Structure and optics of the eyes of the box jellyfish Chiropsella bronzie
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Cubomedusae have a total of 24 eyes of four morphologically different types. Two of these eye types are camera-type eyes (upper and lower lens-eye), while the other two eye types are simpler pigment pit eyes (pit and slit eye). Here, we give a description of the visual system of the box jellyfish species Chiropsella bronzie and the optics of the lens eyes in this species. One aim of this study is to distinguish between general cubozoan features and species-specific features in the layout and optics of the eyes. We find that both types of lens eyes are more severely under-focused in C. bronzie than those in the previously investigated species Tripedalia cystophora. In the lower lens-eye of C. bronzie, blur circles subtend 20 and 52° for closed and open pupil, respectively, effectively removing all but the coarsest structures of the image. Histology reveals that the retina of the lower lens-eye, in addition to pigmented photoreceptors, also contains long pigment-cells, with both dark and white pigment, where the dark pigment migrates on light/dark adaptation. Unlike the upper lens-eye lens of T.cystophora, the same eye in C.bronzie did not display any significant optical power.
KeywordsBox jellyfish Visual systems Photoreceptors Eyes Visual optics
The authors would like to thank Jamie Seymour, Matthew Gordon and Teresa Carrette at James Cook University, Cairns for their help and support in the field and for fruitful discussions. A. G. would like to acknowledge grant # 2005-1-74 from the Carlsberg Foundation and D.-E.N. would like acknowledge grants from the Swedish Research Council and the Swedish Foundation for Strategic Research (BioX). All of the experiments conducted in this study comply with the ‘Principles of animal care’, publication no. 86-23, revised 1985 of the National Institute of Health and with the current laws for animal care in Australia and Sweden.
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