Last updated February 9, 2018 at 10:10 am
The praying mantis has unique 3D vision abilities – we know that because scientists stuck 3D glasses on them.
Praying mantises are the only insects with stereoscopic vision, which means they can perceive depth and three-dimensional structure. Humans also have this type of vision, and ours works by comparing the tiny differences in the images we receive in our right and left eyes.
Mantises, though, compare the differences in movement between their eyes. This means they only see in 3D when the scene or object moves – making their stereoscopic vision precise, robust, and perfectly suited for catching prey.
To discover this, researchers used a basic form of 3D movies. For a human, this would involve wearing glasses with a red filter on one eye and blue on the other. For a praying mantis, it involves having tiny lenses temporarily glued to your face with beeswax.
When the team set up their insect 3D cinema, they started by showing the bugs video of prey. When the mantises attempted to catch the movie meal, the researchers knew the 3D illusion was effective.
They then moved on to showing the mantises the same sort of complex dotted patterns that are used to research stereoscopic vision in humans. This meant that for the first time, bug and human vision could be directly compared.
The researchers found that mantises only look for places where the picture changes – not just ignoring anything that doesn’t move but not even seeing it in three dimensions.
“This is a completely new form of 3D vision as it is based on change over time instead of static images,” says behavioural ecologist Dr Vivek Nityananda. “In mantises it is probably designed to answer the question ‘is there prey at the right distance for me to catch?'”
This knowledge could be applied to future robotic and computer vision systems, says researcher Dr Ghaith Tarawneh.
“Many robots use stereo vision to help them navigate, but this is usually based on complex human stereo. Since insect brains are so tiny, their form of stereo vision can’t require much computer processing. This means it could find useful applications in low-power autonomous robots.”
This research was published in Current Biology.