Calcitic microlenses as part of the photoreceptor system in brittlestars

@article{Aizenberg2001CalciticMA,
  title={Calcitic microlenses as part of the photoreceptor system in brittlestars},
  author={Joanna Aizenberg and A. D. Tkachenko and Steve Weiner and Lia Addadi and Gordon Hendler},
  journal={Nature},
  year={2001},
  volume={412},
  pages={819-822}
}
Photosensitivity in most echinoderms has been attributed to ‘diffuse’ dermal receptors. Here we report that certain single calcite crystals used by brittlestars for skeletal construction are also a component of specialized photosensory organs, conceivably with the function of a compound eye. The analysis of arm ossicles in Ophiocoma showed that in light-sensitive species, the periphery of the labyrinthic calcitic skeleton extends into a regular array of spherical microstructures that have a… 
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