Natures wonders:robber fly top gun of flying insects (Introduction)

by David Turell @, Sunday, March 12, 2017, 18:59 (1072 days ago) @ David Turell

Fabulous long range vision from its complex compound eye and high speed in flight allows it to hone in at a fast closing angle to get its prey:

"A small fly the size of a grain of rice could be the Top Gun of the fly world, with a remarkable ability to detect and intercept its prey mid-air, changing direction mid-flight if necessary before sweeping round for the kill.


"The robber fly has incredibly sophisticated eyes: like all flies, it has compound eyes made up of many lenses -- in the case of the robber fly, it is thought to have several thousand lenses per eye. However, unlike many species of fly, it has a range of lens sizes, from just over 20 microns to around 78 microns -- the width of a human hair. The larger lenses are the same size as those of a dragonfly, which is believed to have the best vision of all insects but is 10 times larger, and help reduce diffraction which would otherwise distort the image.


" the robber fly has a concentration of larger lenses in the centre of its vision, accounting for only around one thousandth of its visual space. The lenses get smaller in size around the outside of the eye. Importantly, the team of researchers also showed that below the very large central lenses, this robber fly has evolved extremely small light detectors, which are placed almost parallel to each other and much further away from the lens than normal. This arrangement preserves the high local image resolution, which is very close to that of much larger dragonflies.

"When it sees a potential prey, the fly launches itself upwards while maintaining a 'constant bearing angle' -- in other words, it moves in a direction such that while moving closer and closer to its prey, it still maintains the same relative bearing. This ensures that it will intercept its prey.


"This strategy of maintaining the constant relative bearing also allows the robber fly to manoeuvre itself mid-air in the event that its prey changes direction. The researchers demonstrated this by switching the direction of their fake prey while the robber fly was mid-flight and observing how the fly responded.

"Once the fly is around 29 cm away from its prey -- though exactly how it judges this distance is still unclear -- the fly displays a remarkable strategy never before observed in a flying animal. It 'locks-on' to its prey while changing its own trajectory, enabling it to sweep round, slow down and come alongside the prey to make its final attack.

"'What you see is similar to a baton pass in a relay race: when the two runners are heading in a similar direction and speed, they are more likely to be successful than if they are passing each other at ninety degrees," says Dr Trevor Wardill.

"The researchers believe the robber fly's sensory system, which maximises precision in its vision while minimising the amount of information needing processing, is the key to its ability to capture prey as accurately is it does while retaining such a small body size."

Comment: Amazing how that tiny brain computes the calculus of baring in on a snack. I would put this in the category of another saltation. I can't imagine the insect learning tis stepwise. It would have stayed very hungry.

I might add another comment: How did that very complex compound eye develop? Not stepwise either. It requires a designer.

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