The lotus, a radiant and graceful aquatic plant with a magnificent ability to repel dirt, has been the inspiration behind a range of self-cleaning and dirt-repelling technologies. Now a registered trademark, the “Lotus Effect” promises a future filled with objects that rarely, if ever, need washing. Finally, this means owning bathroom mirrors that unfog itself and shirts that shrug off ketchup and coffee.

And the earth, We have spread it out like a couch; and how excellent We are in spreading it. (Adh-Dhariyah, 51:48)

The factory of the universe and the guesthouse of the earth are so pure and clean and so untainted and fresh that … if … the act of cleansing is not attributed to the Creator of the universe, then … [e]ither all the creatures would have a share in the universal act of cleansing… or there would have to be a consultative committee the size of the universe in order to decide and regulate all those acts together… This is impossible not just once, but hundreds and thousands of times over. (4)

Have you ever come across a “stinky forest”? How about a “messy desert”? These questions are primarily posed as rhetoric since various means of sanitation is ubiquitous in nature (Stinky forests and lakes actually exist only thanks to pollution—a modern problem introduced by human intervention via misconduct of technology) where Lotus Effect is only one of the mechanisms contributing to the steady “house-keeping” in nature.

In muddy waters, the lotus plant stands out with its ever-clean leaves making it a symbol of purity in Asian cultures. Moreover, lotus leaves keep dry under even the heaviest monsoon rain. Such seemingly ironical feats are accomplished by capitalizing on a principle named after the plant itself: The Lotus Effect.

The Lotus Effect

At first sight, the cleansing of the leaves by the rainfall seems utterly trivial. However, the cleaning of the lotus plant (Nelumbo nucifera) by the downpour is not something to be taken for granted. Curiously, when raindrops encounter the lotus leaf, they adopt an almost perfectly spherical shape, resembling ball bearings, and start rolling off the surface carrying away all the dirt (Figure 1). Easier said than done, the lotus plant always keeps pristine, even at the microscopic level.

In the early 1970s, soon after the electron microscope (which can yield vivid images of the ultra small details that are at length scales on the order of a billionth of a meter) became commercially available, German botanist Wilhelm Barthlott (of University of Bonn, Germany) started imaging plants using the newly discovered technology. Sample preparations for electron microscopy normally demanded tedious cleaning procedures since even a speckle of dust could ruin the portrayed landscape at such minuscule scales. To Barthlott’s surprise, some plants apparently were “self-cleaning”: They required very little (or sometimes none whatsoever) cleaning for detailed inspection with the microscope and the lotus plant was a prince of these (1). Further intrigued by the fact, Barthlott looked at the lotus leaves through the electron microscope to find out what renders the lotus plant remarkably competent to repel even the tiniest dirt.

Water’s love-hate affair

Before delving into the secrets for lotus plant’s sanitation, let’s look at the interaction of water with other materials. At the molecular level, the electrical charges are unevenly distributed across a water molecule (i.e. water is highly “polar”) which becomes entangled in a love-hate type of relationship with other materials: Some materials “love” water tending to maximize their interaction with it, whereas others “hate” it, trying to avoid their encounter with water as much as possible.1 To put things in perspective, we can immediately tell from everyday experience that oil is “water-hating” since oil and water do not mix, while sugar is “water-loving” because sugar can dissolve in water without much effort.

Macroscopically—that is, one can immediately realize by touching a lotus leaf—the lotus leaf surface feels waxy, and should therefore be water-hating. However, the waxiness is not enough to equip the lotus plant with its unusual capabilities to remain clean since the lotus leaf is not alone among plants in its leaves’ surface waxiness. Indeed, there is more to the lotus leaf’s curious surface properties than that, a property which was first recognized by Barthlott under the electron microscope.

Super water-hating surfaces

When Barthlott looked at the lotus leaf, besides its spotlessness in the microscopic sense, the leaf surface was decorated with numerous bumps a few micron sizes each (a micron is one millionth of a meter). Such bumpiness served to enhance the water-hating aspect of the surface making it “super water-hating,” corresponding to a contact angle that is close to 170 degrees. As a result, water encountering the lotus leaf surface rapidly beads up forming a nearly spherical shape (akin to the scenario when one drips water on a hot cooking pan) and drops roll off the surface even with an ever-so-slight inclination of the leaf. Apparently, a rolling water droplet is much more effective in picking up the surface dirt than one that is merely sliding, and all the surface debris is thus wiped off.

Although discovered first in the lotus plant, the super water-hating surfaces are serving a passive yet effective means of cleaning for animals like butterflies, dragonflies and other insects that are not able to clean all their body parts actively. For plants, preventing the coverage of their leaves by water (or other contaminants) is important to maximize the exposure to sunlight which would otherwise cause reduced photosynthesis. Another great biological relevance of surfaces of such nature for all these creatures is that it provides protection against the growth of pathogens by keeping the surface dry at all times.

Inspirations from biology for technology

There are ever-growing biologically inspired technologies, so-called biomimetics, and the lotus effect provides a nifty example. Unfolding the mystery behind lotus’ exceptional competence in self-cleaning, Barthlott patented the idea of artificially manufacturing microscopically-raised, water-repelling surfaces to mimic the lotus leaf. “Lotus Effect” is now a registered trademark which underlies commercial products such as self-cleaning windows and fabrics, as well as a dirt-repelling paint. Other applications that are waiting around the corner are: swimsuits that stay dry for days allowing prolonged underwater excursions, coatings on metals to avoid the deposits of marine bioorganisms which would enable up to 40% reduction on fuel consumption by decreasing friction (2). Metal coatings will also find applications to prevent ice formation on plane engines alleviating their wear-and-tear (3).

Apparently, lotus does not collect dirt, but only patents.

Note

1 Contact angle is a metric for the water propensity of a surface. Water drop displays a higher contact angle (hence lower contact area) on a water-hating surface when compared to a lower contact angle (hence higher contact area) on a water-loving one.

References

1. Forbes, Peter. August, 2008. “Self Cleaning Materials,” Scientific American.

2. http://www.basf.com/group/

corporate/en/innovations/events-presentations/nanotechnology/basf

3. “Water-Repelling Metals,” Prachi Patel, MIT Technology Review, 2008, http://www.technologyreview.com/energy/21530/

4. “The Thirtieth Gleam,” Bediuzzaman Said Nursi, Risale-i Nur Collection.

Original article: Kim P. et al, ACS Nano (2012, online ahead of print)

Frost formation on aircrafts at high altitudes poses major safety threats and high-maintenance costs. Now, Joanna Aizenberg with her research team present a solution in their recent publication reporting on outstanding capabilities of a surface coating to prevent frost formation on metal surfaces. The technology called SLIPS (Slippery, Liquid-Infused Porous Surfaces) was inspired by the slippery surface of the carnivorous pitcher plant, which enables the plant to capture insects. “Some of the most extreme examples in biology can provide the most amazing and unexpected ideas…” says Aizenberg, who is a professor at the Wyss Institute for Biologically Inspired Engineering at Harvard University. Rendering surfaces slippery is not new to scientists, and the earlier inspirations also came from biology. Mimicking the surface of the leaf of another plant (Nelumbo nucifera, or commonly known as the Lotus plant), scientists have been successful in fabricating surface coatings that would repel water-based dirt, but Lotus-inspired coatings failed for oily substances. On the other hand, Aizenberg’s SLIPS technology offers a single solution for repelling any type of accumulated unwanted material. The pitcher plant thus offers a solution that virtually proves to be the “silver bullet” in generating non-sticky coatings as described again in Aizenberg’s own words: “In following its example, we should be able to develop a platform that works for almost any sticky problem, no matter how seemingly unrelated, whether it’s ice accumulation, bacterial attachment, environmental contamination, clogging of pipes, marine biofouling, or graffiti, rather than having to come up with a host of individual solutions.” Thanks to the wondrous design in the pitcher plant, it looks like doctors will be delivered from replacing bacteria-contaminated arterial stents, and we can all give a kiss goodbye to frosty freezers.

2- Airborne bird flu virus possesses a great risk

Original articles: Herfst S. et al, Science 336, 1534 & Russell C.A. et al, Science 336, 1541.

Science magazine recently published a special issue (June 22, 2012 issue) on the H5N1 infection (a.k.a. bird flu) with two reports revealing the pandemic (a disease prevalent throughout an entire country, continent, or the whole world, such as AIDS) potential of bird flu. Bird flu virus has so far killed millions of birds and many more millions of birds were culled to stop the propagation of the virus. Thankfully, this virus has not yet caused a pandemic in humans mainly because of its inability to spread easily among humans. One mechanism that makes viruses highly contagious is their ability to spread through air, such as through the nose and mouths of people when they cough and sneeze. Viruses that spread through air are called airborne viruses. One big difference between bird flu virus and the more recent swine flu virus (H1N1) was that swine flu is an airborne virus and bird flu is not, and therefore swine flu caused a mild pandemic in 2009. As reported in these studies, researchers identified several genetic mutations that will cause bird flu virus to become airborne. Viruses undergo mutations all the time and unfortunately some of these identified mutations have already started taking place in circulating virus strains. This poses a great risk. One important aspect of these reports is that they were written about a year ago but withheld since now, because of concerns about misuse of this information to pose a threat to humanity. Now that the information is public, our hope is that it will be used to monitor the virus closely and be prepared if bird flu virus transforms into an airborne virus.

3- Not all bacteria are the same after all

Original article: Chung H. et al, Cell 149, 1578 (2012)

The impact of our own bacteria on human life has been intensely researched in recent years. One of the common ground is that humans acquire many useful bacteria over their existence. However, this microbial flora constantly changes as the conditions do. Therefore, the real number of 500 to 1000 microbial species inhabiting mammals is anybody’s guess. Nonetheless, some scientists did not shy away predicting a connection between having a specific microbial flora to avoid certain diseases. A recent article by Chung et al presented an interesting clue why constant change in microbial flora, especially if that leads to a loss of important bacteria, may be linked to the increase in human autoimmune disorders. “For every cell in your body that is you, that contains your specific genetic information, there are approximately nine foreign bacterial cells, primarily in your digestive tract and even on your skin,” said Dennis Kasper, professor at Harvard Medical School and senior author on the paper. To address the question if microbial affects immune system development, authors compared two groups of mice, both of which had never had bacteria in their intestine before the experiment. One group of mice received mice microbial flora and the other received human microbial flora. Both groups had similar number of bacteria in their digestive tracks. However, authors observed a stark contrast between the two groups in terms of the level of immune cells in intestinal tissues. Mice that received human flora had surprisingly low number of immune cells compared to the mice that received mouse flora, which is native to mice. When this experiment was repeated with rat microbial flora, astonishingly, similar immune deficiency was observed. “I was very surprised to see that. I would have expected more of a half-way response,” Chung said, considering how closely rats and mice are related. The study points out that we really need to preserve our own microbial flora that has been tailored for us. Disrupting this balance by means of current antibiotics overuse may have detrimental effects in the future.

Original Article: Gibson, D.G. et al., Science Express (2010).

A team of genome researchers at the J. Craig Venter Institute in the U.S recently announced that after almost 15 years of work and with a budget of $40 million, they had finally built the first bacterial strain with a completely synthetic genome. In the study, researchers chopped the genome of Mycoplasma mycodies into 1,000 pieces in the computer, chemically synthesized these fragments and assembled them into an artificial chromosome in yeast cells. The reconstructed artificial genome was subsequently transferred to a closely related bacterium Mycoplasma capricolum, whose genome was removed. Remarkably, the strain with the artificial genome was able to guide the protein machinery of the host cells, produce the necessary enzymes and macromolecules for a bacterium to survive and most importantly to grow and divide. Team leader Prof. J. Craig Venter, best known for his pioneering efforts in human genome mapping project, commented on their findings as “we created a ‘synthetic cell’ and it is the first self-replicating species we’ve had on the planet whose parent is computer.” Many media sources also publicized the study as the first successful creation of the artificial life. As much as the scientific community agreed that the synthesis, transfer and retention of a functional synthetic genome is a breakthrough, most of the scientists have found Prof. Venter’s comments and the media’s reflection on the study to be somewhat of an overstatement. It would be quite unfair to call the new bacteria an example of “artificial life.” The synthesized genome was a copy of another living bacterium with slight modifications. The genome is a blueprint, whereas the proteins perform the actual cellular functions. This new approach shows that we can copy the book of cellular blueprints reliably but it brings no new parts to our inventory. Moreover, the synthetic genome had to be assembled in live yeast cells, processed with biochemical extracts from mycoplasma cells and finally transplanted into another (closely related) live cell. In other words, “natural life” was absolute prerequisite for the so-called “artificial life.” The generation of a fully functioning organism directed by machine-synthesized genome certainly represents a major step in our ability to manipulate large chunks of genetic material. It is clear that this study will positively influence many scientists, especially synthetic biologists, to try writing novel “synthetic” software to recruit the variety of organisms’ cellular hardware for solving various global problems like energy shortage or environmental pollution. However, the philosophical questions that probe the essence of life, like: “Can we reduce life to material? Is the human being ever going to be able to build a live cell from only a few chemicals?” will likely remain as major controversial issues for many years in the age of molecular biology.

2- Sharing the powers of Spiderman

Original Article: Vogel, M.J. & Steen, P.H., PNAS (published online before print on February 4, 2010).

The adhesive powers of Spiderman, jumping from one building to another and walking on the walls, attracted most of our interests. The recent invention of scientists from Cornell University brings this power from science fiction cartoons/movies to the real life. Inspired from a little creature, leaf beetle, which can stick to leaves by generating a force exceeding 100 times its body weight, these researchers designed a device which can stick to surfaces by using the adhesive powers of water. The device consists of a plate not thicker than a credit card with hundreds of tiny holes on it. The water is pumped through these holes, which builds liquid bridges between surfaces and thus generates a strong adhesive force. Simply pushing back the water un-sticks the device in a controllable and switchable manner. There are no solid moving parts nor any kinds of glue used in the system, and this makes device even more promising. The capabilities of the device are not at the level of the leaf beetle yet, but the inventors believe that it can be improved by building on the same principles. The system can potentially be used in many practical applications, such as robotics, and it can also be implemented into shoes and gloves allowing them to stick to surfaces. Accordingly, it is no longer improbable to imagine sharing the sticky-powers of Spiderman and walking on the walls very soon.

3- Igniting a Supernova

Original Article: Gilfanov, M. & Bogdan, A., Nature 463, 924 (2010).

upernova: the Rosetta stone that may help us put together the missing pieces of the cosmic jigsaw puzzle; one of the most energetic and most luminous explosions in the universe, putting out energies equivalent to what our sun could produce in 10 billion years. Yet the mechanism that produces these explosions still eludes us. Once our sun consumes its remaining fuel in another 5 billion years, it will shrink into a “white dwarf.” These compact stars are believed to produce subsequent explosions leading to supernovas if they reach beyond a critical limit of mass. One way to gain mass is to steal material from a companion star through an “accretion” process. Accretion was thought to be the most common means that might help push the mass of a white dwarf beyond the critical mass limit, until a recent study revealed that two clashing (in-spiraling) white dwarfs might be the missing fuse that ignites supernovas. German astronomers measured the X-ray flux of four nearby elliptical galaxies and the core of the Andromeda Galaxy to see whether the amount of X-rays from these galaxies are consistent with predictions based upon the accretion mechanism. Contrary to expectations, the observed X-rays were 2–3% of the amount that would have been produced if accreting white dwarfs were the primary trigger of supernova explosions. Hence, perhaps merging white dwarfs are more commonplace in the cosmos after all.

4- Strategy of bats finding their way

Original Article: Yovel Y et al., Science 327, 701 (2010).

Bats, dolphins, shrews and swiftlets use sound waves for navigation and hunting. They emit short sonar pulses and listen to the echoes reflecting back from solid objects. Microsecond differences in the arrival times of echoes are coded by detector neurons and used as a main cue for positioning objects in an environment. This phenomenon is known as biosonar. A recent study published in Science reveals one unknown part of this perfect sound processing strategy. The study shows that bats do not center the sonar beam on the target. Instead, they aim to match the maximum slope of the beam to the target in order to increase the signal-to- noise ratio. Around the sharp edge, small variations of the target position can be detected as a clear signal change in reflected sound intensity. Furthermore, the researchers showed that if the environment is very noisy, bats could bias this critical point to increase amplitude of the echoes. This powerful technique has already been employed by humans in engineering and used in various technological tools such as atomic force microcopy. Whether this strategy is used in general by other echolocating animals remains to be answered.

The surfaces of soap bubbles have a very important feature. These surfaces which have minimum surface-tension potential energy also have minimum areas. That is, soap bubbles or clusters have a natural tendency to minimize area for the volumes they enclose. Two different frames and the areas formed are shown in Figure 1. For a given closed frame, at least one such minimal area can be formed; however, mathematicians have had to strive to prove it.

The famous mathematician Richard Courant (1888–1972), together with his students, did soap bubble experiments with various frames.

Minimal areas can also be formed by using more than one closed frames. Figure 2 shows the minimal surfaces obtained by holding two circular frames parallel. If the frames are kept too far from each other, no surface will form. If they are kept sufficiently near to each other, surfaces similar to those shown in Figures 2a and 2b will be obtained. If they are kept close enough to each other, then three minimal surfaces adjacent to each other as shown in Figure 2c can form.

The minimum energy principle is commonly observed not only in living organisms, but also in lifeless matter. A chain will take the shape which produces the least potential energy of attraction when it is fastened at two points onto a rod as shown in Figure 3. This form (function) is called “catenary” in mathematics.

The areas which are formed as a result of rotating the catenary curve around an axis A are called catenoids. Two different types of catenoids are shown in Figures 4a and 4b. As presumed, catenoids are minimal areas and can be obtained by the use of soap bubbles. If such formations were selected and used in everyday utensils, such as glasses, dishes and so forth, ideal shapes which cause the least loss of heat could be designed.

If the katenoid shown in Figure 5a is cut from its edge as shown in Figure 5b and turned by being slightly extended, a helical form or a helicoid will be obtained as shown in Figure 5f. This helicoid also is a minimal surface. Architects have widely used this form in spiral-shaped staircase structures. See Fig. 6.

Fig. 1-Closed frames and soap film surfaces formed1 Fig. 2a&b–Single foam film surfaces over two parallel circular frames1 Plus, the perpetual screw system which is widely in use in technology is also in a form similar to this geometry.

If a cylinder of the smallest volume that can house a helicoid is drawn (Fig.7a) and the lines on which the surface and the cylinder intersect are marked, then a double helix structure (Fig. 7b) is obtained; this is used in modeling DNA molecules which are the genetic codes of living species.

There are two elementary principles related to soap bubbles. The first principle says that if a bubble touches a surface that supports it, it unites with that surface in a way to make 90° angles. The soap bubble on that plain surface forms into a semi-spherical shape and the angle between the bubble surface and the supporting surface will be 90° at every point of contact. The second principle says that if three soap bubble surfaces come together, they form 120° angles along a line. If soap films come together within a tetrahedron frame as in figure 8, then the angles between the lines will be 109° 28′ 16″.

The Steiner problem which is an elementary problem in mathematics can be solved by the application of the 90° and 120° principles. The Steiner problem investigates how n points over a surface can be united in the shortest way by a web. Two transparent surfaces are connected with thin and parallel pins of equal lengths and then dipped into a soapy solution. When it is taken out, soap films will form. These films have a 90° angle with the supporting transparent surfaces and when three soap films come together, they connect at 120° angles with one another.

When observed from above, the intersecting lines between the soap film and one of the surfaces give the shortest web which unites the points in n numbers. How four points are united is shown in Figure 9a and how five points are united is shown in Figure 9b. Someone seems to have equipped lifeless objects such as soap bubbles with the ability to solve complex problems like a math genius.

Periodically repeated minimal areas have been observed on walls separating organic and inorganic substances in the skeletons of certain sea animals like the sea urchin and the starfish. Figure 10 shows the micro structure of a sea urchin’s skeleton. It has calculated that the geometry of its skeleton has perfectly been shaped in such a way as to prevent the extension of possible cracks.

Experiments with soap bubbles have been a source of inspiration also for architects. Such experiments have yielded inspiration for roof and tent designs. The German architect Frei Otto is one of the most eminent names in this regard. Figure 11 shows the minimal areas which Frei Otto managed to obtain by dipping hair-thin threads in soapy water.

In order for such a soap bubble model to be converted into an architectural structure, it is carefully photographed and precisely measured. Later, solid models are made and tested in wind tunnels. The tensile pressures likely to form under loads of wind and snow are measured by special precision instruments. In real structures, thin steel cables having high tensile strengths replace the hairy threads, and transparent plastic and synthetic materials replace the soap bubble film.

Figure 12 shows roof of the Munich Olympic Stadium, Figure13 shows the roof of the Munich Olympic Athletic Arena and Figure 14 shows the roof of the Olympic Swimming Arena in the same city. All these roofs have been designed and erected using the minimal surfaces obtained from soap bubble experiments.

Children love playing with soap bubbles very much; they usually blow a round circle after dipping a wand into soapy water and then watch the bubbles flying out of it. However, it is not only children who play with soap bubbles and soap films. Scientists have, for hundreds of years, been doing experiments with soap bubbles, developing mathematical theories, obtaining various surfaces and transferring the compiled data into technology.

Experiments with soap bubbles have been a source of inspiration also for architects. Such experiments have yielded inspiration for roof and tent designs.

2) These roofs can easily be erected, dismantled and transported to elsewhere, whereas traditional buildings cannot easily be re-located.

3) These structures which are designed according to tensile strengths are very sturdy all over, whereas the tensile pressures of classical buildings are so high that extremely heavy materials such as concrete and brick are used in order to balance the pressure.

The structures of light and strong materials granted to living things are splendid. The lightness and endurance of our skeleton system, the perfect endurance in the stems of slender plants such as wheat and barley, the extremely thin and elastic structure of a fly’s wing, and thousands of similar examples can be given.2 The word of German architect Frei Otto in this subject are expressive: “Biology has become indispensable for architecture.” Witnessing similar perfections also in inanimate structures such as soap bubbles proves that laws in nature originate from the same hand.

Obtaining minimal surfaces has become much easier as a result of immense increases in computer capabilities. Extremely complicated minimal surfaces which can be obtained through computer-aided-designs and calculations have become easily available as alternatives to soap bubble experimentations. If we, as human beings, are aiming to realize developments in science and technology, we should look,more carefully and meditatively, at events which are seemingly simple and unimportant around us and we should also discover the beauties and perfections that God has granted us and put them into service of humanity. The more our designs are compatible with the laws of nature, the higher our chances of success will be.

References

• S. Hilderbrandt, A. Tromba, The Parsimonious Universe, Springer-Verlag, New York, 1996.
• M. S. Polatöz, Tabiatta Mühendislik (Engineering In Nature), Kaynak Publications, Izmir, 2003.
• A. B. Smith, The stereom microstructure of the echinoid test. Special Papers in Palaeontology, 25, 1–85, 1981.

Solar radiation is unpolarized before entering the earth’s atmosphere. Unpolarized light is a mixture of photons having randomly oriented electric fields. According to the simplest theory (Rayleigh), when unpolarized sunlight scatters from atmospheric constituents (gases, aerosol particles, water droplets, ice crystals), it becomes partially polarized, depending on the scattering angle – the angle between the incoming (direct solar) and outgoing (skylight) rays. Unpolarized light can also undergo polarization by reflection off of nonmetallic surfaces such as asphalt roadways, soils, racks, snow fields and water. Therefore, there is an abundance of polarized light in natural environments in various forms. Recently, it has become apparent that animals can take advantage of these rich sources of information in the underwater world, on the water surface, and in the terrestrial habitat that are of celestial polarization patterns. They utilize this polarized light prevailing in their visual worlds in various ways associated with their behavioral tasks like navigation, communication, mate recognition, eggs laying, detection of water surfaces, enhancement of visual power (similar to colors), or perhaps even camouflage.

The skylight compass

The best understood use of polarization is the skylight compass of insects. The orientation of the electric field changes with the position of the sun. This can make the sun as a compass usable even when the sun is obscured. In 1949, Nobel laureate Karl von Frisch discovered that when the sun is not visible, honey bees can orient their flights and communication dances by means of the extensive patterns of polarized ultraviolet (UV) skylight¹. For clear sky, these patterns are quite regular and depend so strongly on the position of the sun. It is amazing to see how these little hard-working creatures come programmed to use them to calculate the sun’s location.

Since von Frisch’s pioneering work, several other researchers investigated polarization vision and found that the polarization pattern of the sky offers many other insect species (desert ants, dung beetles, field crickets, and house flies) a reference for visual compass orientation². For example, desert ants were shown to make long and tortuous foraging walks, but use the sky polarization pattern to return to their nest on a straight line³. They are able to continuously compute their present location from their past trajectory and, as a consequence, to return to the starting point by choosing the direct route rather than retracing its outbound trajectory.Moreover, interestingly enough, researchers discovered that one species of dung beetles navigate by using million-time dimmer polarization patterns of moonlight. Dung beetles use it as an orientation guide to leave their food source in a straight line to avoid aggressive fights⁴. To find out how the beetles are able to use the polarized light of the moon to navigate, researchers observed the beetles under the night sky. On nights when the moon was visually clear, the beetles continued to forage and roll their dung balls in a straight line. On moonless or cloudy nights the beetles could not maintain a straight path.

Reflections from water

In nature, important reflections come from water where the polarization distinguishes between water and other reflective surfaces. Horizontally polarized UV light reflected from the surface of water is the main optical cue for habitat finding by insects living in, on, or near water. Weak UV light emitted by a horizontal surface below flying backswimmers can cause the animals to turn their flight paths vertically downward, bringing them to the horizontal surface⁶. Polarization sensitivity has, likewise, been demonstrated in crustaceans, like in the shore-living water flea Daphnia pulex. These animals were shown to swim toward polarized light, which in nature would lead them away from the shore towards deeper water⁷.

Human activity can have overwhelming effects on the natural environment and man-made objects, such as crude or waste oil surfaces, asphalt roads, glass surfaces, or plastic sheets used in agriculture are unfortunately more attractive to water-seeking polarotactic insects than the water surface itself. This effect can be very dangerous for polarotactic insects as these objects function as insect traps. Researchers have observed that every year, in May and June, swarms of mayflies mate, not above lakes and rivers, but above dry asphalt roads and lay their eggs in vain on dry asphalt roads or car-bodies. The horizontally polarized light from these surfaces mimics a highly polarized water surface.⁸ .

Ocean animals

For many ocean animals, sensing polarization may be even more important than sensing color. One possible use for polarization in the ocean (and elsewhere) is signaling: communicating with neighbors, rivals, and potential partners. Recent discoveries have shown that stomatopods (Mantis shrimps), a sort of shrimp found on reefs around the world, use special body areas to communicate with polarized light (Fig.6)⁹. Polarized light can also be used to ‘break the camouflage’ of aquatic organisms because, although from most viewing angles they match the color of the water behind them, the nature of the polarization is quite different. Researchers have found that transparency of aquatic organism to avoid detection can be broken with the help of polarization sensitivity¹⁰. In their experiment, they observed that squid detect zooplankton prey under partially linearly polarized lighting 70% greater than those achieved under non-polarized illumination.

In summary, polarization is central to most of the animals’ lives. It is abundant in the nature in various forms. Here, we have given only couple of examples of ways of various animals’ exploitation of polarized-light information. It seems, as researches continue, that the already long list of animals utilizing polarized light will get even longer as we learn more about it. Yet, even these mentioned examples above are enough to help us realize how perfectly these small animals have been created, and how well they are taken care of in their daily lives when they navigate, communicate, recognize a mate, lay eggs, detect water surfaces, or perhaps even break camouflage. Here, it seems necessary to observe that “The tiny body of a fly is connected with most of the elements and causes in the universe; indeed, it is a summary of them. If it is not attributed to the Pre-Eternal and All-Powerful One, it is necessary for those material causes to be themselves present in the immediate vicinity of the fly; rather, for them all to enter into its tiny body; and even for them to enter each of the cells of its eyes, which are minute samples of its body.” We refer the interested reader to Said Nursi’s reputable article of “A Treatise on Nature”¹³ and conclude with his aphorism: “He who created the eye of the mosquito is the one who created the sun.”