed in the elephant seal and California sea lion than in the walrus. The degree of ciliary muscle development and the need for accommodation can be related to the natural history of each species. |
format |
Article in Journal/Newspaper |
author |
West, J. A. Sivak, J. G. Murphy, C. J. Kovacs, K. M. |
spellingShingle |
West, J. A. Sivak, J. G. Murphy, C. J. Kovacs, K. M. A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
author_facet |
West, J. A. Sivak, J. G. Murphy, C. J. Kovacs, K. M. |
author_sort |
West, J. A. |
title |
A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
title_short |
A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
title_full |
A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
title_fullStr |
A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
title_full_unstemmed |
A comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
title_sort |
comparative study of the anatomy of the iris and ciliary body in aquatic mammals |
publisher |
Canadian Science Publishing |
publishDate |
1991 |
url |
http://dx.doi.org/10.1139/z91-366 http://www.nrcresearchpress.com/doi/pdf/10.1139/z91-366 |
genre |
Beluga Beluga whale Beluga* Cystophora cristata Elephant Seal hooded seal walrus* |
genre_facet |
Beluga Beluga whale Beluga* Cystophora cristata Elephant Seal hooded seal walrus* |
op_source |
Canadian Journal of Zoology volume 69, issue 10, page 2594-2607 ISSN 0008-4301 1480-3283 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/z91-366 |
container_title |
Canadian Journal of Zoology |
container_volume |
69 |
container_issue |
10 |
container_start_page |
2594 |
op_container_end_page |
2607 |
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1809902716333326336 |