Orb-weaving spiders. Species composition of orb weaving spiders Man and orb weaving spiders
Orb weavers are spiders whose weaving technique can delight even a professional weaver. Once, scientists even conducted a funny experiment - they sent two representatives of this species to one of them. What was their surprise when these creatures, even in conditions of complete weightlessness, managed to create a web of ideal shape and structure.
What else do we know about these spiders? For example, where do they live? What do they eat? And how dangerous are they for people?
general information
Orb weavers are spiders, whose family includes more than 3 thousand species. Considering this, it is safe to say that they are in the lead among similar beings. However, this also means that it is quite difficult to give them general characteristics. Indeed, despite some similarities, their external differences can drive even an experienced researcher into a stupor.
What unites them all? The correct answer is a web, all spinners weave it. Spiders of this species, despite all their differences, create networks of a similar shape. It is difficult to confuse it with the creations of other arachnids, since it has almost perfect shape. Looking at it, you can clearly distinguish both the main threads and additional ones, in the form of circles.
The appearance of spiders
These representatives of arachnids boast the richest set of skin tones. They can be both snow-white and poisonous green. In general, the color of their body depends on the habitat and serves as a kind of natural camouflage.
But there is also something that does similar friend on each other of all representatives of the species Orbweavers. Spiders of this family have a large abdomen, which in its volume greatly exceeds the cephalothorax. Also on the front pair of paws there is a special process, thanks to which they weave their web.
habitats
Trapping webs of orb-weaving spiders are scattered all over the world. They can be found in both Northern and South America, in Africa, Europe and even Australia. Some representatives of this species feel quite confident on the territory of Russia. In particular, the most common is the cross-spider.
If we talk about the preferences of these arachnids, then we can say with confidence that they like quiet and cozy corners, hidden from prying eyes. Therefore, they try to weave their web in those places where contact with the human world is minimal.
However, sometimes they can change this rule. The reason for this is the desire to find lands rich in food. Therefore, do not be surprised that the orb-web spider decided to settle in the garden or in the garden. Indeed, in such places there is a lot of prey, which, by the way, is often a pest.
How does a spider spin its web?
As you might have guessed, the orb-weaver needs a web not only for the sake of aesthetic pleasure. In practice, this is a powerful trapping mechanism, honed over many centuries by evolution. How does it work?
The construction of a new network begins with the fact that the spider launches one end of its web into the wind in the hope that it will catch on, for example, a tree. After the goal is reached, the spinner, using the newly made bridge, begins to weave other branches of the web.
At the same time, he has two types of threads in stock. One is strong and elastic, the second is sticky. The first he uses to build the frame of the web. The second one is wound in circles in a spiral in order to cover as large an area as possible.
A signal thread runs along the entire web, the vibrations from which are able to inform the hunter that the victim has flown into a trap. After that, he only has to wait a little while the prey is finally entangled in the network.
What do Orb Weavers Eat?
The basis of the diet is made up of insects that managed to get into the net. In this case, the spider will rarely attack immediately. In most cases, he will wait until the victim is a little tired and stops fluttering, after which he will approach him.
The orbworm does not eat the whole prey. He injects special toxins into her, which corrode the victim from the inside. Then he just drinks the contents, as if thick soup, and the rest drops down.
or not?
Many are interested in how dangerous it is for others, including people. Well, this arachnid has poisonous glands. But its toxins are only dangerous for insects and small mammals. In particular, it can cause paralysis in them.
As for people, it is not fatal for them. But the pain from him will haunt the poor fellow for a long time. True, spiders rarely bite people, it is much easier for them to jump to the ground and run away than to get involved in a senseless fight with a giant.
cross spider
In Russia, there is also a spider-web. Photos of this arachnid are presented in the article. His name is a cross. In general, this species of orbweaver is not much different from its relatives. He got his name thanks to the pattern on his belly in the form of a cross. You can meet him both in the forest and in an ordinary park.
They are often hard to spot because they hide from people. But with the advent of autumn, everything changes - they begin mating season. At this time, the females weave webs in the most prominent places so that the male does not miss them. And only with the advent of the first cold weather, they again hide in their shelter.
The horned spider, or spiky orb-weaving spider (lat. Gastercantha cancriformis) belongs to the Araneidae family.
This little spider looks like a crab. Latin name species cancriformis translates as "crab", and the name of the genus is formed from two words gaster and acantha, which means "belly" and "thorn".
Spreading
This species is widely distributed in Costa Rica, Peru, Mexico, Ecuador, Honduras, Guatemala, Cuba, Jamaica and El Salvador. In the USA, it is often found in California and Florida, especially around the city of Miami Beach and along the coast. Atlantic Ocean. Separate populations inhabit many islands in the Caribbean Sea and the Gulf of Mexico.
AT last years the horned spider was also found in Colombia and Dominican Republic. To date, two subspecies of G.c. cancriformis G.c. gertschi.
Behavior
The spiny orbweb spider prefers to settle in mangrove forests and wet areas on trees and shrubs. Differs in enviable diligence. Every evening weaves a new network in the form of a circle, in adult females it can be up to 30 cm in diameter.
It is placed on the branches in an almost vertical position, most often at a height of about 6 m above the ground, and the animal itself, waiting for prey, is at the bottom of its hunting structure.
Smaller males live on threads placed near the female's nets. They do not hesitate to sometimes feed on her trophies, after rhythmically tapping their paws on the threads. Such courtesy allows them to stay alive and not be eaten by mistake. Up to three gentlemen can feed from their girlfriend's table at the same time.
The diet consists of all kinds of flying insects. Fruit flies, whiteflies, beetles and night butterflies become prey.
reproduction
Until now, there is no reliable information about the features of the reproductive behavior of horned spiders in wild nature. All data obtained only as a result of laboratory observations. It is not known whether a female naturally mates with only one or a few males.
The mating season occurs in late spring or early summer.
The gentleman who decides to continue the family warns the lady of the seriousness of his intentions with four quick blows to the edge of the net. He repeats them until the beauty demonstrates her attitude towards him. If she does not like the applicant, then she will simply drive him away.
In case of a positive answer, the male approaches his chosen one and, in order not to fall, joins her with a thread. Mating lasts about 35 minutes and is repeated several times with short breaks.
In autumn, the female lays eggs in the amount of 100 to 260 pieces in one oblong cocoon of a golden or less often greenish color. It attaches nearby on the underside of the leaves.
The cocoon is attached first with thin whitish and yellowish threads, and then with thicker and stronger dark green ones. All this structure is additionally equipped with a special canopy.
After the construction work is completed, the mother dies. Its life expectancy does not exceed one year. Males live for about 3 months and die one week after mating.
Spiderlings hatch in winter and continue to be together for two to five weeks, and then scatter in different directions.
Description
The body length of females is 5-9 mm, and the width of their abdomen is 10-13 mm. The main background of the opisthosoma varies from white to orange, in some regions it can be black. Six spike-like processes extend from it, which are black or red. They are located along the edges of the opisthosoma in a diagonal order. Sometimes the tips of the spikes are colored orange.
The shape of the spines and coloration have many regional differences depending on the habitat. The upper part of the opisthosoma is covered with miniature blackish dots like craters arranged in four rows.
The body length of males is 2-3 mm. It is more elongated than wide. The abdomen is gray, covered with white spots. The spines are weakly visible, they can hardly be distinguished no more than 4-5 pieces. The legs are short.
The bite of this horned spider is not dangerous for humans. It causes short-term pain, swelling, and redness of nearby tissues.
- Class: Arachnida Lamarck, 1801 = Arachnids
- Squad: Araneae = Spiders
- Family Araneidae = Orb-web spiders
From the personal life of orb-weaving spiders
* Read more: Orb-weaving spiders; cross spiders; Curious Facts About Spiders
The evolution of spiders went primarily along the line of changes in behavior, and not in morphology. Therefore, there are so many works on the biology of reproduction, network building and other aspects of the life of spiders. And something new is being discovered all the time.
Arachnologists T. Bukowski and T. Christensen, studying the biology of the North American orb weaver Mecrathena gracilis, which belongs to the group spiny orbs and has numerous spiny outgrowths on the abdomen, two features of their reproduction were found out.
First, the male climbs into the net to the still immature female, shortly before her last molt. He molts fewer times than the female, and becomes sexually mature earlier. This is beneficial: a female that has not yet molted or has just molted is less aggressive. Perhaps, over time, she "gets used" to the presence of a male. Analyzing the condition of males sitting in the nets of females, American researchers found the absence of part of the legs and other injuries in only a small proportion of males. At first, the males behave passively and sit at the edge of the web, apparently fearing the attack of the females. After mating, the male quickly runs away, often even jumping out of the female's web. (Similar male behavior is known in many web spiders, including orb weavers.)
Secondly, two-time mating is characteristic of micrates: at first - short, and repeated - twice as long. In this case, the male tries to fertilize the female through both of her paired copulatory openings. Most likely, this is necessary to guarantee the appearance of exactly her own, and not someone else's, offspring - after all, the female is then able to mate with other males waiting in other corners of her network. Males try to remove competitors by cutting off their web threads, etc.; they themselves, by the way, can also mate with several females.
However, it remains unclear whether the sperm of the first male has an advantage in fertilizing the female, as has been noted in many other spider species. If it does, then the second pairing becomes unnecessary. Perhaps, for the first time, the male “out of excitement” introduces an insufficient amount of sperm? It is also not clear how the male monitors the age of the female. It is hypothesized that from time to time the male visits the growing female, and climbs into her net already "closer to the point" - before the last molt. But so far this hypothesis has not been proven.
Accompanies us in life great amount Living creatures. We love a kitten or a puppy, but a cockroach or a spider is disgusting to us, and we don’t even think about whether they are useful or harmful. We won’t say anything good about the cockroach, but we’ll try about the spider. They live everywhere - high in the mountains, in the desert, in the forest and in the meadow, even in the water. Spiders are not found only in permafrost Arctic and Antarctic. The conquerors of Everest found one of the species of spiders at an altitude of 7 km, and in the taiga there can be up to 300-350 small spiders per square meter of soil.
They have been and remain constant neighbors of man for many millennia. When man first settled in the cave, spiders already lived there. But mostly harmless spiders cause many people to have superstitious fear, the roots of which go back to ancient times.
The Apulian tarantula, thanks to a misunderstanding, even became famous throughout the world. The tarantella is named after him. This dance, widespread in the south of Italy, without which no one can do folk holiday, was born in Apulia sometime between the 13th and 18th centuries AD. e. Its appearance is associated with a method of treating a disease that has been practiced since ancient times, from which, at the height of summer, primarily young guys who worked in the fields suffered.
Among the many thousands of species of spiders, there are only a few whose poison is dangerous to humans. For example, outwardly scary spiders Sigella and Cyclose are actually completely harmless. Benefits for a person, for example, bring more than harm. For example, in traditional medicine fresh cobwebs have been used since ancient times as a plaster. It stops the bleeding and disinfects the wound. Some tropical spiders weave a web so strong that the natives use it for fishing nets and nets. AT Ancient Rome doctors often recommended that the patient wear a spider pouch around his neck to cure malaria and other diseases. Here is a similar recipe from a medical reference book compiled by a certain Watson back in 1750: “Cover a live spider carefully with bread crumb, but so as not to damage it, and let the patient swallow quickly. This is a very effective medicine...”.
Spiders are united with scorpions and mites in the class of arachnids and belong to the type of arthropods, like insects and crayfish. The name of a class of arachnids and refer to a type of arthropod like insects and crayfish. The name of the arachnid class (Arachnoidea) comes from the Greek arachne - spider. The ancient Greek myth tells about a girl named Arachne, who dared to compete with the goddess Athena.
Spiders are the largest group of arachnids. More than 20,000 species of them have been described, and experts believe that this figure will increase significantly in the future, as the spider fauna the globe studied very unevenly and incompletely. All land is inhabited by spiders. Like insects and mites, they live everywhere, and there is literally no corner in nature where there would not be certain types of spiders.
In order to move on to a more detailed consideration of spiders, let's try to immediately understand the nature of this huge detachment and the features of its diversity. Indeed, in all the main life manifestations that support the existence of the species - obtaining food, reproduction, resettlement and experiencing adverse conditions - spiders use the web. A shelter and a dexterous device are made from it, with its help a complex mating procedure takes place, an egg cocoon is woven from it and a wintering bag on it is carried by the wind, etc. The spider interacts with the outside world not so much directly as other animals, through its cobwebs. adaptations, which in each species correspond to its vital needs and the specific environment in which it lives. In other words, relationships with environment carried out in spiders through arachnoid activity, which, like all the behavior of spiders, is based on instincts. A comparative study of spiders shows that the evolution of arachnoid activity, the evolution of instincts, is the leading direction evolutionary development spiders, on which this peculiar detachment reached an unprecedented flowering.
A clear confirmation is the nature of the diversity of spiders. Gossamer adaptations represent evolutionary ranks from very simple to extremely complex and perfect, whether they are egg cocoons, lairs and nests, or trapping nets. At the same time, the building of cobweb devices is becoming more complicated. It's great that general type At the same time, the structure of the spider is steadfastly preserved. The sizes of spiders, color, external form are different, the structure of individual organs changes, but all this endless diversity is contained within the framework of a certain stereotype. A spider is always a spider. Unity is also maintained in a number of features of biology, such as nutrition, individual development etc.
The body of spiders is divided into two sections: the cephalothorax and the abdomen. 4 pairs of legs are placed on the cephalothorax, and 4 pairs of eyes on top of the head. A pair of short tentacles is directed forward; in males, the ends of the tentacles are thickened.
A characteristic feature of all spiders is the ability to secrete a special liquid from the warts at the end of the abdomen, which immediately solidifies into a web. The web is different depending on the purpose. From it, spiders make webs to capture prey, weave a shelter for themselves, make a cocoon to protect eggs, and use it for settling.
All spiders are carnivores, feeding mostly on insects. They get them either by lying in wait, or actively pursuing, or using trapping nets. The shape of the trapping nets different spiders different. To kill prey, spiders use curved hook-shaped jaws (chelicerae), with a channel inside through which poison flows into the body of the victim. (AT middle lane There are no spiders dangerous to human life in our country, but the bite of some spiders can be quite painful.)
After laying eggs, the female either guards the cocoon with eggs while sitting in the shelter, or drags it with her.
Young spiders emerging from eggs usually first hold together and then scatter. In some species, they tend to climb somewhere higher - on fences, bushes, trees. Here they release a small light cobweb, which is picked up by the wind and, together with the spider at its end, is carried away. This is how the settlement of young spiders occurs. This usually happens in the fall, during the "Indian summer", and then everywhere on the bushes and fences we see cobwebs shining in the sun.
Adult spiders die after the end of the breeding season.
Family of spiders - orbweavers (Araneidae)
Spiders with a thick abdomen, significantly exceeding the thickness and width of the cephalothorax. The legs are short and thick, adapted for gliding on the web.
They move slowly, in case of danger they often fall to the ground. The trapping net is wheel-shaped, with a middle filled with a net. Spiders sit either on a trapping net or nearby in a shelter.
Typical representatives are cross-spiders (Araneus), of which there are about 20 species in the middle zone of the European part of Russia. We stumble upon their network on the paths of gardens, parks and forests in July - August. Most often they belong to females. We give a description of the females of the most common and common species.
Common cross (Araneus diadematus)
The greatest width of the abdomen in the front. Light spots are located here in the form of a cross, on the back of the abdomen there is a dark leaf-like pattern. Legs are yellow, with dark rings. Size 14 - 16 mm. A spider waiting for prey sits in the center of the web. Inhabits forest edges, clearings, woodlands. The trapping net is spread at a height of 1.5 - 2 m.
Marble cross (Araneus marmareus)
The abdomen is oval, its greatest width is at the middle. Light (sometimes red) spots forming a cruciform pattern of the abdomen, steeply oval. Legs with reddish rings. Size 15 - 20 mm. A spider waiting for prey sits on the side of the trapping net, in a shelter made of rolled-up leaves. There are more than 30 radii in the network. Habitat and distribution, as in the common cross.
Four-spotted cross (Araneus quadratus)
It is similar in size and general background to the two previous species. The abdomen is spherical, in the anterior part with four rounded light spots or with four dark dots on a light background. The leaf-like pattern in the back of the abdomen is blurred.
It occurs in open wet places: in meadows, swamps with high grassy vegetation, along river banks. There are 20 - 28 radii in the trapping net. The spider sits in a shelter on the side of the web, where the signal thread leads.
Widely distributed throughout Russia.
Striped orbworm (Singa nitidula)
A small spider, 5 - 6 mm in size, with a rolled abdomen. The cephalothorax is brown, the abdomen is light, with two wide dark longitudinal stripes.
Common in places with moist grassy vegetation. The trapping net is stretched among the grass, not high above the ground. The spider sits on the side of the net in a shelter made of a green leaf folded into a corner.
Widely distributed throughout Russia.
Despite the awesome appearance orb-weaver spider in the photo, a description of its life cycle debunks the myth of the extreme predatoryness of the animal and the danger to humans.
According to the international taxonomy of animals, the genus of Nephila spiders (Nephila) is included in the family, which has two synonymous names at once:
- ancient Greek Nephilidae;
- latin
In the Russian-language version of the classification of arthropods, they are called Orb-weavers.
Any of the names of these spiders fully corresponds to their abilities: if the Greek nema- and -philos are literally translated as “loving to weave”, then the Russian one indicates the circular shape of the trapping network of this category of arachnids.
The appearance of a typical representative
The entire structure of the spiders of the genus Nephila (hereinafter in the text: spiders-nephiles, or nephiles) is adapted for unhindered, easy and rapid movement.
Spider-web spider according to the photo and description has:
- incredibly long legs, allowing you to take huge steps;
- extremely light weight relative to the huge total area supports with widely spread paws.
The area of the end segment of the leg is so small that for it the thin fiber of the cobweb serves as a completely reliable support.
Spider weaver
Given the fantastic strength and degree of elasticity of the threads of the trapping net, it is not surprising that the orb-web spider walks along the structure it has built as easily as a person skis on snow.
When looking at its narrow and as if streamlined body, a comparison with a racing car suggests itself, next to which the sometimes huge body of a caught victim seems like a clumsy bulldozer or excavator.
A scattering of small spots of bright color on the abdomen and legs, visually splitting the body into separate fragments, perfectly masks the predator, even located in the very center of its trap.
Where are the nephiles found
Despite the prevalence of nephil in the world, each species lives in conditions that are comfortable for it. So, the garden orb-web spider is considered a typical representative fauna of Australia.
And if a spiked orb-weaving spider (also called a horned orb-weaving spider) cannot meet a Russian citizen either (because it lives in humid and sultry tropics), then for Argiope lobata the orb-weaver spider is inhabited by semi-deserts and steppes of Crimea, Central Asia and the Caucasus.
At the same time, the green orb-web spider (or Araniella cucurbitina) is a rare but common inhabitant of the forest, where it can be found at the very beginning of summer.
Spider Araniella cucurbitina
The most common orb-web spider found near human habitation is an ordinary cross, the details of whose life are well studied by arachnologists - biologists specializing in the study of arachnids.
About the life cycle and reproduction of nephil
males different types Nephil spiders can be up to 10 times smaller than the female. Their life also does not differ in duration - after mating, they are usually killed and eaten by recent sexual partners, with special luck, the male manages to fertilize several spiders during the season.
Sometimes they have to patiently wait a few weeks until the future "wife" sheds, during this period of life she is less belligerent.
An example of spider eggs
Carefully sealed in a dense and warm cocoon, laid and hidden in a secluded place, the eggs overwinter, so that offspring hatch from them in the spring.
Being passive predators, spiders wait for a small animal to get into the network they have built, which is killed by the secretion of poisonous glands. Its enzymes, injected upon bite, cause the body of the victim to be digested while the spider rests in the nest.
Orb-spin tetragnathoides catching a hornet in its web
After the required time has passed, it returns to suck out the liquid formed inside the chitinous shell of the prey from the action of the poison's enzymes.
About traps and catchers
Home distinctive feature nephil from other families of spiders is the ability to build within 1 hour a trapping network of a huge area (up to 1 m in diameter), which has a regular radial-spiral structure (hence the name "orb-web spider").
The weaving of trapping nets and their skillful use is the main occupation of the life of the Nefil. So, if stuck to the web poisonous insect(wasp, bee), the threads around the dangerous prey break. The threads that have become unusable are eaten by the spider to serve as material for a new trap.
It is a spider, because, given the preoccupation of males with the abandonment of offspring, they themselves do not knit a web, or they have it in the form of a disorderly structure with randomly tangled threads.
Ladybug caught in a web
But built by the female, it is distinguished by impeccable proportions, and the shape, size of the cells, the thickness of the thread is adjusted to the expected size and resistance of future prey. The shape and size of the grid also depends on the weather and the time of year.
In addition to sticky threads, the design of the trap also includes dry silk threads - spiders run along them without sticking.
Spider of the family araneidae
The unheard-of strength of spider silk proteins (with 5 times the tensile strength of steel wire) and its elasticity (greater than that of nylon) serve as the basis for the existence of both individual members and the entire Araneidae family.
On the danger to humans and the value of spiders for wildlife
The toxicity of the venom of orb-weaving spider species (any) is designed only for killing prey, therefore chemical substances, which are included in it, are not dangerous for human life, although they can cause sensitive pain.
In addition to ensuring their own survival, arachnids provide wildlife with an essential service.
They participate in the process of evolution, regulating the number of some animal species, among which the strongest and most adapted to living in given conditions survive.
As for a person, the number of certain types of insects (planting pests, disease vectors and other categories) is also important for his activities, especially when living in hot tropical countries.
Video: Amazing Spiders (Spider-web)