SHEFFIELD, England — A visionary discovery made gazing into the eyes of fruit flies has overturned previous beliefs on what insects see.
Peering into their compound eyes with a custom built microscope and high speed camera, researchers found they were being looked back at in a level of detail higher than previously thought possible.
“By using electrophysiological, optical and behavioural assays with mathematical modelling we have demonstrated that fruit flies have much better vision than scientists have believed for the past 100 years,” says Mikko Juusola, Professor of Systems Neuroscience at the University of Sheffield and lead author of the study in a press release.
In the past, it was assumed that insects’ multi-faceted eyes could only see a sort of pixelated composite image of the world around them. Now, using their custom equipment, researchers are seeing that the insects have “twitching” photoreceptor cells that sample the world around them at an incredibly high rate. These movements, in addition to being microscopic, are also so fast that they can’t be seen with the naked eye.
To further enhance their vision, the insects also utilize a technique that all people do too, whether we realize it or not.
“From humans to insects, all animals with good vision, irrespective of their eye shape or design, see the world through fast saccadic eye movements and gaze fixations,” says Juusola.
What this means is that we have to constantly make tiny movements with our eyes to keep what we are seeing clear, otherwise we adapt to the visual input and clarity fades. A similar but slower effect happens when you are in a room with a certain smell — stay in the room long enough and you no longer perceive the scent.
“It has long been known that fast visual adaptation results in the world around us fading from perception unless we move our eyes to cancel this effect,” Juusola explains. “On the other hand, fast eye movements should blur vision which is why it has remained an enigma how photoreceptors work with eye movements to see the world clearly. Our results suggest that by adapting the way photoreceptor cells sample light information to saccadic eye movements and gaze fixations, evolution works towards optimizing the visual perception of animals.”
In other words, the coordination between the fly’s microscopic photoreceptor twitches and its visible movements is a dance choreographed over millions of years of evolution. The result: hyper-acute vision.
The researchers, including scientists from Beijing, Cambridge and Lisbon, suggested that the findings could find potential use in improving robotics.
The study comes following other new insights on insect sight this summer, including research that explores how dragonflies track and predict the path of their prey.
Juusola and his colleagues findings were published today in the journal eLife.