Within the narratives of saints, the act of “walking on water” stands out as a recurrent wonder. While this situation is contrary to the laws of physics and is of course met with surprise by the listeners, it is a perfectly normal way of life for a group of insects, known as the long-legged water striders (Gerris sp.), who can hover on the water surface of calm ponds and rivers as if they were on land.

These brown insects usually stand still; but they are also created with an ability to act speedily on water and make sudden movements if somehow stimulated. In the process, small waves of water are formed behind them, which spread outward. The question that comes to mind is: How do they stay on the water?

The secret lies in the fact that their body size and legs are created in such a way that they can take advantage of some of the properties given to water. Objects with a specific gravity higher than water sink, substances with specific gravity less than water (such as wood, oil) float. There is a weak force of attraction between the molecules on the surface of the water, but this is a weak force, called surface tension, and it is not strong enough to carry a person.

A water strider weighs only as much as three sesame seeds combined; this is enough to bend water surfaces, but it can’t break them. Thus, the surface tension supports the weight of the water strider (Figure 1). In addition to the body size, the gap between the animal’s feet, that is, the width of the weight surface, is of great importance.

As the surface expands, the pressure made decreases. For example, when a knife is sharpened, the cutting surface is greatly reduced, so it cuts the pressed object even with even slight pressure. But if the cutting surface expands, that is, if the blade becomes dull, it is necessary to press hard to cut. Similarly, if a person tried to walk on water like a water strider, he would need feet as wide as about 10 kilometers to support his body weight, which is about 10,000,000 times the weight of a water strider.

Water striders resemble rowboats on the water. When their legs touch the surface of the water, they are covered with a silvery layer of air. Aquatic travelers have as many as 10,000 very small hairs on one millimeter of their legs. They have hairy legs that are a million times denser than the density of the hair on our head. Air is trapped between these hairs. Moreover, these microscopic hairs are covered with cavities that make them even more waterproof. Made of chitin, these bristles have an important function in increasing water repellency and increase the surface area of the leg, allowing them to stay dry. The layer of air held between the bristles allows them to glide over the water for long distances without sinking. Adult water striders can travel up to 50 times their body length per second during “paddling.” This is equivalent to a human running 100 meters per second.

So, how does a water strider start its first movement? Hydrodynamic theories say that surface waves can only be generated if an animal is able to move its legs fast enough. For movement at constant speed and in a straight line, this minimum speed is 23 centimeters per second, which is low enough to be tested in a bathtub or swimming pool. The legs of the adult ones are one centimeter long, while the legs of juvenile striders are barely one millimeter long. In order to reach the required speed, baby water striders need to rotate their legs at speeds higher than 1000 cycles per second, which is 500 times faster than the speed at which we pedal on a bike, which can damage them. But since it is known that baby water striders can also initiate the first movement and continue it on the water, there must be a different mechanism.

To uncover this mechanism, scientists studied water spiders. It was noticed that spiders, as they move on the surface of the water, produce waves behind them. After this observation, the water travelers were monitored with devices capable of precise recording. The entire stroke of the paddle lasted about a hundredth of a second. (We can fit 30 paddle strokes in a single wink). It was observed that the water striders rowed with such a frequency with their middle legs, being able to move forward and upward. The water surface behind was rippling like a trampoline. But the analysis suggested that the undulating trampoline could not be the only reason pushing it forward.

In the laboratory, it was found that when the paddling of water travelers was followed using colored paints, the waves formed were only a brief image of the paddle stroke (Figure 2). The actual waves that formed were the vibrations generated by the mechanical force that came and went quickly. What really stood out were the butterfly-shaped, bipolar vortices on the back of both legs. Even baby water striders could generate vortexes with the motion of rowing. The forward movement of the water strider is based on pushing a pack of liquid backwards. By pushing the fluid backwards, they were pushing themselves forward and maintaining their momentum.

In order for a hummingbird that flaps its wings suspended in the air to maintain its level, it must constantly push the air downwards at a fairly high speed, since the air is 1000 times lighter than water. The air that is pushed down has a certain momentum, which is equal to the product of its mass multiplied by its velocity. Therefore, in order for it to remain in the air, the momentum, the speed at which it is being pushed downward, must be equal to the weight of the bird. The helicopter works in the same way: Rotating propellers propel the air, accelerating it, thereby increasing momentum, and then pressing the air downwards as compressed as possible.

In order for a fish to swim forward, it must also maintain its momentum. Moving forward, it moves in the opposite direction with the help of its fins and tail, forming a trail approximately its own size. Due to the conservation of momentum, this trail runs in the opposite direction of the fish. The trace that appears in the water usually depends on the style of the movement performed. Birds flying at low speeds create a vortex with each flap of their wings. When the basilisk lizard (Basiliscus plumbifrons) runs through the water, vortices are formed that move backwards as it presses downwards to support its weight and create thrust. Creatures such as birds, fish and lizards that move in the water have been created with the ability to make these vortices.

A water strider can create vortices the size of watermelon seeds. It uses only two of its six legs as a paddle. Since the diameter of their legs is 50 times thinner than the width of the vortex, it is thanks to their surface tension that they are able to move the liquid with their thin legs. When a water strider sits on the surface of the water, it produces pits on the surface of the water. While moving their legs, these pits are maintained without breaks on the surface of the water. Filled with air, but held together by surface tension, pits are like paddles used to catch and push away more water than the insect can do with its slender legs.

The hardest part of building a mechanical robotic water strider is that it has to be light enough to balance on the water. One of the human-like robots is the walking robot named Asimo. He is 130 cm tall and weighs about 55 kilograms. A water strider, on the other hand, weighs one-100th of the weight of a paper clip. Observing the world’s largest water strider, Gigantometra gigas, scientists began to think that there was a way to build a lightweight robot. Gigantometra gigas‘s body is three times longer than that of a normal water strider, and its legs are almost a foot wide. Despite this, it weighs only 1 gram, that is, the weight of a paper clip.

One robotic strider has been produced in lab out of aluminum and with water-repellent (hydrophobic) qualities. Aluminum is known to be amongst the lightest, most durable, and most cost-effective metals on the market (Figure 3).

The excess weight in an aircraft’s fuselage requires longer wings to create lift. Similarly, the heavier the robotic strider, the longer must be its legs to be able to support its weight on the water.

After the robotic navigator was released to the surface of the water, several waves were seen. It slowly slid forward and began to move on the surface of the water.

Inspired by God’s creations, we can find living things in nature to serve as models for many more technological innovations. In the future, it may even be possible for people to walk on water. If we succeed in reading the book of the universe with this perspective, we can develop many innovations that will make human life easier by making use of animals and plants.

Reference

David L. Hu, How to Walk on Water and Climb up Walls, New Jersey: Princeton University Press, 2018.

In 1832, 100 km off the coast of Argentina, Charles Darwin observed numerous tiny crimson spiders, sized 2-3 mm, riding the breeze from the sea and then sticking onto the ropes and sails of the HMS Beagle, the ship on which he was touring around the world. He wondered how it would be possible for so many spiders to reach a vessel as a group that was very far from land. Darwin realized that these insects, which lived on land and did not have any apparent wings, were able to use tiny but extremely strong silk threads as sails or balloons to glide on wind.

These tiny insects could fly up to an altitude of approximately 4,000 meters using this method. The chemical processes involved in the production of the silk threads that are hardly visible to the eye, but are stronger than steel, are a mystery. While we are still unable to manufacture such advanced threads with all our technology, 45,000-50,000 species of spiders known to humankind can easily produce such threads with different characteristics in conformity with their nutrition, movement, and reproduction styles since the day they are created. They use these threads to set their traps for hunting, to build their nests, or moving around by hanging in midair. These diverse silk threads are synthesized from the amino acids in the special silk “laboratories” in the abdomens of spiders.

In order to find new habitats, these tiny spiders climb upwards until they reach the uppermost tip of a branch or leaf and start to release a silky thread like a kite in the direction of the breeze before they take off. They cling to these threads and start to glide through the air as if they are water skiing or paragliding. In this manner they can travel for hundreds of kilometers and, depending on air currents, they may reach altitudes of 500 meters or even 4,000 kilometers. The widespread explanation is that the dragging or lifting force of the wind can help the spider attached to such threads rise in the air. However, existing aerodynamic models fail to fully explain the ballooning mechanisms [1]. Another model proposed uses electric charges in the atmosphere to explain ballooning [2].

The miraculous thread that collects electricity

Amazingly, it has been found that spiders are equipped with the ability to detect electric fields and produce a thread that is charged by electric fields and operates similar to that of a battery. According to the research, the spider produces the special threads that are suitable for the ballooning effect with its sensitive receptors. The spider can also determine the wind direction and force with its mechanosensory hairs and eventually, electric driving force that is sufficient for ballooning is created [3].

In this case, physicists disagree over the main driving force affecting the silk thread: aerodynamic drag caused by the wind; or atmospheric electrostatic force. Based on Darwin’s observations and estimates, the physical force required for ballooning used to be attributed to the aerodynamic drag at the wind speeds less than 3 meters per second since then, but the extent to which electrostatic forces contribute to the ballooning was never tested.

Several problems arise when only aerodynamic drag is used to explain the ballooning process. For instance, in some species, the spider spreads out several silk threads and glues them together to form a fan or web that functions like a balloon. Some other species of spiders are observed to hold on to silk threads separately in order to move around in light breezes. The effects of an electrostatic force repel these threads so that they do not stick to each other. There are also questions about how spiders can release silk threads for ballooning at high speeds despite low wind speeds.

When the mechanism of silk production is examined it is seen that an external force is needed in order to pull the thread out of the pores of the gland during their production. In this case, how is high acceleration, which is required for the initial take-off, achieved when wind speeds are low? Despite reports that thermal air currents and temperature gradations function as a driving force on hot days, ballooning has been observed also on cloudy and rainy days. Models that take into consideration all the conditions such as humidity, temperature, and wind speed have been made but there are still issues that need to be addressed.

Is the spider versed in physics?

The role of electrostatic forces in helping spiders take off has been suspected but has yet to be tested. Eventually, experiments conducted by scientists from the University of Bristol confirmed in a study that spiders both detected electric fields and used them to launch themselves into the air [4]. When they sense a suitable wind spiders climb to the tip of a leaf where the electric charge is highest. They then level their legs, raise their abdomens upward, and start to release the silk thread. As the thread reaches a sufficient length the electric charges of the atmosphere starts to pull. The counteracting force from the earth starts to push the non-conducting thread and thus causes the spiders to take off.

Electric field

The distribution of the electric field in the atmosphere is related to a number of biological systems. For instance, bumblebees can detect the electric fields between them and flowers. Honeybees can use electric charges to communicate within their hives. How widespread is the ability to detect and use electrostatic forces among the organisms living on land? The silk produced by spiders is known as a strong insulator; Michael Faraday used it for the first measurements of electrostatic charge, and it was found that this silk collected a net negative charge.

The next question is to ask how these electric fields are formed. The earth is loaded with negative electric charge and the upper parts of the atmosphere are loaded with positive charge due to thousands of storms that occur every day. This atmospheric potential (voltage) gradation between the earth and the sky exists also on sunny days, albeit at a lower degree compared to stormy days. This event can hardly be brushed over as a simple flight of spiders as it involves more wise purposes than meets the eye.

Scientists have discovered that a spider can sense electrostatic forces and determine whether there are suitable conditions for take-off, and even control its altitude during flight, thanks to the special receptor hairs on its legs (trichobothria). The mechanisms involved in adjusting the thickness and length of the thread through the opening and closing of the silk-secreting nozzles, preparing the amino acid mixture in the correct sequence, and releasing the mixture, which is initially in a liquid form but hardens upon contact with air, are so complex that they cannot be found even in modern nylon yarn production plants.

Tens of parameters, such as the ones listed above, have to be created thoroughly, at the perfect time, in the required quantities, in the required order, and without fail in order for spiders to travel through the air using a parachute- or sail-like system, which they perform as if they were specially trained for that. There are such knowledge, power, will, and wise purpose involved in all these activities that they cannot be attributed to mere chance.

References

1. Humphrey J.A.C. (1987). Fluid mechanic constraints on spider ballooning. Oecologia. 73: 469–477.
2. Gorham, P.W. (2013). Ballooning spiders: the case for electrostatic flight. Archiv, archiv:1309.4731v, arxiv.org/abs/1309.4731.
3. Morley, E.L. and Robert, D. (2018). Electric Fields Elicit Ballooning in Spiders. Curr Biol. 28(14): 2324–2330.e2
4. Ibid.

Think of yourself as a desert ant. You leave your nest to search for food early in the morning in the deserts of Tunisia, except you do not know where to find food. You, therefore, walk randomly in the desert in a circuitous outward path from your nest until you find food. If you would find food, how do you get it back to your home? How do you go back without having left for yourself any traces or signs in the wasteland, without knowing where you located, and most importantly, without ending up stranded in the scorching heat of the desert? Could you accomplish coming back each day with food? Well, desert ants can.

To find out how ants can do this, scientists observed their behavior, and surprisingly they have found that ants did not follow back on the same trail they randomly took after they left their nests. Instead, ants took a direct route as if they already knew where the nest exactly located. How do these ants find the closest way and shortest distance to their nest from their current locations? Former studies had found that red and forest ants secrete a chemical substance to mark their paths. They leave a trail of chemical scents or visual traces behind them—like leaving a trail of breadcrumbs to help you find your way home. However, the structure of desert sands and conditions are not consonant with containing chemicals that will carry an odor or leave visual cues. Even if such markings have made, it is hard to guarantee that they will remain intact long enough considering the harsh conditions of the desert. As in Hansel and Gretel fairy tale kids who could not return home for the breadcrumbs they had left on the trail eaten by birds. Therefore, these desert ants must be equipped with another cognitive mechanism so that they can return to their nests before succumbing to the midday heat.  

Black desert ants (Cataglyphis fortis) emerge from their nests in the heat of desert sand, which rises to 70 degrees with the rise of the morning sun, to search for the remains of other insects that were not as heat resistant as they are. They can only survive for one hour on the hot sand and under the blazing sun, which means that within an hour, they must find their food and bring it back home without getting lost. The journey is quite arduous and dangerous each day. If the slightest confusion occurs and they are not able to return to their nest in time, then it could cost them their lives.

Scientists conducted a series of research in the scorching deserts of Tunisia to find out how desert ants take their food to their nests in the shortest route possible. Researchers first determined an anthill and plotted the terrain around it to set up a coordinate plane. They observed that the ants left their nests very early in the morning to begin their daily search for food, and many of them eventually found grubs that had been planted by the scientists. However, researchers moved the ants to locations that they had not previously been to after the ant began carrying the food back to their nests. The attempt was to understand whether there was a “sign placement system” within the ants. This system would encourage the ant to find its last known location, in this instance where it had picked up, then find its way back home. However, the ant instead began heading directly to its nest. It was as if the ant determined its position concerning its nest and set off for it immediately. This experiment was repeated on many ants numerous times and with the same consistent results. The ants, as soon as they had placed on the ground, moved to the nest relative to there. With a wondrous intrinsic coding of some neurons in their nervous systems, they traveled the distance between their new location and the nest in the shortest way possible. In addition to this, the margin of error was very nominal; they found their nests with a ten percent error in the average distance of 500-meters and with an error of only two degrees in angle. Additionally, a fascinating discovery revealed that the ants could calculate errors in their navigation systems. As they approach their destination, they would make adjustments if they need to by moving back and forth in parallel lines to reach the nest with minimum error.

Scientists determined that desert ants have about a thousand lenses in their compound eyes (remember that a human eye has only one lens) and 80 lenses in each of their eyes that can detect polarized light that comes from different points in the sky. Polarized light occurs when sunlight enters the atmosphere of Earth, hits air molecules and other particles, and then scatters in all directions. This dispersion leads to polarization, and the light that starts to vibrate in many planes begins to vibrate in only one plane. Therefore, the strongest of them is a distinct polarization that always makes a 90-degree angle towards the sun. The lens system in the eyes of desert ants uses this polarization to form a kind of Sky Map. These ants will occasionally stop and robotically move their heads while returning to their nest. This brief period allows the ants to make this sky map by surveying the sky and making a mental note of its layout. Researchers believe that ants can then calculate the direction that they need to travel to return to their nest. They repeat this movement along the way to continually update their sky maps. If they cannot find their home, then they utilize a patterned search method with a set of circular motions. It means that each ant knows how far it is from their nest at every point of their journey.

Then, how do ants find their direction to the nest? Perhaps they were guided by the position of the sun in the sky is. To test this hypothesis, researchers placed a set of mirrors to make ants perceive the sun in a different state than where it ordinarily would be. It observed that the ants changed their directions according to the new state of the sun. However, this finding raised another question; researchers wondered how the time of day would affect the ants since the sun moves across the sky during the day. However, this finding raised another question; researchers wondered how the time of day would affect the ants since the sun moves across the sky during the day.

In another part of the experiment, the researchers caught the ants after they found the bait, closed a box over them, and kept them inside the box for several hours so that they could not see the sun and its movements. It expected that the ants would have trouble finding their way back after they were released since a long time had passed, and the sun was in a drastically different position in the sky. However, they once again returned home by using the shortest distance possible. It understood that the desert ants were aware that time was passing even though they could not see the sun.

We now understand that ants determine their direction home by using the sun, but we still do not know how they figure out the distance they must travel to return to their nest. Researchers have developed three hypotheses to explore this phenomenon. The first hypothesis was the energy hypothesis. According to this hypothesis, the ants were able to know how much energy they needed on the way back by calculating it they had spent until they reached their food. The depletion of their energy meant the end of their journey. An ant loaded with extra weights to test this hypothesis as soon as it reached its food. The scientists thought that if their body weight increased, then they would not be able to strike reach the nest since they would spend more energy on the return trip. However, in this case, it did not affect the ants, and they returned home in the shortest way possible regardless of their weight.

The second hypothesis was the optical-flow hypothesis. In this hypothesis, it believed that the ants had visual memory, and this was how they remembered the way back. To prove this, scientists prevented the ants from seeing their surroundings by blindfolding the ants when they found their food source. However, the blindfold did not prevent the ants from obtaining the shortest distance back home. As a follow-up to this experiment, the researchers placed an extensive television screen in front of the ants showing an endless desert on the television screen to make the ants feel as if they had crossed the entire desert in this simulation. They used various types of simulations, but the result did not change; the ants found their way.

The last test involved the pedometer hypothesis. It surmised that ants could be counting their steps to determine how far they had traveled. To test whether they were doing so, researchers attached stilts made of hair strands to the legs of one group of ants after they found the food. As their legs now extended, they could move with longer scale steps. Another group of ants had their legs cut below the knee, thus shortened to increase the number of steps needed to walk the required distance back. They then observed the return journey of both groups of ants. The results were astounding; the ants with shorter legs had concluded their course before reaching the nest, while the ants with longer legs ended up passing the nest. Thus, it understood that the ants counted their steps according to the distance they traveled.

The findings reveal that the ants are created with an internal system that keeps track of the steps they take and re-calibrates itself on the way back. People make these complex calculations with measuring instruments and by knowing the laws of trigonometry. However, these small creatures find their way directly back without using any tools or computer applications. They do not use their perception to find direction, and they do not use any other directional methods because they all remember direction and distance as they move forward. If you look at this situation, what would be your simplest explanation? You can only have one definition: These little creatures can measure distances and angles precisely by applying mathematical calculations and trigonometry within their conditions. Since the first day of their existence, these creatures show only a few of the shreds of evidence of the divine power created them out of nothing with wondrous systems and superior abilities in their bodies.

I have put my trust in God, my Lord, and your Lord. No living creature is there, but He holds it by its forelock and keeps it under His complete control. Undoubtedly, my Lord is on a straight path (He governs all that exists and carries out His decrees rightly and with absolute justice). (Surah Hud, 56)

The parable of those who take to them other than God for guardians (to entrust their affairs to) is like a spider: it has made for itself a house, and surely the frailest of houses is the spider’s house. If only they knew this! (Qur’an, 29:41)

A prehistoric Greek fairytale says a young girl named Arachne was a superb spinner and knitted the most gorgeous cloth. She dared the goddess Athena to a competition. When Athena saw Arachne’s stunning work, she ripped the cloth and hit the young girl. Disgraced, Arachne committed suicide by hanging herself. Athena regretted and transformed Arachne into a spider, so that she could whirl repeatedly and endlessly. Arachnida is the scientific name for spiders. It comes from the young girl in the famous Greek fairytale.

Although usually feared and disliked by people, spiders in fact make life easy for us by feeding on mosquitoes, flies, and locusts, thus saving our crops and eliminate the need for man-made insecticides which pose environmental problems. Besides, spiders are much less dangerous than people think they are; most spiders are keen to avoid interaction with people and will bite only when wounded or scared. Even poisonous spiders are rarely as dangerous as popular myths would have us believe: though black widows are poisonous, and their bites painful, they rarely kill people. If handled properly and quickly the adverse consequences of a black widow’s bite typically diminish in a few hours, and, after a couple of days’ rest or cessation of activities, the victim will fully recuperate [1].

There are countless features of spiders. But their silk is exceptionally unique and this article covers its various aspects.

Spider silk

Biomaterials, having developed over millions of years, frequently surpass man-made substances in their properties. Spider silk is an exceptionally stringy biomaterial which is made almost completely of substantial proteins. Silk fibers have stretchy powers similar to steel and some silks are practically as elastic as rubber on a weight-to-weight basis. In uniting these two properties, silks disclose a hardiness that is two to three times that of artificial fibers like Nylon or Kevlar. In addition, spider silk is also antimicrobial, hypoallergenic, and completely biodegradable [2].

The power of spider silk, so fragile in manifestation, is astonishingly great. A filament can be outstretched as much as one half its normal length before breaking, and has a tensile strength exceeded only by fused quartz fibers. Fine fibers are sturdier than others, the power to some degree depending on the velocity with which they are pulled out of the spider’s body. The higher the speed, the superior the strength.

Most of the silken fibers are not single fibers but are made up of two or more strings. A thread may be as fine as a millionth of an inch in width but, frequently, it is ten or twenty times as dense, and the assemblage of these threads unsurprisingly creates larger threads of a diversity of thicknesses. Furthermore, some threads are gluey whereas others are not.

Scientific research demonstrates that a single thread of spider silk, thick as a pencil, could stop a 747 Jumbo Jet in flight, and that on an equivalent footing, the spider’s silk is stronger than steel, per unit weight. It has been shown that the dragline silk of the golden orb spider is one of the planet’s hardest threads.

Spiders employ silk for webs, but also for trap lines, draglines, ballooning lines, for egg pouches and nursery nets, for compartments in which to sleep through winter or to copulate, and for entrapping and wrapping their victims. Silk for all these objectives is not accomplished with one kind of gland; there are at least seven distinct kinds. A few distinctive spiders have as many as six kinds and probably have more than six hundred independent glands; others have fewer than this [1].

Mechanism behind the formation of spider silk

A batch of scientists headed by researchers from the RIKEN Center for Sustainable Resource Science (CSRS) have scrutinized spider silk and discovered that a formerly undiscovered organizational constituent is critical to how the proteins form into the beta-sheet conformation that gives the silk its extraordinary power [3]. If humans can cultivate equivalents to spider silk, they could be applied in industrial and medical applications. It is well-known that the beta-sheets in spider silk are significant to its strength, but how the sheets are created is scantily comprehended, making it difficult to produce synthetic variations. It is hard to comprehend the process: the silk is originally produced as soluble proteins, which very swiftly crystalize into a solid form.

To explain this, the CSRS scientists obtained silk proteins using genetically altered bacteria that can generate silk from a golden orb-web spider (Nephila clavipes) and then executed multifaceted examinations of the soluble proteins. They discovered that the reiterating area is comprised of two designs – unsystematic spirals and a design called polyproline type II helix. Their investigations confirmed that the polyproline type II helix is critical for the creation of the stiff construction, which can then be rapidly converted into beta-sheets, letting the silk be swiftly intertwined. Fascinatingly, it was discovered that pH – which is supposed to be significant for the molecular exchanges of the N- and C- terminus areas – does not play a significant role of the foldup of the recurring areas, and that it is rather the elimination of water and mechanistic forces through the silk gland.

According to Keiji Numata, who is a project leader of JST ImPACT and led the research group, “Spider silk is a wonderful material, as it is extremely tough but does not contain harmful substances and is readily biodegradable, so it does not exert any harmful load on the environment” [4]. Numata hopes that this discovery may lead to the production of artificial silk that will prove useful for society.

Analysis of silk

The silk itself is a material identified as a “scleroprotein.” When created in the glands it is a fluid; only when dragged outside the body does it solidify into thread. Once it was believed that contact with air produced the toughening, but it currently looks that the drawing-out activity alone is accountable for the change.

To carry out the exertion done by the glands, a spider is armed with spinnerets, usually six in number. These are as accommodating as fingers; they can be prolonged, compacted, and overall be applied like human hands. In the “spinning field,” where the spinnerets are congregated, single threads are joined into numerous compound threads, and some of the dehydrated threads may be covered with a gluey substance. Thus, a completed thread may be thin or thick, dry or sticky. It may also have the look of a bead-trimmed necklace. For the last kind, the spider spins rather unhurriedly and, drawing out the gluey thread, lets it go with a jolt. The liquid thus is organized in beads spread out lengthwise across the completed line.

The strand known as the dragline may be understood as a spider’s “life line” because it performs as a lifeguard in all kinds of situations. The dragline goes along with the spider, no matter where or how far it journeys, winding out from spinnerets at the back of the body. It forms a portion of the building of webs, it grips its tiny builder firmly in problematic places, and it helps in absconding from adversaries. When a spider is inactive in a web, the dragline enables a rapid descent and escape. It allows energetic chasing spiders to jump from buildings, cliffs, or any tall position with absolute security. [1]  

Benefits of spider silk to us

The silk of the silkworm could be very profitable and marketable. There are, however, challenges. One is the changing thickness of a spider’s strand; the other is that it doesn’t well endure the interweaving process. Housing and feeding large numbers of silkworms is not difficult. But housing and feeding large numbers of spiders? There are enormous difficulties.

Native inhabitants of New Guinea have used spider silk in a variety of conditions. They make fishing nets, traps, and such objects as bags, headdresses that will keep away rain, and caps. These are not formed from single threads but from tangled, warped threads. The aboriginals of North Queensland, Australia, look to spiders for their angling supplies.

Spider silk has been valuable to the manufacturers of such complex instruments as astronomical telescopes, guns, and engineers’ levels. The threads, being exceedingly fine but nonetheless robust, are outstanding for sighting marks. Throughout the Second World War, there was a significant demand for spider thread for surveying and laboratory instruments. Black widow spiders were utilized for the manufacture of this silk.

One drawback to the use of spider silk in industry is that it might slump in a moist environment. To overcome this problem, strands of platinum or etching on glass plates take its place in such instruments as periscopes and bombsights. [1]

Spider’s silk also might have healing properties. Due to its antibacterial properties and because the silk is abundant in vitamin K, it may be efficient at clotting blood. Because of the problems in obtaining and handling extensive amounts of spider silk, the largest known piece of cloth made of spider silk is an 11 by 4-foot (3.4 by 1.2 m) fabric made in Madagascar in 2009. Eighty-two persons labored for a period of four years to gather over one million golden orb spiders and extract silk from them. [5]  

Applications of spider silk

As mentioned, human beings have been using spider silk for thousands of years.

The manufacture of contemporary synthetic super-fibers such as Kevlar (bulletproof material) includes petrochemicals, which adds to pollution. Kevlar is also strained from concentrated sulphuric acid. In comparison, the manufacture of spider silk is totally ecologically sustainable. It is created by spiders at ambient temperature and pressure and is strained from water. Furthermore, silk is totally biodegradable. If the manufacture of spider silk ever becomes industrially practical, it could be a substitute for Kevlar and be used to create a varied extent of articles such as: bulletproof vests, wear-resistant lightweight clothing, ropes, nets, seat belts, parachutes, rust-free boards on motor vehicles or boats, biodegradable bottles, bandages, surgical thread, artificial tendons or ligaments, and backings for weak blood vessels. [6]

Synthetic spider silk [5]

Duplicating the multifaceted settings needed to make threads that are similar to spider silk has been difficult to both research and manufacture. Through genetic engineering, Escherichia coli bacteria, yeasts, plants, silkworms, and animals have been utilized to produce spider silk proteins. Yet, these synthetic threads have diverse, simpler features than those of a spider. Manmade spider silks have lesser and unsophisticated proteins than natural dragline silk, and have subsequently half the diameter, strength, and flexibility.

One tactic is to remove the spider silk gene and utilize additional life forms to generate the spider silk. Canadian biotechnology company Nexia effectively produced spider silk protein in transgenic goats that passed the gene for it; the milk made by the goats comprised noteworthy amounts of the protein: 1-2 grams of silk proteins per liter of milk. To make spider silk, Nexia utilized damp whirling and pressed the silk protein across minor extrusion cavities in order to mimic the performance of the spinneret, but this process was not adequate to duplicate the sturdier characteristics of innate spider silk.

In March 2010, investigators from the Korea Advanced Institute of Science and Technology was able to produce spider silk by means of the bacteria E. coli, altered with definite genes of the spider Nephila clavipes. This tactic removes the necessity of milking spiders.

It should be noted that the manufacture of spider silk is not easy and there are intrinsic difficulties. First of all, spiders cannot be cultivated like silkworms since they are flesh-eaters and will merely eat each other if in proximity to each other. The silk produced is very slight, so 400 spiders would be required to make only one square yard of cloth. The other problem is, silk also toughens when subjected to air, which makes working with it problematic.

A different tactic is to study how spiders whirl silk and then replicate this process to make artificial spider silk. The silk itself would also have to be synthetically produced. Chemical production of spider silk is not feasible at present due to the absence of information about the makeup of silk. Randolph V. Lewis, Professor of Molecular Biology at the University of Wyoming in Laramie, has introduced silk genes into Escherichia coli bacteria so that the recurring sections of spidroin 1 and spidroin 2 efficaciously come to form. Others theorize about the likely gene introduction into fungi and soya plants. It may also be possible to modify the silk genes for precise intentions.

Why a spider’s house is the frailest of houses

Spider silk is stronger than steel, but the Qur’an (29:41) states that the flimsiest of houses is the spider’s house. The per unit weight of the dragline silk of the golden orb spider is one of the world’s hardest fibers. Webs are combinations of many kinds of spider silk, all able to be produced by the same spider. The web radials are strong, but the somewhat feebler circumferential (quasi-circular concentric) fibers are flexible and gluey to absorb the energy of a flying insect and hold it in place. The strongest of all is the fiber, which the spider uses for transport, the dragline silk. In summary, the spider fabricates both sturdy as well as feeble fibers and the web it weaves to catch flying insects is weaker; this may be the reason why it is referred to in the Qur’an as the “frailest” of houses.

Conclusions

Scientists are foreseeing many potential uses for biosilk. Textile usages are noticeable one. The flexibility and potency of prevailing merchandises such as spandex and nylon have to be improved. Since it is lightweight, hardy and flexible, biosilk may also have uses in satellites and aircraft. More prominently, the new group of progressive things that spider silk investigation may cause has the prospective to alter our lives in innumerable manners that we can barely imagine. More than 72 years have passed since the inventions of Wallace and Carothers that gave the world nylon that led us into the age of polymers. Artificial spider silk may help produce super-performing clothes of the future. Earthquake resistant suspension bridges hung from cables of synthetic spider silk fibers may someday be a reality. [1]

References

1. Syed, I. B. : Spider Silks http://www.irfi.org/articles/articles_1_50/spider_silks.htm
2. Romer, L and Scheibel, T.: The elaborate Structure of spider silk, PRION, Oct-Dec. 2(4) 154-161, 2008. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658765/
3. RIKEN Center for Sustainable Resource Science (CSRS). Scientists discover key mechanism behind the formation of spider silk. Materials Science. May 29, 2018, https://phys.org/news/2018-05-scientists-key-mechanism-formation-spider.html

4. Nur Alia Oktaviani, Akimasa Matsugami, Ali D. Malay, Fumiaki Hayashi, David L. Kaplan, Keiji Numata, “Conformation and dynamics of soluble repetitive domain elucidates the initial β-sheet formation of spider silk”, Nature Communications, 10.1038/s41467-018-04570-5 https://en.wikipedia.org/wiki/Riken
5. Service, Robert F. (18 October 2017). “Spinning spider silk into startup gold”. Science Magazine, American Association for the Advancement of Science. Retrieved 26 November 2017. https://en.wikipedia.org/wiki/Spider_silk
6. Vivienne Li, University of Bristol, Spider Silk and Venom. Molecule of the Month – July 2002. http://www.chm.bris.ac.uk/motm/spider/page4.htm

We classify each living thing by the different and similar features they possess. Through such classifications, we understand that all things are created for a purpose. They help us to read the book of nature laid before us.

Many species of animals belonging to groups such as one-celled organisms, fish, invertebrates inhabiting the seas, and worms in the earth, are still waiting to be discovered. No one can know for sure what the total number of animal species will be. Time will show whether it will be two million, or three, or even five. The number of animal species identified and named to date is about 1,400,000.

Of these, insects number nearly one million species. The group called Coleoptera, or beetles, have the most species, with about 350,000. The next largest groups are Lepidoptera, or moths and butterflies (about 120,000); Diptera, or flies (120,000); and Hymenoptera, or ants and bees without 110,000 species.

Incredible numbers from the insect world

Many insects serve a vital role for humans. Bees, of course, are a great gift to humanity. They do not only serve us honey, but also have a duty to pollinate flowers, fruits, and vegetables. If it were not for the bee, we would not have many types of fruit we enjoy today, or we would find them with difficulty and at exorbitant prices because they would have to be pollinated artificially. To be able to produce honey as small as one gram, a bee, which covers an approximate distance of 800 km in its lifetime, has to collect nectar from as many as 125,000 flowers. Put differently, in order to make one kilogram of honey, 40,000 bees have to visit 6 million flowers.

The animal with the longest jump

If we asked which could jump longer, a kangaroo or a flea, many would underestimate the flea. Striking findings emerge when we compare distances with body size. While a man can leap a distance of five times his height, the red kangaroo can jump 13.5 meters, which translates as nine times its height. The springbok, a medium-sized antelope living in Africa, can jump 10 times its height, a grasshopper 20 times, a kangaroo mouse 45 times, the northern cricket frog (Acris crepitans) 36 times, and a cat flea (Ctenocephalides felis) 200 times. It is a very special protein called resilin, placed in the muscle fibers in the hind legs, with which the cat flea is enabled to jump such incredible distances.

The animal with the fastest wing beat

Despite their tiny sizes, insects are equipped with most mind-boggling craftsmanship. They have keen senses as well as membrane-like wings that can beat shockingly fast. The common fly beats its wings 180-330 times per second, the worker bee 240-250 times, and the mosquito 278-307 times. Meanwhile, the tiny midge called Forcipomyia beats its wings 1,046 times a second, as calculated in 1953 by Sotavalta, a Polish researcher who used an oscillator for the task. Researchers were startled by how electrical and chemical processes could generate the speed required by contraction and relaxation of muscle fibers.

The eye that can perceive the most subsequent movements

For the perception of movement, the eyes need to record slices of movements, one after another, and send them to the brain. The more the number of movements sent in a second, the faster the perception of the movement. While the brains of some animals can handle a few images at a time, others can process a torrent of them. The fire salamander can perceive and process 5 images a second, a human being and a gecko 20, the black beetle 20-30, the cat 27, the frog 48, the bee 55, the rock pigeon 148, and the dragonfly (Libellula sp.) 300.

The animal with the shortest lifespan

Mayflies (Ephemeroptera) are best known for the fact that they spend 99% of their lives as larvae. They spend this period of youth in water, and then they emerge as adults. The length of their adulthood is normally one day. Some may live 3-4 days, and others die in a few minutes. Adult mayflies cannot nourish or feed because parts of their mouths and digestive system atrophy. They start to fly as soon as they are of age so that they can mate. The males die immediately after fertilization and are followed by females (after they lay eggs). Some can produce one generation, some two, and others many. They store all the air they breathe in a day in their intestine and swell their body, and they use the energy necessary for flying from previous reserves.

The animal colony with the largest population

The nests of social insects such as bees, ants, and termites are like plants that operate in the most incredible order. The perfectly designed division of labor includes such groups as drones, queens, workers, cleaners, babysitters, soldiers, guards, etc. The Bellicositermes have the highest population with three million members. A red wood ant (Formica rufa) nest has 500,000–800,000 members, a leaf-cutter ant (Atta) nest 600,000, a termite nest (Reticulitermes) 100,000, a honey bee hive 40,000–80,000, and a wasp nest (Vespa) 700–1,500.

The biggest insect

Because breathing is carried out by the trachea system in insects, it becomes difficult for oxygen to reach the tips of tubes past a certain distance. That is why insects cannot grow very large. The biggest insect in the world is Phobaeticus chani, a species of stick insect, with its abdomen reaching a size of 35.7 cm (~14 in). Measured from the tips of its legs, it has a length of 56.6 cm (~22 in). The insect with the largest wingspan is the Thysania Agrippina, a butterfly species with a relatively smaller abdomen. The butterfly species with the largest wing surface is Coscinosera hercules with a smaller wingspan (28 cm or 11 in) but a wide surface area of 300 cm².

The keenest sense of smell

Sense of smell plays an important role in many types of behavior such as finding prey, recognizing young, and marking the nest. Smell is perceived when chemical molecules dissolved in the air pass through the nose, which varies according to the species of animal. The more the molecules in the air and the closer the distance, the easier is for the scent to be detected. The most skillful creature in this area is Saturnia pavonia, or the small emperor moth. German researchers proved in an experiment they conducted in 1961 that the male moth could detect a single molecule of a chemical secreted by the female into the air with the help of the chemical receivers placed in its fan-like antenna.

The deadliest animal

Animal documentaries mostly highlight the number of casualties caused by such animals as sharks and the venomous box jellyfish at sea, crocodiles and hippopotamuses in fresh water habitats, lions and elephants in savannahs, bears in forests, and scorpions in deserts. These animals are known to be dangerous because they are easy to see with the naked eye and some can be violent. Yet, the total number of casualties by all these animals combined, we can have a better understanding of the overemphasis. These numbers are especially dwarfed by the death toll (around 2.5 million) caused by the much smaller mosquito (Anopheles sp), which holds the title for the deadliest animal. Malaria, yellow fever, West Nile virus, lymphatic filariasis, and dengue fever, all of which are transmitted by this species of mosquito, pose the most serious health threat in many countries of the world.

The animal with the hugest appetite

The intake of an animal depends on its basal metabolic rate, body temperature (warm-blooded or cold-blooded), and the surface area of its body. The food intake of the anaconda snake amounts to 0.13% of its body weight. It is 1% for the Asian elephant, 2.9% for the lion, 3.5% for the chicken, 3.5% for the little owl, 18% for the goldcrest, 30% for the Eurasian blue tit, and 40% for the rat.  The lesser mole eats as much as its bodyweight (100%), while the hummingbird and pygmy shrew consume twice as much. Much smaller than these animals, mosquitoes suck blood four times their bodyweight. The record, though, is owned by a caterpillar called Anthereaea Polyphemus, which eats plants 86,500 times its bodyweight in 56 days and 1500 times in a single day. If a human baby of 3.5 kilos ate proportionally, it would mean 301 tons of food.

The greatest endurance against G-forces

In an experiment, the click beetle (Elateridae) jumped to a height of 29.8 cm (11.7 in). It was found that it its brain endured a deceleration of 2300g by the time it reached its peak. Even jet pilots can only endure a force of 9-10g, meaning their bodyweight is multiplied by 9 or 10. When the racing driver David Purley crashed into an obstacle at a speed of 174 km, he was subjected to 180 g produced by the deceleration. He survived but and sustained dozens of fractures, a few dislocations, and several obstructions in the heart.

The smallest insect

It was first discovered in Nicaragua in 1999, but because there were not enough samples it was not introduced to the world of science until 2015 when Russian researchers demonstrated 85 samples found in a national park in Columbia. Named featherwing (Scydosella musawasensis), the beetle species won the title of the tiniest animal. The smallest of the samples collected was 0.325 mm; the biggest was 0.352 mm. Having an elongated, oval, yellowish-brown body, the beetle has antennas split into 10 parts. It is incredible that this beetle has a heart, a brain and a stomach despite its size of one third of a millimeter.

The earliest records belong to ancient China. In 1235 Sung Tz’u, a Chinese “death investigator,” wrote a book entitled The Washing Away of Wrongs (translated by McKnight, 1981) in which what was known in forensic science at that time was detailed. In this text, an actual forensic entomology case was recounted, with the best known historic case being given. A murder had been committed in a little village in China. A man had been hacked to death with a rice-harvesting sickle. Because the village was one where rice was grown, everyone possessed a sickle, which meant that there were therefore many suspects. A professor at UC Davis, Robert Kimsey, explains how the murderer was caught; “The local magistrate very cleverly lined up every one of the farmers with their sickles out in the field. He walked up and down the line and pointed to the man who had committed the murder. The evidence he used to identify this man as a murderer-who later confessed, by the way-was the fact that green bottle flies were attracted to this man’s sickle. And nobody else, of course, had green bottle flies on their sickle because the flies were only attracted to a surface that had blood on it. No matter how rigorously you cleaned your sickle, you would still have remnants which these flies would be able to detect.”

Since those times, forensic entomology has made great progress. The way insect evidence helps justice works through the successive colonization of a corpse by a predictable succession of arthropod species. Different types of insects start coming right after death occurs. Organic remains, like flesh, blood, waste material, bone marrow, and hairs all attract certain types of insects. Owing to the time difference between the decaying body parts, the flies arrive at different times. They consume the parts that are nutritious for them and leave the body for another group.

As a manifestation of the divine name Quddus (the All-Holy), dead bodies decompose and nature is kept clean. Thus, the process started by microorganisms is made faster by the insects. Blow flies are among the first group of workers in this respect, whereas the dermestids, for instance, do their duty in the later stages of decomposition. The larvae of dermestids are not found before the body dry outs. The larvae and adults feed on dry skin and hair, as well as other dry dead organic animal matter. Dermestids are a common pest in homes, as well as being undesirable in insect collections and taxidermists collections at museums.

The first month after death is the most effective time for the application of forensic entomology. When death takes place, the insects start to arrive within minutes. However, it should be noted that insect evidence does not always tell us about the exact time of death. But at least we can infer that death occurred at a time that is greater than the age of the larvae that are developed in the body. If we have sound knowledge about the life cycles of the relevant insects, we can make more accurate predictions.

Another thing entomology helps us find out is the location of a murder. Sometimes a victim is moved after a murder in order to get rid of important evidence. For instance, a victim can be taken to a mountainous area after being killed in a town at low altitude. Entomologists can tell you about the habitat of the insects found on the body and give one a good idea about where the murder took place. Many insects live in very special geographical conditions. The altitude, temperature, and vegetation all affect the types of insects that live in the area. Furthermore, a meticulous entomological study will tell you whether the body has been, moved, the season in which it was killed, and whether the murder was committed indoors or outdoors.

Entomologists even help forensic experts with the cause of death. Particularly when the body has already decayed, it can be difficult for the police to determine the cause of death. In normal conditions, insects lay their eggs in certain parts of a body. If there are open wounds however, they will also lay their eggs there. So, if any eggs are found in unusual spots they indicate a probable wound.

When a murder or suicide is suspected to have resulted due to poisoning and if the body is decomposed, toxicological analyses that are made on the insects or the larvae taken from the body can help.

Bergeret (1855), who resided near Paris was the first westerner to use insects as forensic indicators. The body of a baby was found behind the plaster mantle in a house, and an investigation was begun. Bergeret determined that the assemblage of insects associated with the corpse pointed to a state of decay that dated back several years; consequently, the question of guilt was thrown upon the earlier occupants of the house, and not upon the current ones.

Case histories have documented the utility of medicocriminal entomology and point out the unique contributions that this field of science has made. Nuorteva et al. (1967, 1974) presented a series of cases from Finland in which blow flies were used as indicators for indoor as well as outdoor death scenes, and where the immature (larval) or adult stages were used for identification. Leclercq (1969) provided a typical case scenario and outlined how insect data were used to corroborate information obtained from other sources. Bernard Greenberg (1985) outlined several cases, including a description of how laboratory fly-rearing data were used to calculate the number of accumulated degree hours (ADH) required for certain blow fly species to develop, and how such data were applied to the solution of a murder case in Illinois. In another recent case, Greenberg described how the absence of insects in a seemingly straightforward death scene led to a killer’s confession. A window next to the victim had been open when the body was found, thus giving the impression that the murderer had forced entry into the room the night before. However, the air conditioned room was cool, even though it was very hot outdoors. In reality, the killer was known to the victim, had a key, and had returned to “set the stage,” opening the window just prior to feigning discovery of the corpse. The insects thus had insufficient time to colonize the body as the window had been closed prior to the return of the killer. When confronted by this biological reality as pointed out by medicocriminal entomology, the killer confessed.

A Hungarian ferry skipper had been condemned to life imprisonment for the murder of a postmaster, whose stabbed body had been found one evening in September on the ferry. The ferry skipper had arrived at 18:00 that day, and the body of the murdered postmaster had been found some hours later. The autopsy was performed the next day at 16:00. Masses of yellowish fly eggs and numerous newly hatched larvae of 1 to 2 mm in length were present, and the findings were recorded in the autopsy report. No attention was paid to this observation at the trial, however. On assumed evidence, the ferry skipper was condemned to life imprisonment in spite of his swearing that he was innocent. Eight years later the case was reopened. At the new trial, Dr. Mihalyi pointed out that no sarcophagous flies are active in Hungary after 18:00 in the month of September. He also recalled some of his experiments indicating that, at a temperature of 26 degrees Celsius, the yellowish eggs of Lucilia caesar (L.) hatch after 13 hours, those of L. sericata (Meigen) hatch after 10-11 hours, and those of Phormia terranovae Robineau-Desvoidy 14-16 hours after oviposition. These data, when applied to the case of the ferry skipper, led to the conclusion that it was not possible for the eggs to have hatched if they had been laid during the day the autopsy was performed, and that they must have been laid during the previous day before 18:00, since the flies are not active after this time. Dr. Mihalyi’s data on oviposition was verified and, on the basis of this and other evidence, the ferry skipper was released from prison.

Entomology, along with other sciences whisper in our ear that in “the Book of the Universe” there are different signs that lead us to the truth; they are there for us to use if we search for them and fulfill the requirement of causes. This is when the world will open its mysteries to us.

Reference

• http://www.ucdmag.ucdavis.edu/su99/Feature_Bugs.html
• http://www.research.missouri.edu/entomology/chapter1.html#history
• http://folk.uio.no/mostarke/forens_ent/casehistories/ferry_skipper.html
• The illustration is taken from the poster of the annual Insect Fear Film Festival at the University of Illinois, Feb. 2005.