A giant shrimp living on Australia's Great Barrier Reef can see a world beyond the rainbow that is invisible to other animals, scientists said on Wednesday.

They view the world in up to 12 primary colors -- four times as many as humans -- and can measure six different kinds of light polarization, Swiss and Australian researchers reported.

polarization is the direction of oscillation in light waves.

Some of the animals they like to eat are transparent and quite hard to see in sea-water, except they're packed full of polarizing sugars. I suspect they light up like Christmas trees as far as these shrimp are concerned," said Andrew White of the University of Queensland.

And the shrimps probably use tiny changes in color and polarization to send sexual signals between males and females, the researchers believe.