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Brittle Star

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Leith
972071.  Tue Feb 12, 2013 6:10 pm Reply with quote

Ophiocoma wendtii

This species of brittle star has a unique* form of vision. Its upper surface is covered with tiny calcite crystals, 40 to 50 micrometres in diameter. These crystals focus light onto photoreceptor cells beneath them, making the Ophiocoma wendtii's whole body a sort of compound eye.

During the day, pigmented cells cover the calcite crystals, acting like sunglasses to protect the photo-receptors from bright light.

Researchers believe that this brittle star can detect light, shade and movement sufficiently well to help it find shelter and avoid predators.

Ophiocoma wendtii's crystal lenses are (or recently were) more sophisticated than any microlenses engineered by humans. They have inspired new approaches in the development of miniature lenses that may come to be used as components of optical computers.

* Unique in living animals, that is. Similar crystal eyes have also been found on trilobite fossils. Interesting article on trilobite vision here:
http://www.fossilmuseum.net/Evolution/TrilobiteArmsRace.htm

Sources:

University of Washington: How a Star Avoids the Limelight
Marinebiotech.org: Marine Biomimetics (see section "The Eyes Have It")

 

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