The Shrimp! They See Me Polarizations!

A new entry in the best title ever competition: arXiv:0804.2162, "The secret world of shrimps: polarisation vision at its best", by Sonja Kleinlogel and Andrew G. White. Secret lives of shrimp? That sounds more like an expose on the secret drug habits of the Roloffs on the T.V. show Little People Big World, than the title for a scientific article. (Yes it is politically incorrect to call little people "shrimps." Having spent the first many years of my life being stared at for have a little person as a sister, however, I think you can cut me some slack, and just laugh :) ) Let's see if makes it by the title police.

The paper shows, by the way, that the shrimp Gonodactylus smithiare actually measures circular polarizations of light. This is apparently the first biological system to be known to measure circular polarizations. Even more fascinating, apparently the shrimp perform a full characterization of the Stokes parameters of light, and thus are able to take full advantage of polarized light in its environment. What exactly, the shrimp are doing with this information, however, is, of course, the real question. All I know is that if I were a member of a cannibalistic species, I'd probably want any advantage I could find over my fellow shrimp. But how, exactly would seeing Jeffery Dahmer's polarization help me escape his evil deads?

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Hi

An article in New Scientist today describes cuttlefish as being able to alter the polarisation of light reflected off them, using it to send "secret" messages to other cuttlefish. Have the shrimp cracked the cuttlefish code? - it sounds like a research project to me.

It's actually an interesting article. I have a student that is very interested in vision and I had him read it. It's a fascinating idea, title notwithstanding.

This was first shown in a Current Biology paper last month - I've blogged about it here. Alan - the mantis shrimps can see in the types of polarised light that the cuttlefish use and given that cephalopods often eat mantis shrimps, the use of circular polarisation allows them to communicate in ways that even cuttlefish can't see.

As a slight semantic point, mantis shrimps aren't true shrimps.

>This was first shown in a Current Biology paper last month

Hmm, not quite!

Ed, Dr Sonja Kleinlogel was an author on both articles, I'm her co-author on the arXiv paper. The article in Current Biology showed that only the males in a different species of mantis shrimp could see circular polarisation vision, and so considered it was being used for shrimp secret sexual signalling. I think of this as the "prawnographic" hypothesis. :)

It can't be the whole story in our case though. We found the same structures in the eyes of both male and female mantis shrimps, and yet neither have circularly polarised markings on their bodies. Each eye measures the six polarisation components that are precisely required for optimal polarisation vision. In fact, the physics we used to understand what was going on is the same physics that we use in quantum computing for optimal storage of information.

To quote Sonja: "It is this unique talent to measure linear and circular polarisation simultaneously which presents a completely new concept of polarisation vision. There wouldn't be much point in only being able to see circular polarisation as it is extremely rare in nature. Even the polarized light reflected from some shrimp's bodies is only weakly circular polarised and often contains more linear polarisation than circular."