From: Ronald C. Blue (ron_at_u2ai.us)
Date: Sat Mar 22 2008 - 08:03:54 PDT
> Love Code: A twist of light only mantis shrimp can see
> Davide Castelvecchi
> For love, some would twist the laws of physics. Short of doing that,
> shrimp communicate with the other sex by spinning light waves, biologists
> find. The feat seems to be unique to this animal.
> Light is made of electromagnetic waves. These are electric and magnetic
> fields that wiggle perpendicular to each other and to a light ray's
> direction. Many invertebrates have sophisticated eyes that can detect
> wavelengths of light invisible to humans. Some, including bees, can also
> distinguish linearly polarized light. That's when a light ray's electric
> field wiggles not in varying directions, but rather in one precise
> direction that forms a right angle to the ray.
> Researchers now show that mantis shrimpwhich actually look more like
> lobsterscan tell when light is circularly, rather than linearly,
> polarized. That means that the electric field twists like a corkscrew as
> the light ray moves. The corkscrew can twist right or leftor, in
> biological terms, be right- or left-handed.
> Roy Caldwell of the University of California, Berkeley, suspected that one
> species of mantis shrimp, Odontodactylus cultrifer, might be able to
> distinguish circular polarizations. Animals in this species, especially
> adult males, are rare. But 2 years ago, thanks to a tip from a crustacean
> enthusiast, Caldwell obtained a 4 inch-long adult male originally from
> ©2008 Society for Science & the Public.
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