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Accommodation in the cuttlefish (Sepia officinalis).
F Schaeffel1, C J Murphy, H C Howland
1Department of Experimental Ophthalmology, University Eye Hospital, Röntgenweg 11, D72076 Tübingen, Germany.
The Journal of Experimental Biology
|December 14, 1999
Summary
Cuttlefish accommodation focuses vision in front just before striking prey. This study reveals how their eyes adjust focus using lens movement for hunting.
Area of Science:
- Marine biology
- Ophthalmology
- Animal vision
Background:
- Understanding visual systems in cephalopods is crucial for marine biology.
- Cuttlefish (Sepia officinalis) possess complex eyes, but their accommodation mechanisms remain incompletely understood.
Purpose of the Study:
- To investigate the natural accommodation response in cuttlefish eyes during feeding.
- To determine the timing, magnitude, and visual field specificity of accommodation in Sepia officinalis.
Main Methods:
- Infrared photoretinoscopy was used to measure refractive states in six cuttlefish specimens.
- Histological analysis of ciliary muscles was performed to understand anatomical structures.
- A model of the accommodation mechanism was developed based on observations.
Main Results:
- Cuttlefish exhibited emmetropic or slightly hyperopic resting refractive states.
- Accommodation occurred rapidly, fractions of a second before prey strike, and was bilateral.
- Focus adjustment (approx. 5 diopters) was selective to the frontal visual field; no lateral changes were observed.
- Eye convergence occurred simultaneously with accommodation.
Conclusions:
- Cuttlefish accommodation involves crystalline lens movement perpendicular to the visual axis, similar to teleost fishes.
- The findings provide insights into the functional morphology and visual ecology of cuttlefish predation.