Spider cross description for children. Cross spider

Habitat and external structure of the cross spider

In the garden or in the forest in the summer, walking along a narrow path, we often come across cobwebs. This is most often the trapping net of a cross spider. Often the eight-legged builder himself sits in the center of his wheel-shaped network. Its body has a sharp transverse constriction in the middle - a stalk, or waist, separating a small front part called cephalothorax, from the back - smooth spherical abdomen. The abdomen on top of a dark background has a cross-shaped pattern (hence the name of the spider - cross). On the upper side of the cephalothorax in front there are organs of vision - 8 simple eyes. 8 walking legs extend from the cephalothorax from below, and the oral organs are noticeable in front of them, namely: the first pair - jaws, second pair - foot-tentacles. The tentacles have sensitive hairs that are part of the organs of touch.

Drawing: External structure cross spider. The catching net of the cross spider.

The spider is a predator; it is armed with devices for killing victims, which most often are various flies. Each jaw at the apex has a segment in the form of a sharp movable claw. Venom glands that produce poison are located under the base of the jaws. When the jaws pierce the body of the victim, poison is sprayed through the openings of the jaw claws and kills it.

All abdominal segments are fused together. Three pairs are visible at its posterior end spider warts, which open arachnoid glands. The semi-liquid substance they secrete hardens in air, forming spider threads. The spider connects them using the comb-like claws of its hind legs into one common thread.

Cross spider's catching net

The female cross spider builds a large hunting net from cobweb threads, stretching it vertically between the branches of bushes, near fences and in other places. First, a polygonal frame with rays converging in the center is constructed from thick, non-sticky threads. The spider weaves a long, thin and very sticky thread to this base, arranging it in a spiral.

Hunting of the cross spider

While waiting for prey, the spider is usually located near the net in a hidden nest made of cobwebs. A signal thread is stretched from the center of the network to it. When a fly, small butterfly or other flying insect gets into the net and begins to fight in it, the signal thread vibrates. At this sign, the spider rushes from its shelter to its prey and thickly entangles it in its web. He plunges the claws of his upper jaws into it and injects poison into the victim’s body. Then the spider leaves the prey for a while and takes refuge in a shelter.

Feeding of the cross spider

The contents of the poisonous glands not only kill prey, but also act on it as digestive juice. After about an hour, the spider returns and sucks up the already partially digested liquid contents of the prey, of which only the chitinous cover remains. The spider cannot eat solid food. Thus, in spiders, preliminary digestion of food occurs outside the body.

Figure: internal structure of a cross spider

Breath of the Cross Spider

In the anterior part of the abdomen lies a pair of pulmonary sacs communicating with environment. The walls of the sacs form numerous leaf-like folds, inside which blood circulates. It is enriched with oxygen from the air located between the folds. In addition to the lung sacs, the spider has two bundles of respiratory tubes in its abdomen - trachea, opening outwards with a common breathing hole.

The circulatory system of the spider

The circulatory system of the cross spider is the same as that of the crab.

Reproduction of the cross spider

The female cross spider is larger than the male. In autumn, she lays eggs in a cocoon woven from a thin silky web. She weaves a cocoon in various secluded places - under the bark of stumps, under stones. By winter, the female spider dies, and the eggs overwinter in a warm cocoon. In the spring, young spiders emerge from them.

In the Arachnida class, the cross spider is a typical representative of these animals. You can find out more about the features of this species in our material.

Description and habitat features

There are more than 2 thousand species of cross spiders in the world. There are up to 30 species in Russia and neighboring countries.

A distinctive feature of this species are light spots on the upper side of the body, which form a so-called cross. This is where the name of the species came from - cross.

Rice. 1. External signs cross spider

The females of such spiders are much larger than the male. Its dimensions range from 17 to 40 mm, while the male is up to 11 mm long.

The animal's body consists of two sections: the cephalothorax and abdomen. The cephalothorax has 6 pairs of limbs, 4 of which are walking legs. On the abdomen, the limbs are modified into arachnoid warts.

Like most spiders, the cross spider is a predator. He catches his prey on a web, which he weaves quite skillfully. At the time of hunting, it can sit directly on the web, waiting for the victim.

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The digestion process partly occurs outside the animal's body. It injects its poison, along with digestive juices, into the prey and waits until the “dish” is ready. All that remains is to drink the nutritious liquid contents of the insect that is trapped. Favorite treats are small insects.

Rice. 2. An insect caught in a web becomes the spider's food.

Weaving a web

The cross spider settles in the crowns deciduous trees. It uses branches to form the basis of its nets, and leaves make an excellent shelter in which to hide. The web is usually large sizes placed both in the crown of a tree and on bushes.

After a day or two, the spider itself breaks its web, which becomes unusable, and builds a new one. The fact is that the web is partially spoiled by the prey itself, breaking the threads. It also contains dry leaves, which interfere with hunting.

The spider weaves a new web mainly at night. At this time of day, insects do not interfere, and there are no enemies who can eat the hunter himself. In construction, they are helped by the sense of touch, not sight.

In an adult female, the number of radii and spirals in the web has a certain number. The distance between the turns is also important. From observations it has been established that the spider web has:

39 radii;
spiral turns - 35;
spiral attachment points and radii - 1245.

Such accuracy is explained by a genetically inherent instinct. Even young individuals can weave a web with the precision of adults.

Rice. 3. Trap net

Is the cross spider dangerous?

The poison of the cross is toxic to both invertebrates and vertebrates. The cross is capable of biting through human skin, but the amount of poison injected into the body will be insignificant. Therefore, a bite may cause mild, quickly passing pain.

What have we learned?

The cross spider is no different in structure from other spiders. He hunts for webs, which he builds quickly and efficiently, updating them in a day or two. The venom of this spider is not particularly dangerous to humans.

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The cross spider (Araneus) is an arthropod belonging to the genus of araneomorphic spiders and the family of orb weavers (Araneidae). Today there are more than one thousand species of crosses in the world, which live almost everywhere.

Description of the cross

The external structure of the cross is represented by the abdomen and arachnoid warts, the cephalothorax and walking legs, consisting of the femur, knee joint, tibia, pretarsus, tarsus and claw, as well as the chelicera and pedipalp, acetabulum ring and coxa.

Appearance

Cross spiders are quite small spiders in size, however, the female of this arthropod is much larger than the male. The body length of the female is 1.7-4.0 cm, and the size of an adult male cross spider, as a rule, does not exceed 1.0-1.1 cm. The entire body of the cross spider is covered with a very characteristic yellowish-brown chitinous durable shell, shed during time for another molt. Along with most arachnid species, cross spiders have ten limbs, represented by:

four pairs of walking legs, with relatively sharp claws located at the ends;
one pair of pedipalps, which perform a recognition function and are necessary for holding caught prey;
one pair of chelicerae used in capturing and killing the caught prey. The chelicerae of the crosses are directed downward, and the chelicerae hooks are directed inward.

Adult males on the last segment of the pedipalps have a copulatory organ, which is filled immediately before mating with seminal fluid, which enters the spermatheca located on the female, due to which offspring appear.

This is interesting! The visual abilities of the cross are very poorly developed, so the arthropod sees poorly and is able to distinguish only blurry silhouettes, as well as the presence of light and shadows.

Cross spiders have four pairs of eyes, but are almost completely blind. An excellent compensation for such a visual deficiency is a well-developed sense of touch, for which special tactile hairs located on the entire surface of the body are responsible. Some hairs on the body of an arthropod are capable of responding to the presence of irritants. chemical type, other hairs perceive air vibrations, and third hairs pick up all kinds of surrounding sounds.

The abdomen of cross spiders is round in shape and completely devoid of segments. In the upper part there is a pattern in the form of a cross, and on the lower part there are three pairs of special arachnoid warts, which contain almost a thousand glands that produce arachnoid threads. Such strong threads have various purposes: building reliable fishing nets, arranging protective shelters, or weaving a cocoon for offspring.

The respiratory system is located in the abdomen and is represented by two pulmonary sacs, in which there is a significant number of leaf-shaped folds with air. Liquid hemolymph, enriched with oxygen, circulates inside the folds. Also included respiratory system tracheal tubes enter. In the dorsal region of the abdomen there is a heart, which with its appearance resembles a fairly long tube with branching, relatively large blood vessels.

Types of crosses

Despite the fact that there are a lot of varieties of cross spiders, only thirty species are found in our country and in neighboring countries, which are characterized by the presence of a pronounced “cross” located on the upper part of the abdomen. Frequently encountered species include the four-spotted or meadow cross spider (Araneus quadratus), which settles in wet and open grassy areas.

This is interesting! Of particular interest is the rather rare cross spider Araneus sturmi, which lives mainly in coniferous forests in the Palearctic region, whose modest size is compensated by a rich variety of colors.

The most widespread are also ordinary cross(Araneus diadematus), whose body is covered with a waxy substance that retains moisture, as well as a rare species listed in the Red Book called the angular cross (Araneus angulatus), which is characterized by the absence of a cruciform pattern and has a pair of small humps in the abdominal area.

How long does a cross live?

Cross spiders different types, compared to many of their brothers, they live for a fairly short time. Males die immediately after mating, and females die immediately after weaving a cocoon for offspring.

Thus, the life expectancy of male crosses does not exceed three months, and females of this species can live for about six months.

Spider venom

The poison of the cross is toxic to vertebrate and invertebrate animals, since it contains heat-labile hemolysin. This substance can negatively affect the red blood cells of animals such as rabbits, rats and mice, as well as human blood cells. As practice shows, they have a fairly high resistance to the toxin guinea pig, horse, sheep and dog.

Among other things, the toxin has an irreversible effect on the synaptic apparatus of any invertebrate animal. In most cases, crosses are absolutely harmless to human life and health, but if there is a history of allergies, the toxin can cause a strong burning sensation or local tissue necrosis. Small cross spiders are capable of biting through human skin, but total quantity the injected poison is most often harmless, so its presence under the skin is accompanied by mild or quickly passing pain symptoms.

Important! According to some reports, the bites of the largest crosses of some species are no less painful than the sensations after a scorpion sting.

Web of the cross

As a rule, cross spiders settle in the crown of a tree, between the branches, where the spider sets up large trapping nets. The foliage of the plant is used to make shelter. Quite often, spider webs are found in bushes and among window frames in abandoned buildings.

The cross spider destroys its web every other day and starts making a new one, since the catching webs become unusable due to the fact that not only small, but also too large insects get into them. As a rule, new network it weaves at night, which allows the spider to catch prey in the morning. The webs built by an adult female cross spider are distinguished by the presence of a certain number of spirals and radii, woven from adhesive threads. The distance between the turns located next to each other is also precise and constant.

This is interesting! Due to their very high strength and high elasticity, crosses have been widely used since ancient times in the manufacture of fabrics and various decorations, and among the inhabitants of the tropics they still serve as material for weaving nets and fishing nets.

The building instinct of the cross spider is brought to automaticity and programmed in nervous system at the genetic level, so even young individuals are able to very easily build high-quality web networks and quickly catch the prey necessary for food. The spiders themselves use exclusively radial, dry threads to move, so the spider is not able to stick to the trapping nets.

Range and habitats

The most common representative is the common spider (Araneus diadematus), found throughout the European part and in some North American states, where spiders of this species inhabit coniferous forests, swampy and shrubby plantations. Angular cross (Araneus angulatus) - endangered and very rare species, living in our country, as well as in the Palearctic region. The Australian cross spider Araneus albotriangulus also inhabits New South Wales and Queensland.

On the territory of our country, oak cross spiders (Araneus seropegius or Aculeira seropegia) are most often found, which settle in tall grass on forest edges, in groves and gardens, as well as in fairly dense bush thickets.

The Araneus cavaticus spider, or barn spider, uses grottoes and rocky cliffs, as well as entrance holes to mines and barns, to construct a trapping net. Quite often this species settles in close proximity to human habitation. The cat-faced cross spider (Araneus gemmoides) lives in the western part of America and Canada, and natural habitat India, Nepal, the territory of Bhutan and part of Australia have become a typical representative of the Asian fauna of the cross spider Araneus mitificus or the “Pringles spider”.

Food, catch of the cross

Cross spiders, along with most other spiders, have external type digestion. While waiting for their prey, spiders are usually located near the net, located in a hidden nest, which is made from strong web. A special signal thread is stretched from the central part of the network to the spider's nest.

The main diet of the cross spider is represented by a variety of flies, mosquitoes and other small insects, which an adult spider can eat about a dozen at a time. After a fly, a small butterfly or any other small insect falls into the net and begins to beat inside it, a noticeable vibration of the signal thread immediately occurs, and the spider comes out of its hiding place.

This is interesting! If a poisonous or very large insect gets inside the web trap, the cross spider quickly tears off the web to get rid of it. Also, crosses strenuously avoid contact with insects that can lay eggs in other arthropods.

An arthropod is unable to independently digest caught prey, therefore, as soon as a prey gets caught in the net, the cross spider quickly injects its very aggressive, caustic digestive juice into it, after which it wraps the prey in a cocoon of the web and waits for some time, during which the food is digested and turns into a so-called nutrient solution.

The process of digesting food in the cocoon most often takes no more than one hour, and then the nutrient liquid is absorbed, and only the chitinous cover remains inside the cocoon.

Araneus mitificus or "Spider Pringles"«

a typical representative of the Asian fauna, distributed from India, Nepal and Bhutan to Australia. A notable feature of the cross spider is exact copy a mustachioed face from a package of Pringles chips, located in the place of a traditional cross. These spiders hunt only from ambush, and their networks are always missing one section, but there is a signal thread stretched into the shelter. The size of adult females is 6-9 mm, males - 3-5 mm, but their modest sizes do not prevent spiders from proudly wearing the “face” of popular chips.

Araneus ceropegius, Aculepeira ceropegia)

lives in thickets of bushes and tall grass of forest edges, groves and temperate gardens climate zone. Oak crosses live in Europe, Russia, northern Africa, as well as in Asian countries north of the Himalayas, excluding Arabian Peninsula. Females and males are characterized by an abdomen pointed at both poles and a well-furred cephalothorax. The length of the female cross is 1.2-1.4 cm, the male - 0.7-0.8 cm. The upper side of the brown abdomen is decorated with a light herringbone, and below there is an elongated yellow spot.

or meadow cross(Araneus quadratus)

Found in damp, open grassy areas. Lives in Europe Central Asia, Russia, in Japan. The shape, size and color are very similar to the common cross. On the upper part of the abdomen, the cross spider has 4 round light spots or 4 dark dots, depending on the basic color of the body. Below is a blurry leaf-like pattern. The main body color varies from light green and carmine to black-brown. There may be light stripes on the paws. The length of females is 1.7 cm, males are half as long. Adult female cross spiders can change color and blend in color with their surroundings.

Araneus sturmi

a rare orb-weaving spider that lives mainly in coniferous forests in the Palearctic region (Europe, Russia, Asia north of the Himalayas, northern Africa). Maximum length the body of these spiders is 5.5 mm, females are usually longer than males: the length of females is 5-5.5 mm, the length of males is 4 mm. The modest size of the cross is compensated by the variety of colors. The usual color of individuals of both sexes is reddish-brown, but very beautiful, red-yellow-green specimens are found. Distinctive feature of this species of cross spider are “epaulets,” dark areas in the front of the abdomen.

(Araneus alsine)

typical inhabitant of humid deciduous forests temperate zone. Externally, this spider resembles a meadow cross and has 4 similar large spots on the abdomen, but differs in color, which is dominated by orange and beige tones. The spider's abdomen is dotted with small light spots, so the spider looks like a strawberry (hence its English name"strawberry spider" - strawberry spider). Females of the chilly cross grow from 7 to 13 mm, the length of males is 5-6 mm.

Reproduction and development of the cross spider

The mating season of crosses occurs in autumn, when sexually mature males wander through the forests in search of a female sitting in her web. Having found a suitable option, the male cross weaves a thread from the edge of the web, which serves as an escape route and at the same time an invitation to mating. The female recognizes such vibration as a signal for reproduction and leaves her network, and immediately after mating is completed the male dies.

The fertilized female cross spider builds a cocoon of soft silky threads, where she very soon lays eggs. She keeps the cocoon with herself for several days, and then hides it in a secluded place, hanging it in the cracks of the walls of residential buildings or under the bark of trees, where the cocoon will safely overwinter. After this, the female dies.

The offspring are born in the spring, and by summer the young spiders are already able to reproduce.

Photo taken from travelswithmusti.net

Due to their high strength and elasticity, spider web threads have been used for making fabrics and jewelry since ancient times, and tropical residents still weave nets and fishing nets from it.
The web of the cross spider is used in microbiology to determine the composition atmospheric air and as the thinnest optical fiber.
The cross spiders themselves move inside the web along radial, dry threads, so they do not stick to their own trapping network.

In the garden, forest and other places you can always see a fishing net cross spider(Fig. 75A). He himself either sits in the center of his web, or hiding in a shelter nearby on a branch or trunk. If we throw a fly or some other small insect, he will immediately run to the prey struggling in the sticky nets.

The cross spider is the most typical representative of the order Spiders, therefore it is characterized by most of the life processes of all spiders.

External structure

The body of the cross spider consists of two sections: a small, elongated cephalothorax and a large spherical abdomen, with a narrow interception between them. On the front of the cephalothorax there are 4 pairs of eyes located above, and below there are a pair of powerful jaws - chelicerae.

The top of each jaw has a movable sharp hook, with which the spider-cross spider grabs and kills prey. At the base of the chelicerae there are poisonous glands; from them a canal extends into the jaw, opening at the end of the jaw hooks. Near the jaws there are fingernails. They are thick, soft, covered with sensitive hairs - these are the tactile organs of the cross spider. On the sides of the cephalothorax there are 4 pairs of walking long legs.

The abdomen is spherical, smooth on top. The cross spider has a light cross-shaped pattern on the front - hence its name. There are no legs on the abdomen, but at the bottom end of the abdomen there are 3 pairs of arachnoid warts - from them the web is secreted.

The cover of the cross spider is chitinous and light. The body cavity is mixed (like a crayfish).

Rice. 75A. Cross spider

Trap net (web)

The cross spider builds a trapping network from sticky and non-sticky webs (Fig. 75B). The trapping net is built by females.

At the same time, he first makes a base in the form of an irregular polygon from non-adhesive strong threads. Then radii are pulled in this frame also from non-adhesive threads. Finally, the spider winds an adhesive thread in a spiral around these radii. The prey caught in the net (that is, stuck to the adhesive threads) struggles, trying to free itself. Feeling the shaking of the web, the spider runs towards the victim using non-adhesive radial threads. If a fly hits the net, the spider immediately kills it. If the prey is larger, for example, a butterfly, the spider first envelops it with a web secreted immediately so that it turns into a swaddled cocoon. Material from the site

Rice. 75B. Spider net

Nutrition

Having killed its prey, the spider does not immediately begin to eat it. He can only absorb liquid food. To do this, the spider lets a drop of saliva into the victim, which liquefies dense tissue. The saliva turns the fly's contents into liquid food and the spider sucks it out. If the prey is large, then the spider repeats the same technique several times, and, in the end, only an empty chitinous shell remains from the prey. All spiders feed this way.