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Morphology of the Normal eye of the California Sea Lion (Zalophus californianus) with Attention to Accommodation Dick Dubielzig Carmen Colitz Judy St Leger.

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Presentation on theme: "Morphology of the Normal eye of the California Sea Lion (Zalophus californianus) with Attention to Accommodation Dick Dubielzig Carmen Colitz Judy St Leger."— Presentation transcript:

1 Morphology of the Normal eye of the California Sea Lion (Zalophus californianus) with Attention to Accommodation Dick Dubielzig Carmen Colitz Judy St Leger

2 Pinniped Vision Evolutionary offshoot of the carivora –Holangiotic retina –Canine-like tapetum Adaptations for underwater vision –Relatively round lens Adaptations for vision out of water –Small pupillary aperture –Relatively flat corneal curvature Accommodation Adaptations for vision in dim light at great depths –Tapetum covers an extensive portion of the fundus –Mechanisms for pupil dilation

3 Size of the Eye California Sea Lion 4.94cm x 3.64 cm Elephant Seal 6.2cm x 4.46 cm

4 Adaptations for underwater vision - The round lens

5 Adaptations for vision out of water Flattened corneal surface Pinpoint pupil

6 Pinniped vision and Accommodation Review of the literature Schusterman et.al, Why Pinnipeds don’t echolocate J Accust Soc Am 2000 –No echolocation Hanke et.al., Corneal topography, refractive state, and accomodation in Harbor Seals (Phaco vitulina) Vision Research 2006 –Flattened corneal plateau –Myopia and astigmatism in air and emmotropia and no astigmatism in water West et.al. (Murphy), A comparative study of the anatomy of the iris and ciliary body in aquatic mammals. Can J Zool 1991 –Documents the arrangement and orientation of the iris and ciliary muscles in pinnipeds

7 Morphologic Features

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11 Contact Between the Ciliary Pars Plicata and the Lens Capsule

12 Regulation of Pupil Size Pupil size increases in water in dim light but not on land (Schusterman) Since the dilator muscle is rudimentary, might this represent a forward movement of the lens in water?


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