Beetles beat Avatar to circular polarization

Posted by Emma Woollacott

Jewel scarab beetles can see using circularly polarised light - the same as is used in 3D movies such as Avatar. And they don't even need special glasses.

According to researchers from the University of Texas, it's a big advantage for the jewel scarab species Chrysina gloriosa, because most of the light reflected off their colorful bodies happens to be circularly polarized.

"The trait would allow the beetles to easily see each other while simultaneously hiding from predators that cannot see circular polarized light," said physicist Parrish Brady.

Circular polarization (CP) is a way of filtering light that causes the light's electric field to travel in a circular pattern, as opposed to oscillating in all directions as it does in unpolarized light.

CP filters are now used to create 3D effects in movies - but we don't have the ability to perceive CP light, which is why we need special glasses.

The team took advantage of beetles' propensity to fly toward light and tested to see if jewel scarabs alter their flight patterns in the presence of CP light.

"We found significant differences in the beetles' flights toward circularly polarized and unpolarized light sources, suggesting that their eyes are outfitted to be sensitive to circularly polarized light," Brady said.

The finding makes Chrysina gloriosa only the second species on Earth known to be sensitive to CP light — the other being a species of shrimp.