How can a midge manages to beat its wings 1,000 times a second? How does a flea leap hundreds of times its own height?
Why does a butterfly fly forwards when its wings beat up and down?
The fly is one of the creatures referred to in the Qur’an, as only one of the many animals that reveal the infinite knowledge of our Lord. Almighty Allah speaks of this matter in verse 73 of Surat al-Hajj:
O humanity! A likeness has been made, so listen to it carefully. Those you call upon apart from Allah are not even able to create a single fly, even if they were to join together to do it. And if a fly steals something away from them, they cannot get it back from it. How feeble are both the seeker and the sought! (Surat al-Hajj: 73)
Despite recent research, despite all the technologies that Allah has placed at the disposal of humanity, a great many characteristics of living things still preserve their miraculous aspects. As in all things that Allah has created in the body of a fly gives abundant evidence of a superior knowledge. By considering its intricacy, any thinking person can once again reflect on his deep respect for Allah and devotion to Him.
Some of the investigations that scientists have carried out on the flight systems of flies and other small insects are detailed below. The conclusion emerging from this is that no haphazard, trial-and-error force or entity other than Allah can have created the complexity of even a fly.
The flight muscles of many insects such as the locust and dragonfly contract powerfully as a result of stimuli emitted by the nerves that control their every movement. In the locust, for example, signals sent by each nerve cause the flight muscles to contract. By working alternately, not against each another, two complementary groups of muscles, the so-called elevators and depressors, allow the wings to rise up and beat down. Locusts beat their wings 12 to 15 times a second, and in order to be able to fly smaller insects must beat theirs even more rapidly.
Honeybees, wasps and flies beat their wings from 200 to 400 times a second, and in midges and some parasites only 1 millimeter (0.03 inch) in size, that rate rises to an astounding 1,000 times a second! Wings beating too fast for the human eye to see have been created with a special structure in order to exhibit such sustained performance.
A nerve is able to send at most 200 signals a second. Then how can a small insect able to beat its wings 1,000 times a second? Research has established that in these insects, there is no one-to-one relationship between signals from the nerves and frequency of wing beats.
Bluebottle flies beat their wings 200 times a second, but their nerve and muscle structures are very different from those of locusts. Only one signal comes from the nerve for every 10 wing beats. In addition, these so-called “fibrous muscles” work very differently compared to locusts.
Nerve impulses regulate only the muscles’ preparations for flight. Once the muscles achieve a specific tension, they contract of their own accord.
In these special systems, created independently in the body of every insect, there is not the slightest irregularity. Their nerves never emit an incorrect signal, and the insects’ muscles always interpret them correctly.
In such species as flies and bees, the muscles that allow flight are not even attached to the wing base! Instead, they attach to the chest by joints that serve as a kind of hinge, while the muscles that lift the wing upwards are attached to the upper and lower surfaces of the chest.
When these muscles are contracted, the chest surface flattens and draws the wing base down. The lateral surface of the wing provides a support function and permits the wings to rise. The muscles establishing downward movement are not attached directly to the wing, but operate along the length of the chest. When these muscles are contracted, the chest is retracted in the opposite direction, and the wings are thus drawn downwards.
The wing joint is formed of a special protein known as resilin, which possesses superb elasticity. Since its features are far superior to those of natural or synthetic rubber, chemical engineers are trying to reproduce this substance, in laboratories. In flexing and contracting, resilin is able to store almost all of the energy exerted on it; and when the force pressing on it is lifted, it is able to give back all that energy.
As a result, resilin is up to 96% efficient. During wing lift, some 85% of the energy expended is stored for later; this same energy is then re-used in the downward movement that provides lift and propels the insect forward. Its chest walls and muscles have been created with a special structure to make possible this accumulation of energy. However, the energy is actually stored in the joints consisting of resilin.
It’s of course impossible for an insect, by means of its own efforts, to equip itself with such an extraordinary mechanism for flight. The infinite intelligence and might of Allah has created this special resilin in the insects’ bodies.
For smooth flight, straight up-and-down wing movement alone is not sufficient.. In order to be able to provide lift and propulsive force, the wings must also have to change their angle of motion during every beat. Insects’ wings possess a particular rotational flexibility, depending on the species, which is provided by their so-called direct flight muscles (or DFMs, for short) that produce the forces needed for flight.
When insects seek to climb higher in the air, they increase their wing angle by contracting still further these muscles between the wing joints.
Fast-frame and stop-motion photographs have shown that during flight, the wings follow an elliptical course and that for each wing’s cycle, its angle alters systematically. This variation is caused by the changing movements of the direct muscles and the wings’ attachment to the body.
The greatest problem faced by very small insect species during flight is air resistance. For them, sheer air density becomes an obstacle for these creatures that can’t be underestimated. Moreover, a restrictive layer around the wing causes the air to clingto the wings, leading to a loss in flight efficiency. In order to be able to overcome that air resistance, flies such as Forcipomya, whose wings are no more than 1 millimeter wide, must beat them 1,000 times a second.
Scientists believe that theoretically, even this speed is insufficient to keep these insects aloft, and that they must employ some other additional system. In fact, Anarsia, a kind of parasite, makes use of a method known as “beat and shake.” When its wings reach the highest point in their lift, they strike against each another and then open down again. As the wings, with their string vein, open the front air current first sets up a vortex around the wings and assist with the wing beat lift force.
Many species of insects, the locusts included, take note of visual data such as the line of the horizon to determine their direction of flight and eventual destination. For determining their position, flies have been created with an even more extraordinary structure. . These insects have only a single pair of wings, but to the rear of each, there is a knob-shaped lobe known as the halter. Although the halters produce no lift force, they vibrate together with the front wings. When the fly changes its direction of flight, these wing extensions prevent it from deviating off course.
All the information provided here results from studies into the flight techniques of just three or four insect species. Bear in mind that the total number of insect species on Earth is around 10 million. Considering all these remaining millions of species, along with the countless features they contain, one must increase still further one’s amazement at the infinite might of Allah.
A Solution to Venous Disorders from the Flea Gene
Scientists have succeeded in separating out the resilin gene from fruit flies and managed to reproduce this protein naturally by injecting the gene into a Escherichia coli bacteria.
In the course of one study carried out by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), scientists who succeeded in identifying the gene that produces insects’ resilin also identified a powerful polymer that may prove useful in the treatment of vein diseases. Studies that began in the 1960s, concentrating on the desert locust and dragonfly, were a powerful factor in advancing this most important step.
Resilin, which also gives fleas the ability to make their enormous leaps, gives these and other insects an astonishing capability of movement. Thanks to this substance, fleas are able to jump many hundreds of times their own height and some flies are able to beat their wings over 200 times a second.
The protein obtained from resilin is far better than the highest-quality rubber products in its ability to resist pressure and revert to its former shape. Continuing experiments on artificial resilin show that the protein still maintains these features.
Scientists state their belief that the polymer obtained from cloning insects’ genes can be employed in a variety of very different fields, from medicine to industry. But perhaps the most important of these applications will be treating arterial disease in humans. Because resilin resembles the protein elastin in human veins, scientists hope that their studies will endow veins with renewed elasticity.
The British Professor Roger Greenhalgh states that “This research [into resilin] seems to be at a very early stage, but if we could take something good out of the elasticity of the flea that benefits humans, that would be most impressive.”1
References:
"Synthesis and properties of cross linked recombinant pro-resilin,"; by Christopher M. Elvin, Andrew G. Carr, Mickey G. Huson, Jane M. Maxwell, Roger D. Pearson, Tony Vuocolo, Nancy E. Liyou, Darren C. C. Wong, David J. Merritt and Nicholas E. Dixon, Nature 437, 999-1002 (13 October 2005) | doi: 10.1038/nature04085; "Flea protein may repair arteries" BBC News, October 12, 2005