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Journal of Experimental Biology, Vol 202, Issue 22 3127-3134, Copyright © 1999 by Company of Biologists

JOURNAL ARTICLES

Accommodation in the cuttlefish (Sepia officinalis)

F Schaeffel, CJ Murphy and HC Howland
Department of Experimental Ophthalmology, University Eye Hospital, Rontgenweg 11, D72076 Tubingen, Germany.

We have studied natural accommodation in the eye of six specimens of cuttlefish (Sepia officinalis) as they were fed with fish and shrimp. Using infrared photoretinoscopy, we observed (1) that the resting refractive state of the cuttlefish was emmetropic or slightly hyperopic, (2) that accommodation took place only a fraction of a second before a strike and (3) that accommodation focused selectively only in the frontal visual field while no change in refraction could be measured in the lateral field of view. Accommodation was bilateral and amounted to approximately 5 diopters (the reciprocal of the focal length expressed in meters). Simultaneously, the eyes converged. It appears that, as in most teleost fishes, accommodation in the cuttlefish involves a movement of the crystalline lens perpendicular to the axis of the eye. In histological sections, we observed the position and arrangement of the ciliary muscles, confirming earlier anatomical descriptions, and developed a model of how accommodation could be achieved.




© The Company of Biologists Ltd 1999