Shrimp communicate using ‘secret’ light code

By Madeleine van der Linden 20 November 2015
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Queensland scientists have discovered a new form of secret light communication in mantis shrimp.

QUEENSLAND SCIENTISTS HAVE uncovered that mantis shrimp use light with special properties to deceive prey and communicate in secret – findings that could one day lead to a faster method for detecting cancer cells.

Mantis shrimp (Gonodactylaceus falcatus) are one of the only animals with the ability to see a certain type of light called circularly polarised (CP) light – that is, light waves that oscillate in a cork screw-like motion. The shrimp have special body patterns on their head, legs and armoured tail that can only be seen with CP light.

While scientists have known for some time that mantis shrimp have this extremely rare ability, they weren’t sure what they used it for until now.

A perfect code

In the study, researchers at the Queensland Brain Institute at the University of Queensland placed mantis shrimp in a tank of water with two burrows for the shrimp to use – one reflecting CP light, the other unpolarised light.

The researchers found the mantis shrimp almost always avoided the burrow reflecting CP light, leading them to believe the shrimp use the light as a way of covertly advertising their presence and warning other shrimp to stay away. Their findings are published in the journal Current Biology.

 “Shrimp use smell to detect each other, but the problem with smell is that everyone else can smell it too. No one else can see the circularly polarised light, so it’s a perfect code,” said Dr Yakir Gagnon, who led the study along with Professor Justin Marshall. 

“What we’re discovering is there’s a completely new language of communication,” said Justin.

Cancer cell detection

Understanding how mantis shrimp use CP light could have important implications for cancer detection, because cancerous cells reflect polarised light very differently to healthy cells. For example, a camera equipped with circular polarisation sensors might one day detect cancer cells long before the human eye can see them.

“In the future we should be able to use light sensors to examine the health of tissue without having to cut out parts to sample,” said Yakir. However, he added there are still “layers and layers of discovery” before connecting the mantis shrimp research with any human applications.