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Cobweb is the secretion of the arachnoid glands, which soon after secretion hardens in the form of threads. By chemical nature, it is a protein similar in composition to insect silk. This protein is enriched with glycine, alanine and serine. Inside the arachnoid gland it exists in liquid form. When isolated through numerous spinning tubes, opening on the surface spider warts, a change in the structure of the protein occurs, as a result of which it hardens in the form of a thin thread. Subsequently, the spider weaves these primary threads into a thicker web fiber.

The most well-known use of webs by spiders is the construction of trapping networks, which, depending on the structure, can completely immobilize prey, impede its movement, or only signal its appearance. Spiders also often wrap their caught prey in a web.

Spiders spin webs, which play a very important role in their lives, and find a variety of uses for them. These are spider cocoons, where tiny babies develop from eggs in warmth and safety; and lifelines, like climbing ropes, that attach to plants and prevent the spider from falling to the ground. From the web, spiders make nests for the winter and, finally, weave trapping nets.

Spiders can spin different threads for different purposes. If you need a thread for a fishing net, then special glands located next to the arachnoid glands cover it with a layer of adhesive substance. To move from place to place or to attach a trapping net, a dry thread is produced. Other glands secrete substances from which the thread for spinning the cocoon is spun. The thread of the web is stronger than steel wire of the same diameter and can stretch another third of its length without breaking. To avoid getting caught in its own trapping network, the spider constantly produces a little dry thread. He knows well where the safe areas are, and, hiding in one of them, patiently waits until the victim falls into the net. In addition, the spider's legs secrete an oily substance, thanks to which they do not stick to the web.

the spider begins to weave a web, throwing the thread into the wind. The silk flies in the wind and clings to an object, such as a tree branch, which allows the spider to climb up this thread and add another thread to the original one to make it stronger. After the spider has made the general outline of the web, it spins a thread connecting one side of the web to the other. From the center of this connecting thread the spider begins to weave another thread, which will connect the center of the web with the side thread.

Then the spider will lay a lot of connecting dry threads from the edges of the web along its radii to the center, like spokes in a bicycle wheel. Then these “spokes” are woven with circular threads. The result is a spiral dry web. Then an adhesive thread is applied to the surface of the dry web. Now the spider gets rid of the dry web and eats it. The fishing gear is done, the insect snares are ready.

Spider silk- unusual material. One of its features iswith the unusual lightness of the web- enormous strength.The breaking force, expressed in kg per 1 mm2, for spider webs ranges from 40 to 261, and for caterpillar and artificial silk, respectively, does not exceed 43 and 20.A pencil-thin thread of silk can stop a Boeing 747.

Back in the seventeenth century, engineers drew attention to the web, namely, to the fact that it is an extremely rational mechanical structure that works in tension in such a way that all the threads are in the most favorable conditions from the point of view of the strength of the material.

Any disturbance in the nervous system of spiders is immediately reflected in the pattern of the web. The spiders were given various substances, and each time they wove their own special pattern, which strictly corresponded to a specific substance.

This discovery was unexpectedly useful in forensic science. By giving a spider a drop of the blood of a person who is suspected of being poisoned, the nature of the pattern can determine the poison with which the person was poisoned.

Why doesn't a spider get entangled in its web the same way its victims get entangled in it? And this happens because the spider always runs only along smooth radial threads, and never along sticky, concentric ones.

The oldest fossil web with attached insects was found in Spain (in a piece of amber), which is 110 million years old.

Spiders are very sensitive. The weather can be predicted by their behavior. If spiders develop vigorous activity in the evening, wait for good weather. If this happens in the morning, the weather will be stormy.

The chemical composition of the web is close to the silk of butterfly caterpillars. From the webs of nephil spiders, which are found on tropical islands, the Chinese made a durable fabric called “Eastern Sea Satin.” In Europe, beautiful clothes were made from spider webs.

Polenisian fishermen use the thread of the golden orb-weaving spider as fishing line.
Some tribes in New Guinea used nets as hats to protect their heads from the rain.

The weight of the web is such that if the web were to wrap the Earth once around the equator, its weight would be only 450 grams

Why does a spider need a web?

Most people think that spiders only use silk to spin their webs. In fact, rarely does any animal use silk as versatile as the spider, which makes houses out of it, weaves “life lines”, “diving bells”, “airplanes”, lasso, elastic traps and the well-known web.

Spiders are not insects, but belong to the class of arachnids. Unlike insects, they have eight legs, in most cases eight eyes, no wings, and a body divided into two parts.

Spiders are found in almost any climate. They can run on the ground, climb trees and even live in water. And for this they need a web...

The spider produces different types of silk: sticky silk for the web, which is supposed to catch insects, durable and non-sticky silk for the steps of the web, and special silk for the cocoon.

Even the webs woven by spiders come in completely different shapes. The most common is a round web, but there are also square webs, flat and funnel- or dome-shaped. There are webs with covers so that prey does not escape from them; some spiders build a house in the form of a bell, located entirely under water.

The spider uses its web to build nets to catch prey, then the spider ties its thread around its victim just in case. Also, a spider can jump or descend without fear using its thread, and run along cobwebs as if on paths. Well, and not unimportantly, spiders weave cocoons for their eggs from the same silk thread in order to protect future offspring from unexpected situations that threaten their death.

In the jungles of Madagascar lives a spider that weaves a web that can stretch from one bank of a river or lake to the other, and the thread it uses consists of the strongest material of biological origin in the world. "Darwin's spider," discovered by Inga Agnarsson of the University of Puerto Rico, who first encountered similar webs in 2001 in Madagascar's Ranamofana National Park, is not particularly large, only 1.5 inches long (with its limbs straight), but a web that he weaves is huge. The length of the main thread can be up to 80 feet, and the circumference of the web is 9 feet square. The elasticity of the thread is twice that of any other spider, and given the fact that its tensile strength is higher than that of steel, the thread of this spider is the strongest naturally occurring material known to science.

Arachnids stand out from all insects by their ability to weave amazing web patterns.
How a spider weaves a web is impossible to imagine. The small creature creates large and strong networks. This amazing ability was formed 130 million years ago.

It is not by chance that all opportunities in animals appear and are consolidated through natural selection. Each action has a strictly defined purpose.

The spider weaves a web to achieve vital goals:

• catching prey;
• reproduction;
• strengthening their minks;
• fall insurance;
• deception of predators;
• facilitating movement on surfaces.

The spider order consists of 42 thousand species, each of which has its own preferences in the use of web construction. All representatives use the net to restrain the victim. Male aranemorphs leave seminal fluid on the net. Then the spider walks on the web, collecting secretions on the copulation organs.

After fertilization, the babies are formed in a protective arachnoid cocoon. Some females leave ferromones on the mesh - substances that attract partners. Orb weavers wrap threads around leaves and twigs. The result is dummies to distract predators. Silverfish living in water make houses with air cavities.

The size of the web depends on the type of spider. Some tropical arachnids create “masterpieces” with a diameter of 2 m, capable of holding even a bird. Conventional spider webs are smaller in size.
It is interesting to know how long a spider weaves a web. Zoologists managed to find out that the cross handler copes with the work in a few hours. Representatives of hot countries take several days to create large-area patterns. The main role in the process is played by special bodies.

The structure of the arachnoid glands

On the abdomen of the insect there are outgrowths - arachnoid warts with holes in the form of tubes.
Viscous fluid flows out through these ducts from the arachnoid gland. When exposed to air, the gel turns into thin fibers.

Chemical composition of the web

The unique ability of the released solution to harden is explained by its structural components.

The liquid contains a high concentration of protein containing the following amino acids:

• glycine;
• alanine;
• serine

The quaternary structure of the protein, when expelled from the duct, changes in such a way that filaments are formed as a result. From thread-like formations, fibers are subsequently obtained, the strength of which
4 – 10 times more durable than human hair.,
1.5 – 6 times stronger than steel alloys.

Now it becomes clear how a spider weaves a web between trees. Thin, strong fibers do not break, easily compress, stretch, rotate without twisting, and connect branches into a single network.

The purpose of a spider's life is to obtain protein food. The answer to the question “Why do spiders weave webs” is obvious. Primarily for hunting insects. They make a trapping net of complex design. The appearance of the patterned structures is different.

• Most often we see polygonal networks. Sometimes they are almost round. Weaving from spiders requires incredible skill and patience. Sitting on the top branch, they form a thread that hangs in the air. If you're lucky, the thread will quickly catch on a branch in a suitable place and the spider will move to a new point for further work. If the thread does not catch in any way, the spider pulls it towards itself, eats it so that the product does not disappear, and begins the process again. Gradually forming a frame, the insect begins to create radial bases. When they are ready, all that remains is to make connecting threads between the radii;
• Funnel representatives have a different approach. They make a funnel and hide at the bottom. When the victim approaches, the spider jumps out and pulls it into the funnel;
• Some individuals form a network of zigzag threads. The likelihood that the victim will not get out of such a pattern is much greater;
• The spider called “bola” does not bother itself; it weaves only one thread, which has a drop of glue at the end. The hunter shoots a thread at the victim, gluing it tightly;
• Spider-ogres turned out to be even more cunning. They make a small net between their paws, then throw it over the desired object.

Designs depend on the living conditions of insects and their species.

Conclusion

Having found out how a spider weaves a web, what its features are, all that remains is to admire this creation of nature and try to create something similar. Craftswomen copy patterns in the delicate patterns of knitted shawls. Antennas and nets for catching fish and animals are made using similar schemes. Humans have not yet been able to fully simulate the process.

Video: Spider weaves a web

Spiders belong to the oldest inhabitants of the Earth: traces of the first arachnids were found in rocks that are 340–450 million years old. Spiders are about 200–300 million years older than dinosaurs and more than 400 million years older than the first mammals. Nature has had enough time to not only increase the number of spider species (about 60 thousand are known), but also to equip many of these eight-legged predators with an amazing means of hunting - a web. The pattern of the web can be different not only among different species, but also among one spider in the presence of certain chemicals, such as explosives or narcotics. Spiders were even going to be launched into space to study the effect of microgravity on the web pattern. However, the substance that makes up the web hid the most mysteries.

The web, like our hair, animal fur, and silkworm threads, consists mainly of proteins. But the polypeptide chains in each spider thread are intertwined in such an unusual way that they have acquired almost record strength. A single thread produced by a spider is as strong as a steel wire of equal diameter. A rope woven from a web, only about the thickness of a pencil, could hold a bulldozer, a tank, and even such a powerful airbus as a Boeing 747 in place. But the density of steel is six times greater than that of spider webs.

It is known how high the strength of silk threads is. A classic example is an observation made by an Arizona doctor back in 1881. In front of this doctor, a shootout took place in which one of the shooters was killed. Two bullets hit the chest and went right through. At the same time, pieces of a silk handkerchief stuck out from the back of each wound. The bullets passed through clothing, muscles and bones, but were unable to tear the silk that got in their way.

Why is it that steel structures are used in technology, and not lighter and more elastic ones - made of material similar to spider webs? Why aren't silk parachutes replaced with the same material? The answer is simple: try to make the kind of material that spiders easily produce every day - it won’t work!

Scientists from around the world have long studied the chemical composition of the web of eight-legged weavers, and today the picture of its structure has been revealed more or less fully. The web strand has an inner core of a protein called fibroin, and surrounding this core are concentric layers of glycoprotein nanofibers. Fibroin makes up approximately 2/3 of the mass of the web (as well as, by the way, natural silk fiber). It is a viscous, syrupy liquid that polymerizes and hardens in air.

Glycoprotein fibers, the diameter of which can be only a few nanometers, can be located parallel to the axis of the fibroin thread or form spirals around the thread. Glycoproteins - complex proteins that contain carbohydrates and have a molecular weight from 15,000 to 1,000,000 amu - are present not only in spiders, but also in all tissues of animals, plants and microorganisms (some proteins in blood plasma, muscle tissues, cell membranes, etc.).

During the formation of a web, glycoprotein fibers are connected to each other due to hydrogen bonds, as well as bonds between CO and NH groups, and a significant proportion of bonds are formed in the arachnoid glands of arachnids. Glycoprotein molecules can form liquid crystals with rod-shaped fragments that stack parallel to each other, giving the structure the strength of a solid while maintaining the ability to flow like a liquid.

The main components of the web are the simplest amino acids: glycine H 2 NCH 2 COOH and alanine CH 3 CHNH 2 COOH. The web also contains inorganic substances - potassium hydrogen phosphate and potassium nitrate. Their functions are reduced to protecting the web from fungi and bacteria and, probably, creating conditions for the formation of the thread itself in the glands.

A distinctive feature of the web is its environmental friendliness. It consists of substances that are easily absorbed by the natural environment and does not harm this environment. In this regard, the web has no analogues created by human hands.

A spider can produce up to seven threads of different structure and properties: some for catching “nets”, others for its own movement, others for signaling, etc. Almost all of these threads could find wide application in industry and everyday life, if It would be possible to establish their widespread production. However, it is hardly possible to “tame” spiders, like silkworms, or to organize unique spider farms: the aggressive habits of spiders and the individual-farming traits in their character are unlikely to allow this to be done. And to produce just 1 m of web fabric, the “work” of more than 400 spiders is required.

Is it possible to reproduce the chemical processes that take place in the body of spiders and copy natural material? Scientists and engineers have long ago developed the technology of Kevlar - aramid fiber:

produced on an industrial scale and approaching the properties of spider webs. Kevlar fibers are five times weaker than spider webs, but are still so strong that they are used to make lightweight bulletproof vests, hard hats, gloves, ropes, etc. But Kevlar is produced in hot sulfuric acid solutions, while spiders require regular temperature. Chemists do not yet know how to approach such conditions.

However, biochemists have come closer to solving the materials science problem. First, spider genes were identified and deciphered, programming the formation of threads of one or another structure. Today this applies to 14 species of spiders. Then American specialists from several research centers (each group independently) introduced these genes into bacteria, trying to obtain the necessary proteins in solution.

Scientists at the Canadian biotechnology company Nexia introduced such genes into mice, then switched to goats, and the goats began to produce milk with the same protein that forms the thread of the web. In the summer of 1999, two African pygmy bucks, Peter and Webster, were genetically programmed to produce goats whose milk contained this protein. This breed is good because the offspring become adults at the age of three months. The company is still silent on how to make threads from milk, but has already registered the name of the new material it created - “BioSteel”. An article on the properties of “biosteel” was published in the journal “Science” (“Science”, 2002, vol. 295, p. 427).

German specialists from Gatersleben took a different path: they introduced spider-like genes into plants - potatoes and tobacco. They managed to obtain up to 2% soluble proteins in potato tubers and tobacco leaves, consisting mainly of spidroin (the main fibroin of spiders). It is expected that when the quantities of spidroin produced become significant, it will first be used to make medical bandages.

Milk obtained from genetically modified goats can hardly be distinguished by taste from natural milk. Genetically modified potatoes are similar to regular ones: in principle, they can also be boiled and fried.

Representatives of the arachnid order can be found everywhere. These are predators that hunt insects. They catch their prey using a web. This is a flexible and durable fiber to which flies, bees, and mosquitoes stick. How a spider weaves a web is a question often asked when looking at an amazing catching net.

What is a web?

Spiders are one of the oldest inhabitants of the planet; due to their small size and specific appearance, they are mistakenly considered insects. In fact, these are representatives of the order of arthropods. The spider's body has eight legs and two sections:

• cephalothorax;
• abdomen.

Unlike insects, they do not have antennae and a neck separating the head from the chest. The abdomen of an arachnid is a kind of factory for the production of cobwebs. It contains glands that produce a secretion consisting of protein enriched with alanine, which gives strength, and glycine, which is responsible for elasticity. According to the chemical formula, cobwebs are close to insect silk. Inside the glands, the secretion is in a liquid state, but when exposed to air it hardens.

Information. The silk of silkworm caterpillars and spider webs have a similar composition - 50% is fibroin protein. Scientists have found that spider thread is much stronger than caterpillar secretion. This is due to the peculiarity of fiber formation

Where does a spider's web come from?

On the abdomen of the arthropod there are outgrowths - arachnoid warts. In their upper part, the channels of the arachnoid glands open, forming threads. There are 6 types of glands that produce silk for different purposes (moving, lowering, entangling prey, storing eggs). In one species, all these organs do not occur at the same time; usually an individual has 1-4 pairs of glands.

On the surface of warts there are up to 500 spinning tubes that supply protein secretion. The spider spins its web as follows:

• spider warts are pressed against the base (tree, grass, wall, etc.);
• a small amount of protein adheres to the selected location;
• the spider moves away, pulling the thread with its hind legs;
• for the main work, long and flexible front legs are used, with their help a frame is created from dry threads;
• The final stage of making the network is the formation of sticky spirals.

Thanks to the observations of scientists, it became known where the spider’s web comes from. It is produced by movable paired warts on the abdomen.

Interesting fact. The web is very light; the weight of a thread wrapping the Earth along the equator would be only 450 g.

How to build a fishing net

The wind is the spider's best assistant in construction. Having taken out a thin thread from the warts, the arachnid exposes it to an air flow, which carries the frozen silk over a considerable distance. This is the secret way a spider weaves a web between trees. The web easily clings to tree branches, using it as a rope, the arachnid moves from place to place.

A certain pattern can be traced in the structure of the web. Its basis is a frame of strong and thick threads arranged in the form of rays diverging from one point. Starting from the outer part, the spider creates circles, gradually moving towards the center. It is amazing that without any equipment it maintains the same distance between each circle. This part of the fibers is sticky and is where insects will get stuck.

Interesting fact. The spider eats its own web. Scientists offer two explanations for this fact - in this way, the loss of protein during the repair of the fishing net is replenished, or the spider simply drinks water hanging on the silk threads.

The complexity of the web pattern depends on the type of arachnid. Lower arthropods build simple networks, while higher ones build complex geometric patterns. It is estimated that it builds a trap of 39 radii and 39 spirals. In addition to smooth radial threads, auxiliary and catcher spirals, there are signal threads. These elements capture and transmit to the predator the vibrations of the caught prey. If a foreign object (a branch, a leaf) comes across, the little owner separates it and throws it away, then restores the net.

Large arboreal arachnids pull traps with a diameter of up to 1 m. Not only insects, but also small birds fall into them.

How long does it take a spider to weave a web?

A predator spends from half an hour to 2-3 hours to create an openwork trap for insects. Its operating time depends on weather conditions and the planned size of the network. Some species weave silk threads daily, doing it in the morning or evening, depending on their lifestyle. One of the factors determining how long it takes a spider to weave a web is its type – flat or voluminous. The flat one is the familiar version of radial threads and spirals, and the volumetric one is a trap made from a lump of fibers.

Purpose of the web

Fine nets are not only insect traps. The role of the web in the life of arachnids is much broader.

Catching prey

All spiders are predators, killing their prey with poison. Moreover, some individuals have a fragile constitution and can themselves become victims of insects, for example, wasps. To hunt, they need shelter and a trap. Sticky fibers perform this function. They entangle the prey caught in the net in a cocoon of threads and leave it until the injected enzyme brings it into a liquid state.

Arachnid silk fibers are thinner than human hair, but their specific tensile strength is comparable to steel wire.

Reproduction

During the mating period, males attach their own threads to the female's web. By striking the silk fibers rhythmically, they communicate their intentions to a potential partner. The female receiving courtship descends onto the male’s territory to mate. In some species, the female initiates the search for a partner. She secretes a thread with pheromones, thanks to which the spider finds her.

Home for posterity

Cocoons for eggs are woven from the silky web secretion. Their number, depending on the type of arthropod, is 2-1000 pieces. The females hang the web sacs with eggs in a safe place. The cocoon shell is quite strong; it consists of several layers and is impregnated with liquid secretion.

In their burrow, arachnids weave webs around the walls. This helps create a favorable microclimate and serves as protection from bad weather and natural enemies.

Moving

One of the answers to why a spider weaves a web is that it uses threads as a vehicle. To move between trees and bushes, quickly understand and fall, it needs strong fibers. To fly over long distances, spiders climb to elevated heights, release a quickly hardening web, and then with a gust of wind they fly away for several kilometers. Most often, trips are made on warm, clear days of Indian summer.

Why doesn't the spider stick to its web?

To avoid falling into its own trap, the spider makes several dry threads for movement. I know my way around the intricacies of nets perfectly, and he safely approaches the stuck prey. Usually, a safe area remains in the center of the fishing net, where the predator waits for prey.

Scientists' interest in the interaction of arachnids with their hunting traps began more than 100 years ago. Initially, it was suggested that there was a special lubricant on their paws that prevented sticking. No confirmation of the theory was ever found. Filming with a special camera the movement of the spider's legs along fibers from the frozen secretion provided an explanation for the mechanism of contact.

A spider does not stick to its web for three reasons:

• many elastic hairs on its legs reduce the area of ​​contact with the sticky spiral;
• the tips of the spider's legs are covered with an oily liquid;
• movement occurs in a special way.

What is the secret of the structure of the legs that helps arachnids avoid sticking? On each leg of the spider there are two supporting claws with which it clings to the surface, and one flexible claw. As it moves, it presses the threads against the flexible hairs on the foot. When the spider raises its leg, the claw straightens and the hairs push away the web.

Another explanation is the lack of direct contact between the arachnid's leg and the sticky droplets. They fall on the hairs of the foot, and then easily flow back onto the thread. Whatever theories zoologists consider, the fact remains unchanged that spiders do not become prisoners of their own sticky traps.

Other arachnids, such as mites and pseudoscorpions, can also weave webs. But their networks cannot be compared in strength and skillful weaving with the works of real masters - spiders. Modern science is not yet able to reproduce the web using a synthetic method. The technology for making spider silk remains one of the mysteries of nature.