Insects have much better vision and can see in far greater detail than previously thought, a new study has found.
Thousands of receptors that make up insects’ net-like ‘compound eyes’ rapidly move in and out of focus as they sample the world around them.
This rapid ‘twitching’ is so fast it cannot be seen with the naked eye, and helps to provide the insects with ‘hyperaccurate vision’, the researchers said.
Insects have much better vision and can see in far greater detail than previously thought. Scientists recorded the movement of photoreceptors inside fruit fly eyes using a bespoke microscope with a high-speed camera system (pictured is one of the tethered flies)
The new study, led by experts at the University of Sheffield, changes our understanding of insect and human vision, and could be used in industry to improve robotic sensors.
Scientists have long believed insects would not see fine images because their ‘compound’ eyes consist of thousands of tiny lens-capped ‘eye-units’.
Together, these should capture a low-resolution pixelated image of the surrounding world.
The human eye, in contrast, has a single lens, which slims and bulges as it focuses objects of interests on a retinal light-sensor known as a photoreceptor array.
By actively changing the lens shape in a process known as ‘accommodation’, an object can be kept in sharp focus, whether close or far away.
As the lens in the human eye is quite large and the photoreceptor array underneath it is densely-packed, the eye captures high-resolution images.
But the new study has found that insect compound eyes can also generate surprisingly high-resolution images.
This, the researchers say, has much to do with how the photoreceptor cells inside the compound eyes react to motion.
Unlike in the human eye, the thousands of tiny lenses which make the compound eye’s characteristic net-like surface, do not move, or cannot accommodate.
But the Sheffield researchers found that instead, photoreceptor cells underneath the lenses move rapidly and automatically in and out of focus.
Thousands of receptors that make up insects’ net-like ‘compound eyes’ rapidly move in and out of focus as they sample the world around them. This rapid ‘twitching’ is so fast it cannot be seen with the naked eye, and helps to provide the insects with ‘hyperaccurate vision’ (stock)
To record these movements inside fruit fly eyes stimulated with light, the researchers had to build a bespoke microscope with a high-speed camera system.
As they view the world through rapid eye bursts, the insects combine the snapshots with normal head/eye movements.
The resulting photoreceptor cell twitching allows insects, such as flies, to resolve the world in much finer detail than was predicted by their compound eye structure, giving them hyperaccurate vision.
Professor Mikko Juusola, lead author of the study, said: ‘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.
‘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.
‘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 show that by adapting the way photoreceptor cells sample light information to saccadic eye movements and gaze fixations, evolution has optimised the visual perception of animals.’