Cobwebs are secretions from the arachnoid glands, which harden after a short time. The chemical composition is similar to insect silk and consists of 50% protein. Most groups of arachnids are capable of secreting and weaving webs (false scorpions, spiders, some types of mites). People encounter it all the time, but few people think about its features and how it appears.
- Where does a spider's web come from? The secret of the arachnoid glands
- Web in one hour
- Hunting for prey
Stretching technology
To be effective, a fishing net must be stretched between something - for example, between branches. When the first thread has been made long enough by its creator, he stops spinning and spreads out the spinning organs. So he catches the breeze. The slightest movement of the wind (even from the heated ground) carries the web to the neighboring “support”, to which it clings. The spider moves along the “bridge” (most often with its back down) and begins weaving a new radial thread. Only when the base is secured does it begin to move around the circle, weaving sticky transverse lines into it. It must be said that spiders are very economical creatures. They eat damaged or old cobwebs that turn out to be unnecessary, putting “recyclables” into a second round of use. And, according to the creator, it becomes old quite quickly, since the spider often weaves a web every day (or night, if it is a shadowhunter).
Poisonous spiders
It's common to be afraid of spiders. Indeed, almost all of them are armed with poisonous claws, but only a few species are dangerous to humans. In the USA, you need to beware of two of them - the “brown recluse” ( Loxosceles reclusa
) and "black widow" ( Latrodectus mactans
). The length of the first is only 0.6 cm. This spider lives in the Midwest, often in homes where it hides behind furniture. At the site of its painful bite, an ulcer forms, which may never completely heal. The black widow spider is found throughout most of the United States. The bite of this species causes severe pain and can lead to death due to the neurotoxin injected into the wound. The female's body is shiny black with bright red spots. There is usually a red hourglass pattern on the underside of the abdomen. The male is much smaller than the female, but similar in coloring. The name “black widow” is explained by the fact that the female often eats her partner after mating, which, however, is a fairly common phenomenon among spiders. This species is not aggressive, and spiders usually try to hide from humans, but if picked up, they often bite.
Hunting
The goliath tarantula is a carnivorous spider. Before attacking a potential victim, this creature hides in an impromptu ambush. This is how the spider lies in wait for its “dinner”. As soon as the future prey approaches a distance sufficient for an attack, the tarantula pounces on it, using its fangs.
Contrary to its name, the tarantula does not feed on birds at all. This was apparently an isolated incident. The fact is that this type of spider from the order of arachnids was first noticed precisely when, for some reason, it was eating a bird. Zoologists who have been observing goliaths for a long time have come to the conclusion that the favorite and main food of these creatures are both invertebrates (butterflies, beetles) and vertebrates (mice, small snakes, frogs).
Where is it formed and where does it come from?
Spiders and their webs are a unique natural phenomenon in their own way. The weaving process is reminiscent of the production of cotton candy - a pre-mixed composition is pulled out of a narrow opening in the tank and hardens in air in the form of a thin thread.
The container is the animal’s abdomen, and the material is the secretion produced by its internal arachnoid glands.
In the lower part of the spider’s body (opistome) there are from 1 to 4 pairs of growths - arachnoid warts. In some species, these outgrowths are mobile and simultaneously serve as an organ of touch. This is the area where the spider produces its web.
Part of the surface of warts is dotted with small hairs - arachnoid tubes. Each of them is the exit duct of the internal gland and consists of two parts - thick (basal, internal) and thin (formative, terminal). The area with the tubes is called the arachnoid field.
Along with the tubes, chitinous cones, also located on the surface of the warts, participate in the production of the web. Larger glands open in them.
The release of the thread is controlled by the spider's central nervous system. Thickness, stickiness and even shade may vary.
To achieve this, various types of glands are involved in the weaving process, for example:
- tube-shaped - produce threads for the egg cocoon. Males do not have this type of gland;
- ampoule-shaped - produce dry thick threads for the base of the network;
- pear-shaped - strong thin fibers for attaching the web to the base;
- lobular - double silk fiber, the basis of the spiral threads of the fishing net;
- tree-like - they secrete glue to cover the base, which does not harden when in contact with air. With high magnification, droplets will be visible on the threads - the sticky secretion of the arborescent glands. It is on them that moisture concentrates during rain.
Each variety of spider has its own set of glands. Switching from one to the other takes about a minute. The cross spider weaves a web using 6 glands. Its arachnoid warts have from 480 to 560 tubes and about 20 cones.
Why don't they stick on their own?
In order to calmly move around the trap and not become its victim, the spider stretches dry threads, without an adhesive substance. He navigates the structure, so he knows which part of the fiber is intended for extraction and which is safe for him. He waits for the victim in the center of the building.
Additional factors that help the spider not stick to its own web:
- the tips of the predator's paws are lubricated with an oily liquid;
- there are many hairs on its limbs that reduce the area of contact with the sticky threads;
- it moves in a special way.
Modern scientists have not yet learned how to create a web artificially. But attempts to make an exact copy of it continue. Geneticists from Canada have artificially bred goats whose milk contains spider protein. Just like a spider makes a web, the technology of weaving it is a mystery of nature that the greatest minds have not solved.
Nature took care of the existence of spiders and gave them the ability to skillfully weave webs. It helps them obtain food, protect their offspring and their home, and also use it for transportation purposes. The openwork trap is attracting worldwide interest due to its mystery and the impossibility of artificial reproduction. Each type of arachnid arouses the deepest interest and amazes with its specific features.
The abdomen of spiders contains numerous arachnoid glands. Their ducts open into tiny spinning tubes, which are located at the ends of six arachnoid warts on the spider's abdomen. The cross spider, for example, has about 500-550 such tubes. The arachnoid glands produce a liquid, viscous secretion consisting of protein. This secret has the ability to instantly harden in air. Therefore, when the protein secretion of the arachnoid glands is secreted through the spinning tubes, it hardens in the form of thin threads.
121. Cross spider (with an open abdominal cavity) 2. Spider arachnoid warts
The spider begins to spin its web like this: it presses the web warts to the substrate; at the same time, a small portion of the released secretion, solidifies, sticks to it. The spider then continues to pull out the viscous secretion from the web tubes using its hind legs. When it moves away from the attachment site, the rest of the secretion simply stretches into quickly hardening threads.
Spiders use webs for a variety of purposes. In the web shelter, the spider finds a favorable microclimate, where it also takes refuge from enemies and bad weather. Some spiders weave webs around the walls of their burrows. The spider weaves sticky trapping nets from its web to capture prey. Egg cocoons, in which eggs and young spiders develop, are also made from cobwebs. The web is also used by spiders for travel - small Tarzans use it to weave safety threads that protect them from falling when jumping. Depending on the purpose of use, the spider can secrete sticky or dry thread of a certain thickness.
In terms of chemical composition and physical properties, cobwebs are close to the silk of silkworms and caterpillars, only it is much stronger and more elastic: if the breaking load for caterpillar silk is 33-43 kg per 1 mm 2, then for cobwebs it is from 40 to 261 kg per mm 2 (depending on the type)!
Other arachnids, such as spider mites and pseudoscorpions, can also produce webs. However, it was spiders who achieved true mastery in weaving webs.
After all, it is important not only to be able to make a web, but also to produce it in large quantities. In addition, the “loom” should be located in a place where it is more convenient to use
In pseudoscorpions and spider mites, the raw material base of the web is located... in the head, and the weaving apparatus is located on the oral appendages. In conditions of the struggle for existence, animals whose heads are weighed down with brains, and not with cobwebs, gain an advantage. That's what spiders are. The spider's abdomen is a real web factory, and the spinning devices - arachnoid warts - are formed from atrophied abdominal legs on the underside of the abdomen. And the spiders’ limbs are simply “golden” - they spin so deftly that any lacemaker would envy them.
Indian summer is a great time of autumn, when you can soak up the last warm rays of the sun of the year, enjoy excellent weather, and see the past summer. But, as usual, something must spoil the barrel of honey. Web. She's everywhere. She poisons my happiness, scares me and ruins my mood. She's annoying! The web rushes towards me in the most unexpected places, even where someone passed in front of me a minute ago, even where there is no vegetation nearby.
They also say that spider web is an incredibly strong and durable material. How does a spider weave a web, what spreads it everywhere?
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 secretion of the 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.
Unique qualities of spider “textiles”
Despite the small size of the creators, the features of the web cause some envy on the part of the crown of nature - man. Some of its parameters are incredible even with the achievements of modern science.
- Strength. The web can break from its own weight only if the spider weaves it 50 meters long.
- Exceptional subtlety. An individual web is noticeable only when caught in a beam of light.
- Elasticity and resilience. The thread stretches 2-4 times without breaking, and without loss of strength.
And all these qualities are achieved without any technical equipment - the spider makes do with what nature has provided it with.
How is a web weaved?
The basis of each spider trap is 3-4 load-bearing threads. This is the strongest part of the web. Radial threads are attached to the base, each end of which is attached to a support in the form of a tree branch, plant leaves, and so on. The spider applies a trapping spiral to the radial threads, which is the stickiest part of the trap. It is precisely this that spiders fall prey to—to prevent the prey from freeing itself, the predator quickly runs to it and injects poison. These substances transform the insides of insects caught in the web into a nutrient mass, which the spiders simply absorb into themselves.
The structure of the web
Construction stages
The base of the web is very similar to a snowflake or a point, from the center of which several rays radiate. These central threads-rays are the densest and thickest in their structure. Sometimes the spider makes a warp from several threads at once, as if strengthening its paths in advance.
When the base is ready, the animal proceeds to the construction of “catching spirals”. They are made from a completely different type of web. This liquid is sticky and sticks well. It is from the sticky web that the circles on the base are built.
The spider begins its construction from the outer circle, gradually moving towards the center. He amazingly senses the distance between the circles. Having absolutely no compass or special measuring instruments at hand, the spider accurately distributes the web so that there is an exclusively equal distance between the circles.
Web weaving technology
As a rule, many species of spiders prefer to be nocturnal, so they weave webs mainly at night. On average, a spider spends about an hour on this procedure. If you need to repair an insect trap, it takes even less time.
Below you can see in the video how a spider weaves a web and how much time it takes him to do it. If the web is torn off, then the next morning exactly the same web will appear in the same place. The most beautiful webs are produced by orb weavers. Using strong threads, the spider forms a triangle, after which it fills it with cells of a certain size.
Interesting to know! In the tropical forests of Brazil lives a tarantula spider that weaves such a strong web that local fishermen use it as nets to catch fish. From spider threads you can weave not only a thin, but also a fairly strong fabric. Some companies make body armor from spider substances.
In the garden you can see how the spider weaves a web, placing it on 2 trees. This could be an openwork fishing net or a funnel that glitters in the sun, attracting insects. Of course, for many this process is a mystery. It is even difficult to imagine how the spider was able to stretch its web between two trees. As a rule, a spider flies on a web from one tree to another under the influence of the wind. Having secured the second end, the simplest thing he can do is fill the space with cells.
At the same time, while in a state of flight, the spider controls the distance to the neighboring tree, while adjusting the length of the web. Sometimes, in order to catch on to a branch, he simply shoots a web at the right place.
The spider weaves a web. Watch this video on YouTube
Composition of the web
The basis of the web (2/3 of its composition) is the water-insoluble protein fibroin (fibrillar protein). This is a substance that gives spider webs increased strength. It consists of a complex of simple proteins (albumin), d-alanine (amino acid), glutamic and aminoacetic acids.
The stickiness of the web is provided by sericin (a substance of protein origin, silk glue). The chemical composition of the web also includes potassium nitrate and hydrogen phosphate, which provide protection against bacteria and fungi.
Depending on the type of glands used, the spider produces about 7 types of fibers of different chemical compositions, from which it weaves the structural parts of the web.
The structure of the thread is heterogeneous. It is composed of rigid protein crystals firmly connected by elastic ligaments.
The thread retains tensile strength and does not twist even with prolonged rotation. The last property is called “hinge”. Sunlight, hot and dry air weaken the strength of the thread.
Types of cobwebs
It is interesting not only how the spider weaves a web, but also the fact that it manages to produce different “varieties” of it. Roughly speaking, they can be divided into three types:
- Strong - produced only by netters and form the basis of fishing nets.
- Sticky. Jumpers are made from them, all in the same networks, and are glued at the slightest touch, and in such a way that it is very difficult to remove them.
- Household. Spiders use them to create cocoons and “doors” for burrows. Moreover, they also come in several types, since they are produced in varying degrees of softness and fluffiness.
Scientists have identified another type of web that reflects ultraviolet light, luring butterflies. Many people believe that a finished web necessarily has its own pattern. However, this is not so: the names of spiders capable of creative delights can be counted without much difficulty, and all such artists belong to the araneomorphic representatives of this order of arthropods.
Why does a spider need a web?
The spider doesn't just spin its web where it wants and when it wants. He weaves it as needed and in places where it may be useful to him. Each web has its own purpose. Females spin webs to attract males. That's because:
- The spider's glands are located near the genitals, which allows the female to simultaneously secrete a special secret that attracts males.
- Captivating networks weave a web of spheres. Such networks can have a diameter of 2 m or more. The strength of the threads is such that a bird, but not a large rodent or amphibian, can become entangled in the net. Most spiders catch insects and their larvae.
- Spiders living in the ground dig holes with many passages. They do not weave a trap, but cover the entrance with a web and weave signal threads. These wires give a signal if the victim is near the hole. In this case, the spider immediately reacts and appears at the entrance to its hole.
- Spiders lead a closed life and form pairs only during the breeding season. Each spider protects its territory and does not allow strangers to it. When exploring new territories, the spider weaves a long thread, attaching it to any base, and waits for a good gust of wind. Once in the air, the spider, under the influence of the wind, is able to travel tens and even hundreds of kilometers. Such migrations spread with the birth of young spiders.
- After mating, the female creates a special cocoon from the net and lays up to 1000 pieces of eggs in it. Some species attack the cocoon somewhere, and some drag it until the spiders are born.
- Some species of spiders, such as the water spider, use strands of web to build a nest underwater. This house is filled with air and a female lives in it. During the mating season, she releases a spider to her, after which offspring are born, which live in this nest for some time. This is where he drags the captured victim.
- Once in the insect's web, the spider wraps it in the web, after injecting the toxin. After this, he turns away from his victim and watches her. After complete death, start eating. If the spider is not hungry, leave another victim until it becomes hungry.
- There are varieties that wrap the leaves with cobwebs, after which they stretch a long web. If necessary, the spider stretches the web, thereby reviving the leaf. As a result, some predators respond to this leaf rather than the actual spider's nest.
There are also skillful spiders that build a raft from improvised materials and webs and swim on it, hunting for fry, larvae, crustaceans, and so on.
If the fishing net is severely damaged, the spider may leave it and begin to form somewhere near a new web.
Important point! Some arthropods eat nets. Experts explain such actions of spiders by the fact that their body requires replenishment of protein reserves. In addition, moisture always accumulates on the web, which is necessary for the spider.
Why spider webs are five times stronger than steel: scientists have finally found the answer
Strong networks
The owner of the web is the formidable and extremely poisonous brown recluse spider. To find out why the web is five times stronger than steel, scientists studied the threads that the poisonous spider Loxosceles reclusa produces to create trapping nets and containers for clutches of eggs.
When bitten by this spider with incredibly long legs, a person develops loxoscelism - inflammation, and then gangrene scabs from dying tissue at the site of the bite. The researchers took a closer look at the web using an atomic microscope and discovered one surprising circumstance. What the naked eye perceives as a single thin thread (about 1000 times thinner than a human hair) is actually a dense “rope” woven from hundreds of nanofibers. The diameter of one such fiber is 20 millionths of a millimeter. Like modern cables, each strand of the web consists of parallel nanostructures at least 1 micron in length. Not a very long fiber, is it? So it may seem at first glance. However, if we look at the structure at the micro level, it turns out that the length of such fibers can be about 50 times greater than the width - and the researchers are confident that they can stretch even more.
Nanofibers in living nature: the secret of strength
The idea that spider webs are made of nanofibers is not new and has been discussed many times in the scientific community. However, until now, researchers have been unable to provide evidence that the nanoscopic filaments make up the entire web, rather than just parts of it. The scientists’ “secret weapon” in this case was the unique properties of the Loxosceles reclusa web. While most spiders spin cylindrical threads, these webs are actually flat, like a ribbon—this made it easier to study under a powerful microscope.
The new discovery builds on even earlier work that the team published a year ago. Then scientists discovered that L. reclusa (also called “brown recluse spiders”) reinforced flat threads using a special weaving technique. Like a living sewing machine, the spider weaves approximately 20 microloops into every millimeter of its web. Such “stitches” strengthen the sticky fishing net and give it incredible strength. The researchers say that even if the shape of the threads and the weaving techniques of other spiders differ, the new discovery could be a starting point for studying the natural fibers that other species produce.
Conclusion
For humanity, this information is extremely important - knowing how nature creates super-strong and very light threads, we ourselves will be able to create their synthetic analogues. Artificial web would be useful everywhere, from the military and medical industries to ordinary textiles. However, it is now extremely difficult to recreate such a fiber on an industrial scale, and no one has succeeded in this (although there were such attempts a couple of years ago). Scientists hope that further research will sooner or later put one of the most complex and unusual materials in the world at the service of humanity.
The web is needed for insurance
Jumping spiders use web threads to attack. They attach a safety thread to an object and jump onto the intended victim. The South Russian tarantula, leaving its hole, pulls behind it a barely noticeable cobweb thread, along which it will always find the entrance to the abandoned shelter. If the insurance breaks, the tarantula is unable to find its hole and goes in search of a new one. Jumping spiders spend the night on web threads attached to the substrate. This is a kind of insurance against predators.
The main task of the web is to catch prey.
