Web description. How does a spider weave a web? Where is the web formed and how is it used by the spider? Particularly dangerous individuals

Candidate of Physical and Mathematical Sciences E. Lozovskaya

Science and life // Illustrations

The adhesive substance covering the thread of the catching spiral is evenly distributed throughout the web in the form of bead droplets. The picture shows the place where two fragments of the catcher spiral are attached to the radius.

Science and life // Illustrations

Science and life // Illustrations

Science and life // Illustrations

Science and life // Illustrations

Initial stages construction catcher net cross spider.

The logarithmic spiral approximately describes the shape of the auxiliary spiral thread that the spider lays when constructing a wheel-shaped catching net.

The Archimedes spiral describes the shape of the adhesive trapping thread.

Zigzag threads are one of the features of the webs of spiders of the genus Argiope.

The crystalline regions of the silk fiber have a folded structure similar to the one shown in the figure. The individual chains are connected by hydrogen bonds.

Young cross spiders that have just emerged from their web cocoon.

Spiders of the family Dinopidae spinosa weave a web between their legs and then throw it over their prey.

The cross spider (Araneus diadematus) is known for its ability to weave large, wheel-shaped trapping webs.

Some types of spiders also attach a long “ladder” to the round trap, which significantly increases the efficiency of hunting.

Science and life // Illustrations

This is what the spider tubes from which the threads of spider silk emerge look like under a microscope.

Spiders may not be the most attractive creatures, but their creation, the web, is nothing short of awe-inspiring. Remember how the geometric regularity of the finest threads shimmering in the sun, stretched between the branches of a bush or among tall grass, captivates the eye.

Spiders are one of the oldest inhabitants of our planet, having settled on land more than 200 million years ago. There are about 35 thousand species of spiders in nature. These eight-legged creatures, which live everywhere, are recognizable always and everywhere, despite differences in color and size. But the most important thing is distinctive feature- is the ability to produce spider silk, a natural fiber unsurpassed in strength.

Spiders use webs for a variety of purposes. They make cocoons for eggs from it, build shelters for wintering, use it as a “safety rope” when jumping, weave intricate trapping nets and wrap up caught prey. A female ready for mating produces a web thread marked with pheromones, thanks to which the male, moving along the thread, easily finds a partner. Young spiders of some species fly away from the parental nest on long threads carried by the wind.

Spiders feed mainly on insects. The hunting devices they use to get food are of the most different forms and types. Some spiders simply stretch out several signal threads near their shelter and, as soon as an insect touches the thread, they rush at it from ambush. Others throw a thread with a sticky drop at the end forward, like a kind of lasso. But the pinnacle of the design activity of spiders is still round wheel-shaped nets, located horizontally or vertically.

To build a wheel-shaped catching net, the cross spider, a common inhabitant of our forests and gardens, produces a fairly long, strong thread. A breeze or rising air flow lifts the thread upward, and, if the place for building the web is chosen well, it clings to the nearest branch or other support. The spider crawls along it to secure the end, sometimes laying another thread for strength. Then he releases a freely hanging thread and attaches a third to its middle, so that a Y-shaped structure is obtained - the first three radii out of more than fifty. When the radial threads and frame are ready, the spider returns to the center and begins to lay out a temporary auxiliary spiral - something like "scaffolding". The auxiliary spiral holds the structure together and serves as a path for the spider when constructing a catching spiral. The entire main frame of the net, including the radii, is made of non-adhesive thread, but for the catcher spiral, a double thread coated with an adhesive substance is used.

What's surprising is that these two spirals have different geometric shapes. The temporary spiral has relatively few turns, and the distance between them increases with each turn. This happens because, when laying it, the spider moves at the same angle to the radii. The shape of the resulting broken line is close to the so-called logarithmic spiral.

The sticky trapping spiral is built according to a different principle. The spider starts at the edge and moves towards the center, keeping the same distance between the turns, creating an Archimedes spiral. At the same time, it bites off the threads of the auxiliary spiral.

Spider silk is produced by special glands located in the back of the spider's abdomen. At least seven types of arachnoid glands are known, producing different filaments, but none of them known species All seven types of spiders are not found at once. Usually a spider has from one to four pairs of these glands. Weaving a web is not a quick task, and it takes about half an hour to build a medium-sized trapping net. To switch to the production of a different type of web (for the catching spiral), the spider needs a minute's respite. Spiders often reuse webs by eating leftover webs that have been damaged by rain, wind, or insects. The web is digested in their body with the help of special enzymes.

The structure of spider silk has been perfectly developed over hundreds of millions of years of evolution. This natural material combines two wonderful properties - strength and elasticity. A web made of cobwebs can stop an insect flying towards full speed. The thread from which spiders weave the base of their hunting web is thinner than a human hair, and its specific (that is, calculated per unit mass) tensile strength is higher than that of steel. If you compare spider thread with steel wire of the same diameter, they will support approximately the same weight. But spider silk is six times lighter, which means six times stronger.

Like human hair, sheep wool and silk cocoons of silkworm caterpillars, the web consists mainly of proteins. In terms of amino acid composition, the spider web proteins - spidroins - are relatively close to fibroins, the proteins that make up the silk produced by silkworm caterpillars. Both contain unusually high amounts of the amino acids alanine (25%) and glycine (about 40%). Areas of protein molecules rich in alanine form crystalline regions densely packed into folds, providing high strength, and those areas where there is more glycine represent a more amorphous material that can stretch well and thereby impart elasticity to the thread.

How is such a thread formed? There is no complete and clear answer to this question yet. The process of web spinning has been studied in most detail using the example of the ampullaid gland of the orb-weaving spider Nephila clavipes. The ampullaid gland, which produces the strongest silk, consists of three main sections: a central sac, a very long curved canal, and a tube with an outlet. From the cells on the inner surface of the sac emerge small spherical droplets containing two types of spidroin protein molecules. This viscous solution flows into the tail of the sac, where other cells secrete a different type of protein - glycoproteins. Thanks to glycoproteins, the resulting fiber acquires a liquid crystalline structure. Liquid crystals are remarkable in that, on the one hand, they have a high degree of order, and on the other, they retain fluidity. As the thick mass moves towards the outlet, the long protein molecules are oriented and aligned parallel to each other in the direction of the axis of the forming fiber. In this case, intermolecular hydrogen bonds are formed between them.

Humanity has copied many of nature's design discoveries, but such a complex process as spinning a web has not yet been reproduced. Scientists are now trying to solve this difficult problem using biotechnological techniques. The first step was to isolate the genes responsible for the production of the proteins that make up the web. These genes were introduced into the cells of bacteria and yeast (see "Science and Life" No. 2, 2001). Canadian geneticists have gone even further - they have bred genetically modified goats whose milk contains dissolved spider web proteins. But the problem is not only in obtaining the spider silk protein, it is necessary to model natural process spinning. But scientists have yet to learn this lesson from nature.

The web is the very essence of the spider. Although other arthropods also produce webs, no more group, all of whose representatives could do this. Those that can still do it usually do it during strictly defined periods. life cycle, and the web itself is used for one or two purposes (for example, butterfly caterpillars build a cocoon). In contrast to them All spiders produce webs throughout all life, using it wherever possible. Tarantulas are no exception. They use the web for many purposes:

1. For lining the den. Moreover, many woody species(eg kind Avicularia) make nests in crevices in the bark entirely from cobwebs. In fact, these are air holes.

2. Terrestrial species They often use cobwebs to tightly weave the entrance to a hole when they do not want to be disturbed.

3. The web can become Ariadne's thread, along which a wandering spider can find its way to the hole.

4. Lumps of earth are covered with cobwebs, which the spider throws out of the hole as its home expands.

5. In captivity, many spiders weave a “tablecloth” when feeding. It is unknown whether their wild counterparts do anything similar.

6. A bedding mat for shedding is made from cobwebs.

7. The web becomes a temporary sperm store when the male is preparing to meet the female.

8. The male most often determines the presence of a female by chemical signals (one can hardly say “smell” here) on the web surrounding the entrance to the burrow.

9. Finally, the female weaves an egg cocoon from the web, a container for developing eggs.

What tarantulas do not use webs for is to make nets and traps, which many people do Araneomórhae, the so-called higher spiders. Although some species of tarantulas stretch signal threads radially at the entrance to the burrow, the vibration of which warns the spider of the approach of prey or a potential predator. Due to the fact that tarantulas do not weave nets and traps, they were considered more primitive. This argument seems unconvincing. These creatures have no less ability to weave webs than higher spiders. But since they are significantly heavier than higher spiders, even underground ones, making openwork structures for catching prey is simply impractical.

From a chemical point of view, spider web is almost entirely a protein product. Arachnoid glands produce web as needed, and it is released through microscopic holes in the arachnoid appendages. When released, it is stretched, which allows protein molecules to interact with each other, as a result of which the thread hardens and acquires fantastic strength. Please note that the hardening of the thread is not drying, since it can just as well harden under water (the European water spider is an example Argyroneta aquatica, sem. Argyronetidae).

The most surprising thing about the web is its amazing strength. Many peoples of the world even use it to make fishing nets (for small fish), as well as threads when several silks are twisted. Some types of web are stronger than steel wire of the same diameter. Its high tensile strength, combined with its microscopic thickness, made spider webs indispensable in the manufacture of sight crosshairs during World War II. Compared to nylon thread, it can withstand twice the stretch.

Finally, despite the fact that it is almost pure protein, spider webs break down extremely slowly. In nature, it can hang on a branch for many weeks after its creator has disappeared. It can remain in the house for an almost unlimited time until it is swept away by the broom of an indignant housewife. It will remain in the terrarium for a year or more, showing only minor signs of degradation. Bacteria and fungi grow very poorly on it and few organisms eat it, despite its obvious nutritional value. Why? Unknown.

The production of cobwebs involves the consumption of both protein and energy. If there was no way to process it, it would be costly for the spider. Most spiders eat at least some of the used silk structures. Although tarantulas do this much less frequently than most other spiders.

It is easy to decide that this proves the primitiveness of tarantulas, which have not yet developed the instinct for preserving valuable material to the same extent as more advanced spiders. But it seems no less convincing that the energy and protein consumption of tarantulas, which weave relatively little, is significantly less, especially compared to body weight. Accordingly, the need to save is not so great, and they can afford some extravagance.

Although tarantulas may eat the “tablecloth” that is sometimes woven when feeding in captivity, they usually do not eat other web structures. These latter should be removed from time to time.

It is unknown what happens to all the webs that tarantulas produce in nature. Buildings of many tropical species quite large and have considerable strength. However, it is not typical for tarantulas in the American Southwest a large number of there are cobwebs around the hole, and even less inside. Do they not weave enough webs? Or they eat most old? And if they eat, then why don’t they do this when kept in captivity? The mystery remains a mystery.

The web is a kind of secret produced by the arachnoid glands. Such a secretion, after a short time after release, is able to solidify in the form of strong protein threads. Cobwebs are produced not only by spiders, but also by some other representatives of the arachnid group, including pseudoscorpions and mites, as well as labiopods.

How spiders make webs

A large number of arachnoid glands are located in abdominal cavity spider. The ducts of such glands open into tiny spinning tubes that have access to the end part of special arachnoid warts. The number of spinning tubes may vary depending on the type of spider. For example, the very common cross spider has five hundred of them.

This is interesting! The arachnoid glands produce a liquid and viscous protein secretion, the peculiarity of which is the ability to almost instantly harden under the influence of air and turn into thin long threads.

The process of spinning a web involves pressing the spider warts onto a substrate. The first, insignificant part of the released secretion hardens and reliably sticks to the substrate, after which the spider pulls out the viscous secretion using its hind legs. In the process of removing the spider from the site of attachment of the web, the protein secretion stretches and quickly hardens. Today, seven different types of arachnoid glands that produce different types threads

Composition and properties of the web

Spider web is a protein compound that also contains glycine, alanine and serine. The inner part of the formed threads is represented by hard protein crystals, the size of which does not exceed several nanometers. The crystals are held together by highly elastic protein bonds.

This is interesting! An unusual property of the web is its internal articulation. When hung on a spider's web, any object can be rotated an unlimited number of times without twisting.

The primary threads are intertwined by the spider and become thicker spider fibers. The strength indicators of the web are close to those of nylon, but are much stronger than the secret silkworm. Depending on the purpose for which the web is intended to be used, the spider can produce not only sticky, but also dry thread, the thickness of which varies significantly.

Functions of the web and its purpose

Webs are used by spiders for a variety of purposes. A shelter woven from a strong and reliable web allows you to create the most favorable microclimatic conditions for arthropods, and also serves as a good shelter both from bad weather and from numerous natural enemies. Many arthropod arachnids are capable of weaving their web around the walls of their burrow or making it into a kind of door into their home.

This is interesting! Some species use webs as transport, and young spiders leave the parental nest on long web threads, which are picked up by the wind and transported over considerable distances.

Most often, spiders use webs to weave sticky trapping networks, which allows them to effectively catch prey and provide food to the arthropod. No less famous are the so-called egg cocoons made from webs, inside which young spiders appear. Some species weave web-like safety threads that protect arthropods from falling while jumping and for moving or catching prey.

Web for reproduction

The breeding season is characterized by the release of arachnoid threads by the female, which make it possible to find the optimal pair for mating. For example, male web-slingers are capable of constructing, next to the nets created by females, miniature mating web laces into which spiders are lured.

Male cross spiders deftly attach their horizontal webs to radially arranged strands of trapping webs made by females. By delivering strong blows to the web with their limbs, the males cause the web to vibrate and thus in an unusual way, invite females to mate.

Web for catching prey

In order to catch their prey, many species of spiders weave special trapping nets, but some species are characterized by the use of peculiar web lassos and threads. Spiders that hide in burrow dwellings place signal threads that stretch from the arthropod’s abdomen to the very entrance to its shelter. When prey falls into the trap, the vibration of the signal thread is instantly transmitted to the spider.

Sticky spiral trapping nets are built according to a slightly different principle. When creating it, the spider begins weaving from the edge and gradually moves towards the central part. In this case, the same gap between all turns is necessarily maintained, resulting in the so-called “Archimedes spiral”. The threads on the auxiliary spiral are specially bitten by the spider.

Web for insurance

Jumping spiders use web threads as insurance when attacking a victim. Spiders attach a safety thread of the web to any object, after which the arthropod jumps on the intended prey. The same thread, attached to the substrate, is used for overnight shelter and protects the arthropod from attacks by all kinds of natural enemies.

This is interesting! South Russian tarantulas, leaving their burrow home, pull behind them a very thin web thread, which allows them to quickly find if necessary way back or the entrance to the shelter.

Web as transport

By autumn, some species of spiders hatch their young. Young spiders that survive the process of growing up try to climb as high as possible, using trees, tall bushes, roofs of houses and other buildings, fences for this purpose. Having waited long enough strong wind, a small spider produces a thin and long web.

The distance of movement directly depends on the length of such a transport web. Having waited for a good tension of the web, the spider bites off its end and takes off very quickly. As a rule, “travelers” are able to fly several kilometers on a web.

Silver spiders use cobwebs as water transport. This spider requires breathing to hunt in bodies of water. atmospheric air. When descending to the bottom, the arthropod is able to capture a portion of air, and on aquatic plants a kind of air bell is constructed from the web, which holds air and allows the spider to hunt its prey.

How a spider weaves a web and what its features are, you will learn from this article.

What is a web?

The web is a protein mass secreted by the specific glands of the spider. This liquid substance, which, when exposed to air, very quickly turns into a polymer, forming sticky threads. By the way, spider web is considered a fairly durable material. Even steel is inferior in its stability. The strength of the web is amazing. What makes it so durable? It's all about the specific components - these are 2 proteins. One of the proteins is responsible for the strength of the web, and the second for elasticity. In the web, each thread is covered with an adhesive special substance, which should hold the prey as it enters the network. The victim, trying to get out of the trap, becomes even more entangled in the web and is finally absorbed by this substance.

The strongest webs are found in orb-weaving spiders, which have a large number of glands that “weave” strong threads.

How do spiders weave their threads?

Weaving a web is not the easiest process. It all depends on what type of web. Very often, the spider produces quite complex threads for weaving, which require the participation of different glands. In addition, the spider itself needs to actively work to produce such durable material.

Here's how it goes. First, the tip of the future adhesive thread needs to be hooked onto something (for example, a branch). But there must be three ends on which it is attached, so that in the end it turns out isosceles triangle. The spider attaches the opposite end to the surface on the corresponding side of the corner. After this, the formation of threads begins, which cross each other in the center from one attachment point to the opposite. After it begins new stage spider's work. A thread is woven to the edges from the center, connecting the previous threads to each other. The last thing to do is to create a special signal thread. Its task is to inform the spider that prey has been caught in its web. It is also worth noting the following: the spider itself in its network is located in the very center, filling the gaps in it.

Spider (Araneae) belongs to the phylum arthropod, class Arachnida, order Spiders. Their first representatives appeared on the planet approximately 400 million years ago.

Spider - description, characteristics and photographs

The body of arachnids consists of two parts:

• The cephalothorax is covered with a shell of chitin, with four pairs of long jointed legs. In addition to them, there is a pair of claws (pedipalps), used by mature individuals for mating, and a pair of short limbs with poisonous hooks - chelicerae. They are part oral apparatus. The number of eyes in spiders ranges from 2 to 8.
• Abdomen with breathing holes located on it and six arachnoid warts for weaving webs.

The size of spiders, depending on the species, ranges from 0.4 mm to 10 cm, and the span of their limbs can exceed 25 cm.

Coloring and pattern on individuals different types depend on the structural structure of the integument of scales and hairs, as well as the presence and localization of various pigments. Therefore, spiders can have either a dull solid color or bright color various shades.

Types of spiders, names and photographs

Scientists have described more than 42,000 species of spiders. About 2,900 varieties are known in the CIS countries. Let's consider several varieties:

• Blue-green tarantula (Chromatopelma cyaneopubescens)

one of the most spectacular and beautifully colored spiders. The tarantula's abdomen is red-orange, its limbs are bright blue, and its carapace is green. The size of the tarantula is 6-7 cm, with a leg span of up to 15 cm. The spider’s homeland is Venezuela, but this spider is found in Asian countries and in African continent. Despite belonging to tarantulas, this type does not bite spiders, but only marks special hairs located on the abdomen, and only in case of severe danger. The hairs are not dangerous for humans, but they cause minor burns on the skin, similar in effect to nettle burns. Surprisingly, female chromatopelma are long-lived compared to males: the lifespan of a female spider is 10-12 years, while males live only 2-3 years.

• Flower spider (Misumena vatia)

belongs to the family of side-walking spiders (Thomisidae). Color varies from absolutely white to bright lemon, pink or greenish. Male spiders are small, 4-5 mm long, females reach sizes of 1-1.2 cm. The species of flower spiders is distributed throughout European territory(excluding Iceland), found in the USA, Japan, and Alaska. The spider lives in open areas with an abundance of flowering herbs, as it feeds on the juices of those caught in its “embraces” and.

• Grammostola pulchra (Grammostola Pulchra)

Sidewalk spiders (crab spiders) spend most of their lives sitting on flowers waiting for prey, although some members of the family can be found on tree bark or forest floors.

Representatives of the family of funnel-web spiders place their webs on tall grass and branches of bushes.

Wolf spiders prefer damp, grassy meadows and swampy wooded areas, where they are found in abundance among fallen leaves.

The water (silver) spider builds a nest underwater, attaching it to various bottom objects with the help of webs. He fills his nest with oxygen and uses it as a diving bell.

What do spiders eat?

Spiders are quite original creatures that eat very interestingly. Some types of spiders may not eat for a long time - from a week to a month or even a year, but if they start, there will be little left. Interestingly, the weight of food that all spiders can eat during the year is several times greater than the weight of the entire population living on the planet today.
How and what do spiders eat? Depending on the species and size, spiders forage and eat differently. Some spiders weave webs, thereby organizing clever traps that are very difficult for insects to notice. Digestive juice is injected into the caught prey, corroding it from the inside. After some time, the “hunter” draws the resulting “cocktail” into his stomach. Other spiders “spit” sticky saliva while hunting, thereby attracting prey to themselves.

snail or earthworm and eat them there in peace.

The queen spider hunts only at night, creating a sticky web bait for unwary moths. Noticing an insect next to the bait, the queen spinner quickly swings the thread with her paws, thereby attracting the attention of the prey. The moth happily hovers around such a bait, and having touched it, it immediately remains hanging on it. As a result, the spider can calmly attract it to itself and enjoy its prey.

Large tropical tarantula spiders happily hunt small ones,

Haymaking spiders prefer cereal grains.

Judging by numerous notes by scientists, a huge number of spiders destroy small rodents and insects several times more than the animals living on the planet.