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"buzz." Hold your breath, aim at the target, and swing your arms hard to hit it. You don't need to open your hand to know that you have failed. Because the "buzzing" sounded again, and across its happy and flexible figure in the air, as if laughing at your clumsy movements.

Unconvinced, you get up and chase the fly and run a few laps in the room, and when you finally live up to your efforts to pat it, you will gain a great sense of satisfaction! (of course, if you can't catch it, you may need to calm your manic heart. )

Photo Source: Pixabay, however, sometimes life is so magical, when you are panting and smug, you find this little thing flying trembling again, flying! Clearly hit it, why can it still fly? I can't help but wonder, did you get it or not?

Superpower 1: looking at the world in slow motion, the brains of flies are about 1 million times smaller than yours, and they are not smart. After all, these insects jump into deadly mosquito lamps one after another. But whenever we try to capture or attack this small creature in the flesh, we always seem to be fooled by it. In fact, no matter how fast you think you are, it is slow motion in the eyes of flies.

Like most insects, flies have a pair of compound eyes. Each of its eyes is made up of a large cluster of tiny, independent lens units (small eyes). Each eye can catch light independently and see the sky at different angles. In essence, these small eyes constitute a single pixel of fruit fly vision. Compared with millions of pixels in humans, the world resolution seen by flies is very low. But the ability to capture motion does not depend on the resolution.

All animals, including humans, essentially capture information about their surroundings like watching movies. There is no doubt that the world is continuous, but our visual system takes a single image at a specific frequency (critical flicker frequency), which is transmitted from the eyes to the brain and pieced together. Only pictures above this frequency are continuous in our view.

The flicker frequency changes from low to high, and the light spot seems to change from flicker to continuous.

Humans can see up to about 60 flashes per second, while the compound eyes of some flies can see about 250 times-four times faster than humans. If you take a fly to the cinema, a smooth movie picture looks like a still image to the fly, like a slide show. Compared with you and me, flies essentially see the world in slow motion, so they react as fast as superpowers to us.

Superpower 2: I have special takeoff skills but a strong ability to capture the speed of movement, which does not help flies escape from human claws, and more importantly, they can instantly take off from a stationary position when they find danger. For all flying animals (even aircraft), the whole flight start-up process is the core stage. They need to produce significant lift in a short period of time, and at the same time, the process must be stable and able to resist a certain degree of disturbance. The take-off strategies of different insects may be slightly different. Some flies mainly provide initial lift through leg extension and jump take-off, while others, such as mosquitoes and hovering flies, mainly rely on flapping their wings to provide lift.

The valved flies of Diptera (Calyptratae) have a pair of hind wings, which do not provide any upward lift for flies, and have degenerated (or evolved) into a mechanical receptor called a halteres. The balance rod acts like a gyroscope. It senses the rotation of the body and helps insects maintain their balance. When petaloid flies are still, they always flap their hind wings regularly, but the effects of this behavior have not been solved. But scientists can observe that valved flies take off much faster than other flies.

In 2021, scientists removed the balancing rods of some valved flies and found that their legs stretched more slowly, causing them to take off more slowly and more unstable. Scientists speculate that the swing of flies' hind wings can increase their sensory information, which can be transmitted directly to the legs without going through any central nervous system. This allows flies to take off as quickly as a conditioned reflex. In addition, the activation of the balance rod is likely to help the fly "warm up" before the start of the flight, allowing it to make a rapid transition from standing still to jumping off.

Superpower 3: "immune" damage and resistance to disturbance, but alert as flies, or can not avoid being hit by us. That's right! Sometimes we can actually get it. It's just that the enemy has another trick: "immune" damage. To be more precise, it is partially "immune". Rule out the situation of actually patting flies that are still on a certain plane. When we shoot flies in mid-air, the air always gives better treatment to these creatures of minimal mass-they can sense changes in the airflow and react quickly to escape; or simply be pushed away by the air between the hand and it (which is why the fly swatter needs a lot of holes). On the other hand, small creatures always have higher physical strength, so the force of our arms can hardly cause fatal damage to it.

Photo Source: Unsplash theoretically, when we attack some flying creatures, wings are always the most vulnerable. So even if we can't slap the fly directly, we can always destroy its fragile wings and make it fall to the ground. Why can it still fly? This has to admire the ability of life to resist disturbance.

Seemingly weak insects have a strong resistance to natural damage to the body. In many arthropods, the survival processes of molting, disease, predation and mate selection may cause physical damage at any time. According to a 2007 survey of natural arthropod populations, nearly 40% of some arthropod populations lack at least one complete appendage. This proportion is inconceivable to us, but it also proves that in the state of nature, disturbance may be a normal state, not a small probability event.

For flying insects, however, a slight damage to the wings can have a devastating effect. Because asymmetrical bodies are bound to lead to asymmetric aerodynamics, which quickly destroys the stability of their bodies when they fly. Unlike birds and bats, which are also good at flying, insects cannot repair wing damage on their own. So they have to make use of the coupling of nervous system and mechanical system to compensate for the disturbance caused by this kind of damage.

Photo: Pixabay flies are also highly resistant to wing damage. When the damage is within a certain range, they can be stabilized by mechanical regulation driven by sensory feedback, which sacrifices some flight performance (such as speed), but does not change the control of the internal nervous system [1]. Or they may adaptively change internal controls over time to ensure adequate flight performance. The latter is similar to the process in which the aircraft consumes fuel and reduces its mass during flight, so it is necessary to change the autopilot control parameters to ensure flight stability. The two mechanisms are not mutually exclusive, but scientists want to sort out how flies coordinate the relationship between the two, leading to a better understanding of the mechanism of flapping wings, such as insects or birds.

In a study published last November in the journal Science Advances, scientists built a cylindrical virtual reality flight site and placed two magnets at the top and bottom of the center. The researchers glued a stainless steel needle to the chest of the fruit fly (D. melanogaster) and tied it with a steel rope between two magnets so that the fly could only rotate around the axis in the middle plane. A circle of screens around the site can provide visual stimuli for fruit flies to test their optic nerve response.

Image source: in order to study the effects of wing injury, the researchers used miniature scissors to cut off part of the left wing of fruit flies along the radial direction as the experimental group, while fruit flies with intact wings served as the control group. Using 100fps's high-speed camera to capture the movement of fruit flies, the researchers were able to collect the flapping amplitude and frequency of each wing and the adjustment of the position of the abdomen. The results show that unilateral wing damage will increase the flapping frequency of Drosophila wings, which will lead to an increase in air resistance. Thus it can be seen that the fruit fly will actively increase the air resistance and reduce the flight speed, but can ensure the stability of the flight. At the same time, the researchers also observed that in order to make up for the torque asymmetry caused by wing damage, fruit flies will actively shift to adjust their abdominal position, and this process will also affect the visual response of fruit flies. This study fully demonstrates the adaptability of flies to wing damage, which may be of great significance to improve the fault tolerance of insect robots.

Abdominal deviation caused by wing damage. Photo source: the original paper, maybe the next time you are infuriated by a fly but can't get it, think about this article and you won't be discouraged. After all, it took hundreds of millions of years of natural selection to make flies what they are today.

Speaking of, a colleague in our editorial department is planning to keep a poisonous spider in the bedroom (to help him hunt mosquitoes), while others worry: "aren't you afraid of spiders biting you?" He replied, "so I can save the world!" When I rushed to the manuscript, I couldn't help thinking of this man's second year of junior high school, would anyone expect to have the superpower of flies? ... Fly Man! Imagine, it's really strong.

Reference link:

Https://www.science.org/doi/10.1126/sciadv.abo0719

Https://edition.cnn.com/2022/09/07/world/flies-escape-swatting-scn-partner/index.html

Https://www.hhmi.org/news/complete-fly-brain-imaged-at-nanoscale-resolution

Https://www.bbc.com/news/science-environment-41284065

Https://www.npr.org/2021/01/13/956506208/new-discovery-explains-why-its-so-hard-to-swat-houseflies

Https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2375

Https://royalsocietypublishing.org/doi/full/10.1098/rspb.2020.2374

Https://news.sciencenet.cn/htmlnews/2021/1/451804.shtm

This article comes from the official account of Wechat: global Science (ID:huanqiukexue)

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