The cross spider, or Araneus, belongs to the orb-weaver family, a genus of araneomorphic spiders. In total, there are more than 1000 species of representatives of this genus in the world, but in Russia and the CIS countries you can find from 15 to 30 species. Crosses live mainly in damp and damp places - in fields, meadows, forests, along the banks of reservoirs and rivers.
Features of the cross spider
Spiders are dioecious animals. After mating, the male dies, and the female begins to weave a cocoon from the web for eggs, which she usually lays in the fall. The cocoon turns out to be quite dense; the female carries it on herself for some time, and then hides it in any safe place - in a crack in the bark of trees or behind a loose piece of bark. In spring, young (juvenile) spiders emerge from the cocoon. They become sexually mature by the end of summer, after which the female that gave birth to them dies.
In the first days of his life, the male cross spider also builds a web - he needs to eat something. But upon reaching maturity, he begins to wander in search of adventure and, of course, noticeably loses weight. During this period, he is driven by only one desire - to find the female’s web.
When the female's web is found, he makes every effort not to get to her for lunch. To do this, he weaves a thread for himself down from the edge of the web - for retreat. Then he carefully tugs the thread. The female immediately rushes in search of prey, and the male retreats down the rescue thread.
This is repeated several times until the female understands that it is not the prey who is pulling the web, but her long-awaited partner. Then she changes her anger to mercy, and the spiders mate. But the male must not let down his vigilance, because... after mating, the hunting instinct awakens in the female again. If he does not escape in time, he may well be eaten.
Between their fangs and legs, male spiders have a set of appendages called pedipalps, which they use as reproductive organs. Before mating, the male spider builds a web called a sperm web and deposits sperm from a gonopore that opens into the web. Then, through a process called sperm induction, the spider draws sperm into its pedipalps. It will use these sperm-filled pedipalps to place its sperm inside both of the female spider's genital openings, called the epiglottis, which are located just in front of her gonopore. Once completed, the sperm remains stored inside the female spider in specialized vessels. This sperm fertilizes the spider's eggs as they pass through the oviduct before being deposited through the gonopore into a silken egg sac, which can contain up to a thousand eggs.Of course, there's more to spider reproduction than just the bare-bones mechanics of sperm meeting eggs, and true to its creepy nature, spider sex is weird and a little terrifying. Most spiders engage in sexual cannibalism, where one spider, usually the female of the species, kills and eats another spider immediately after mating. Since female spiders can choose which sperm fertilizes their eggs, this violent act can increase the chances of reproductive success for the male spider, since the female spider may be too busy eating him to mate with another male. Some male spiders even choose to stick to kill food (of which they are the main course) to ensure their sperm is preserved.
Because spider mating is so dangerous, many species have evolved sophisticated ways to deal with spider sex in a sensitive manner. For example, some male spiders use mating dances or web or ground tapping to calm the female spider before mating. Other spider admirers offer the woman the gift of a tasty fly carefully wrapped in silk to distract her attention for mating; if the fly is unavailable, the sneaky male spider may even wrap the pebble instead.
Once mating occurs, some male spiders have developed techniques to improve their chances of reproductive success. In addition to allowing themselves to become food, some males tear off their pedipalps and leave them inside the female to act as a plug to prevent other spiders from mating with her. Other spiders use the secretion to seal the female spider's genital openings for the same reason.
Any description of creepy spider mating would be remiss to forget what happens after successful breeding. About one to four weeks after laying, the egg sac ruptures, releasing up to a thousand writhing spiderlings. Some spiders simply disperse on their running legs, while others use a single strand of silk to catch air currents and a balloon in the air. Still others, like the wolf spider, crawl onto the mother's back, so that she becomes a writhing collection of hundreds of tiny spiders that scatter in all directions if disturbed. Pleasant dreams!.
Reproduction of the cross spider
The cocoon, which the female weaves in autumn, contains from 300 to 800 amber-colored eggs. Under the protection of the cocoon, future spiderlings are not afraid of either cold or flood - it is very light and does not get wet. The eggs wait out the winter in the cocoon, and in the spring small spiders emerge from the eggs. For some time they sit inside the cocoon, afraid to leave such a cozy shelter. But gradually they spread out and begin to live on their own.
It is clear that it will be very difficult for such a huge offspring to get settled in life. Competition is very high, some will die of hunger, and others will be eaten by their relatives. Therefore, the young spiders face a serious task - to disperse as quickly as possible in order to increase their chances of survival.
Their legs are small and weak, so the spiders move, gliding with the help of their web, like real aeronauts. With a fair wind, a spider can fly a distance of 300-400 km. When the wind subsides, the web falls to the ground, the spider throws it away and begins to settle in a new place. If he is lucky with the site, he will be able to catch up to 500 insects per day with his nets. The hunt is ongoing.
According to naturalists, millions of spiders live in meadows, fields and forests, destroying entire legions of insects, including those dangerous to humans and their households. If it were not for spiders, the number of flies, mosquitoes, gnats, midges, moths and aphids would be several orders of magnitude greater and could seriously poison our lives. Experts do not even exclude the possibility of using spiders in biological pest control.
Reproduction and development of spiders
The males of most spiders are much smaller than the females. They do not build trapping nets, but actively scour everywhere, content with random prey, and most importantly, they look for females. Having found a female, the male approaches her very carefully, tapping the web with his tentacles, and when the female rushes towards him, he jumps back and approaches again. The male acts cautiously, because the female may mistake him for prey and... eat him. In addition to tapping with its claws, the male takes various poses - performs the so-called “spider dances”. These “dances” are different for different types of spiders, each species has its own. By them the female recognizes the male of her species. Finally, the male manages to approach the female and impregnate her. After this, he quickly runs away, and those who hesitate will die.
The male inserts a package with male reproductive cells (devoid of flagella) into the female's genital opening with his foot - he copulates.
Fertilization in spiders is internal.
After some time, the fertilized female lays eggs, enveloping them in a web, so that a cocoon is formed. Females of some species attach this cocoon to the walls or to the web in the shelter in which they live, others hide the cocoon in a secluded place, others carry it with them, holding it with their hind legs, and sometimes continue to carry even hatched spiders. Material from the site https://doklad-referat.ru
Young spiders continue to stick together at first, then disperse. In some species, dispersal of young occurs by air. To do this, the young spider climbs somewhere higher and produces a light and long (up to a meter or more) web. This web is picked up by the wind and the spider, holding on to it, flies wherever it needs to go. If the web soon encounters an obstacle, the young traveler again climbs higher and repeats his maneuver. This happens in the fall - and then everywhere (on bushes, grass and fences) we see cobwebs sparkling in the sun, left by settling spiders, and sometimes you can see the aeronaut himself flying on a cobweb.
Spiders hibernate by climbing somewhere in a secluded place, where they remain in a daze. Some types of spiders tolerate low temperatures well and during winter thaws they can be seen crawling through the snow under trees.
Small spiders live 1 year, large ones - 2-3 years.
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Web of the cross spider
Cross spiders catch their prey using webs. More precisely, their females - male spiders do not weave webs. Female spiders guard their prey either in the center of the web or sitting next to it, on a signal thread. Mostly flies or mosquitoes get caught in the web. If it comes across prey that is too large and inedible, for example a wasp, the spider can free it by tearing off the web.
The spider either eats the caught prey immediately on the spot, or, if it is not too hungry, drags it into a secluded corner or entangles it in a web. Around the web, under the leaves, you can find a whole food warehouse of flies entangled in the web, stored for a rainy day.
Preparations for the winter
House spiders, which do not hibernate in winter, surprise with their activity. What can spiders eat in an apartment in winter? If you look closely at the nets they spread, you can see the remains of insects wrapped in webs. The predator prudently creates “storerooms” in cool, damp places, where they can be stored longer without drying out. If there is a “raw material base”, spider stocks are renewed throughout the cold period. The spider withstands long breaks in feeding, supporting itself with water and ceasing active movements.
The behavior of the cross spider
How does a spider hunt? When a fly or any other insect gets caught in a web, the spider senses the vibration of the trapping web, it crawls into the victim and kills it with a bite of its poisonous mandibles, or chelicerae. The fly stops shaking the web, and the spider calmly swaddles it with a bundle of thin threads, pulling them out of the abdomen with a pair of its legs.
Having snacked on the surrounding threads, the spider takes its breakfast and goes to the center of the web to have a meal. He crushes his prey, injecting digestive juices into it. When the fly has digested inside its shell, the spider sucks up the semi-liquid contents into which the fly has turned and throws away the victim’s skin. During a successful hunt, a spider can eat about a dozen flies in one sitting. The venom of cross spiders is dangerous only for small insects; it cannot harm humans.
Habitat of the cross spider
Crossworts live mainly in the crowns of trees, make a secluded shelter from the leaves, and stretch the web between the branches. The wheel-shaped web can be found in a forest, grove or neglected garden. Sometimes it can be found in bushes or in window frames and under the eaves of abandoned houses.
The trapping web constantly requires repair, it is destroyed by both small and large insects, so every couple of days the cross spiders unravel the web and make a new one. They usually do this at night, and by morning the new web is ready for new prey. Thus, at night the spider is relatively safer, because its natural enemies, insectivorous birds, sleep at night. It does not need light to build a web; a well-developed sense of touch is sufficient.
The enemies of the cross spider are also flies and wasps, which lay eggs in the bodies of their victims. For example, the fly Melanophora rugalis - taking advantage of the spider’s immobility, it can fly up to it, sit on its back and in the blink of an eye lay an egg in its body.
Web of the cross
The web of the female cross has exactly 39 radii, 1245 points of attachment of the radii to the spiral and 35 turns of the spiral - no more, no less. The webs of all spiders are as similar to one another as two peas in a pod, because all the necessary data is genetically enshrined in their heredity. Therefore, even small spiders know how to build webs and catch prey.
Any web is not only beautiful in its symmetry and delicacy, it is very rationally arranged. All the threads that form it are very light and, nevertheless, very strong, and are connected in such a way that they only work to break.
How does a spider manage to build such an even, symmetrical web that is several dozen times larger than itself? A spider (more precisely, a cobweb), having climbed onto a branch or tree trunk, releases a long web thread from its abdomen. It is picked up by a stream of air, and the spider waits patiently until the thread catches on something suitable.
If this does not happen and the thread hangs, the spider pulls it towards itself and eats it. Then he runs to another place and tries again. And so on until the thread is caught. Then the spider crawls to the hooked end of the thread and secures it well. Then it descends on its thread to some support. There he also firmly fastens this thread - now 2 threads are already fastened.
The spider returns along the second thread and drags along the third, which it secures at the starting point, i.e. where the first thread came from. The triangular frame - the basis of the future web - is ready. Inside this frame, the spider stretches several threads that intersect in the center. The spider marks the center of the web with a lump and begins to extend all its numerous radii from it, fastening them with a spiral thread, and then lays trapping threads. At the intersection points of the spiral and the radius, the spider binds them with its legs.
Note that the angles between all radii and the distance between the turns of the web are strictly constant values. How does such a small creature manage to maintain its web in strict accordance with geometry? For this you need at least the simplest measuring device. And, imagine, the spider has it! This is his first pair of legs that can act as a scale ruler.
While working on the web, the crossmaker regularly checks the distance between the spirals. His natural tool is so precise and reliable that it allows you to work in pitch darkness. The last step in creating a web will be a signal network, the end of which is laid to the spider’s shelter. To build the entire web, the spider requires several hours of painstaking work and approximately 20 meters of web.
From a chemical point of view, the web is a complex protein polymer - fibroin. The many glands of the spider's abdomen form this viscous liquid, which quickly solidifies in air in the form of thin filaments. The spider can produce several different types of web with different properties. For the frame of the web he makes a dry and thick thread, for the cocoon - silky and soft, for the catching spiral - thin and sticky. Why doesn't the spider itself stick to its web? Everything is very simple - he runs only on non-adhesive threads, and diligently avoids touching adhesive spirals.
The polymer liquid comes out from the glands on the spider's abdomen through thin tubes and hardens into very thin threads. If the spider needs special strength, it can weave several of these threads together. In recent years, scientists have been seriously studying the properties of spider “silk”. It turned out that it has many unique properties.
The technology for producing spider web threads is similar to the production of synthetic fibers. But in terms of strength, no synthetic fiber can compare with spider fiber - it can withstand loads of up to 260 kg per 1 sq. mm, which is stronger than steel. This is why residents of the tropics make nets from spider webs to catch birds, bats, insects, and even weave fishing gear.
The web is so elastic that it can stretch up to 30% of its length and shrink back to its original length. Its lightness and subtlety are involuntarily amazing, because 340 grams of web is enough to encircle the globe at the equator!
Temperature of keeping tarantulas
The body temperature of the spider, and therefore the intensity of metabolism and other functions of its body, is directly dependent on the ambient temperature.
The optimal temperature for keeping tarantulas ranges from 20-25°C (for tropical forest species) and up to 26-28°C for some inhabitants of arid biotopes ( group 4 ), but minor temperature changes in one direction or another do not harm tarantulas any harm. Moreover, even in places where their habitats experience high temperatures, they are usually stable in burrows and do not reach such high temperatures.
In the case of certain species of group 2 of up to 14-15 ° C is permissible , and for Megaphobema mesomelas from the mountain cloud forests of Costa Rica the temperature is higher 23-24°C can be fatal (observation for natural individuals).
A drop in temperature below 18°C for species of group 3 (except for burrowing Asian tarantulas, which for successful breeding need to arrange a period of rest at low temperatures), and especially tarantulas inhabiting the biotopes of lowland tropical rainforests, living in nature in deep burrows, where the temperature is sufficient stable and amounts to 20-24°C (Striffler, B., 2006; Cloudsley-Thompson et al., 1984) depending on the depth of measurement from the surface of the substrate, as well as representatives of group 4 (inhabiting arid biotopes of Africa) is extremely undesirable . At the same time, drops of 3-5°C and even lower do not affect tarantulas in any negative way if the spiders are not fed.
Observations in captivity show that during the summer, when the ambient temperature rises sharply (above 30°C), the tarantula can be seen immersed in containers of water for drinking.
This behavior is especially typical for burrowing tropical tarantulas (Theraphosa spp., Megaphobema spp., Nhandu spp., etc.), for which a significant increase in temperature is also extremely undesirable as is its significant decrease (since their habitats are not subject to strong temperature fluctuations).
Therefore, when choosing temperatures for keeping, it is necessary to take into account the characteristics of specific species of tarantulas. But for the most part, tarantulas do not require additional heating and are quite content with average room temperature for normal life and development.
Moreover, it has been noted that the practice of “forced” rearing of tarantulas at elevated temperatures with intensive feeding leads to adverse consequences for their further development and reproduction. So, for example, the productivity of giant males and females is much lower than those raised under normal conditions.
On the other hand, the possibility of artificially regulating the temperature of the housing has its advantage, since it allows you to control the growth rate of spiders, which is important when breeding tarantulas due to the limited number of individuals of one species, if there is only a limited number of individuals of a species from one cocoon.
It should be noted that tarantulas bred and raised in captivity are more flexible in relation to the maximum and minimum temperatures of maintenance than specimens directly obtained from nature.
The use of cobwebs in agriculture and medicine
People have long tried to make fabric based on spider webs. In Germany, back in the 16th century, ribbons and various decorations were woven from cobwebs in villages. Then in France, artisans came up with the idea of making gloves and stockings from spider webs, which caused complete delight among fashionistas.
But it turned out to be impossible to launch this technology into large-scale production, and this was convincingly proven by the physicist and zoologist Reaumur. For such production to become profitable, it is necessary to contain and feed hundreds of thousands of spiders. But to feed them, it would be necessary to catch several million flies every day, which was completely impossible to implement in practice.
However, people still use the web, even today. For sights (crosshairs) in various optical instruments (microscopes, telescopes, sights, etc.), spider webs are simply ideal. Microbiologists have also found use for it, developing a unique air analyzer using it.
The cross spider is launched onto a special frame, fed, and the spider weaves its web based on this frame. Then air is pumped through a frame with a net, and the thinnest web perfectly captures the microbes that are in the air. This method of air analysis has been recognized as the most effective of all existing in the world.
In folk medicine, spider webs have been used since ancient times to disinfect open wounds. Research has confirmed that spider webs kill pathogenic bacteria, and with its help, drugs have been developed that are harmless to animals, but deadly to all kinds of bacteria. As you can see, the cross spider is extremely useful for humans, in every sense.
