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Marine animals use new form of secret light communication

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This image shows a mantis shrimp in a defensive position, on its back with its legs, head and heavily armored tail closed over. The red color indicates areas of reflected circular polarizing light. Credit: Credit Yakir Gagnon/QBI

Marine animals use new form of secret light communication

Posted: 19 Nov 2015 08:35 AM PST

A new form of secret light communication used by marine animals has been discovered by scientists. The findings may have applications in satellite remote sensing, biomedical imaging, cancer detection, and computer data storage. The new study shows the shrimp use circular polarisation as a means to covertly advertise their presence to aggressive competitors. “In birds, colour is what we’re familiar with; in the ocean, reef fish display with colour. This is a form of communication we understand. What we’re now discovering is there’s a completely new language of communication,” said Professor Marshall. Linear polarised light is seen only in one plane, whereas circular polarised light travels in a spiral — clockwise or anti-clockwise — direction. The team determined that mantis shrimp display circular polarised patterns on the body, particularly on the legs, head and heavily armoured tail; these are the regions most visible when when they curl up during conflict….Another study involving Professor Marshall, published in the same edition of Current Biology, showed that linear polarised light is used as a form of communication by fiddler crabs. Fiddler crabs (Uca stenodactylus) live on mudflats, a very reflective environment, and they behave differently depending on the amount of polarisation reflected by objects, the researchers found. “It appears that fiddler crabs have evolved inbuilt sunglasses, in the same way as we use polarising sunglasses to reduce glare,” Professor Marshall said. The crabs were able to detect and identify ground-base objects base on how much polarised light was reflected. They either moved forward in a mating stance, or retreated back into their holes, at varying speeds. “These animals are dealing in a currency of polarisation that is completely invisible to humans,” Professor Marshall said. “It’s all part of this new story on the language of polarisation.

 

  1. Yakir Luc Gagnon, Rachel Marie Templin, Martin John How, N. Justin Marshall. Circularly Polarized Light as a Communication Signal in Mantis Shrimps. Current Biology, 2015; DOI: 10.1016/j.cub.2015.10.047
  2. Martin J. How, John H. Christy, Shelby E. Temple, Jan M. Hemmi, N. Justin Marshall, Nicholas W. Roberts. Target Detection Is Enhanced by Polarization Vision in a Fiddler Crab. Current Biology, 2015; DOI: 10.1016/j.cub.2015.09.073

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