IN undersea world with special equipment there was a diving bell. This structure was the prototype of the spacesuit. The oldest mentions of it date back to 1531. But thousands of years earlier, the Argyronet spider solved the problem of staying under water in a similar way.
The amazing house of the silver spider
The silver color of the spider is an optical illusion. The coloring of the argyronet is usual for most spiders - a cephalothorax and a brown abdomen covered with many hairs. It is these hairs, lubricated with a special secretion, that trap air when rising to the surface of the reservoir. Additionally, a tiny air bubble is transported at the tip of the abdomen, “caught” with the help of arachnoid warts.
It is a tiny semblance of a man-made diving bell. Attached to stems under aquatic plants cobwebs and a nest woven from them, reaching the size of a hazelnut, has a supply of air under the dome. An amazing spider, tirelessly diving for the next portion of silver bubbles, is freed from air reserves and can be underwater in its house.
The amazing insect weaves four types - for the bell, threads holding the nest, trapping nets and for the egg cocoon. Females build their nests with greater diligence than males.
Peculiarities of everyday life of the Argyronets
The underwater environment supplies silverfish with an abundant table, and small ones become prey for clever predators aquatic life. Sometimes they fall into the clutches of a hunting spider, sometimes they become entangled in the threads of the web. A well-fed Argyronet hangs its prey under the dome of the nest, wrapped in a cobweb cocoon, counting on bad days.
Here, under water, spider offspring are hatched. Having laid her eggs, the spider places them in an air-filled cocoon in or near the nest, and protects the precious clutch. A male spider that takes part in the fertilization of a female spider does not suffer the fate of being eaten by the female - an ending that is typical for the mating traditions of most arachnids. He continues to live nearby, in the same underwater bell, with the same eating habits, with the same air delivery responsibilities.
Arachnologists believe that among the reasons for refusing cannibalism is the male. Argyronets are the only kind spiders with a male having dimensions other than 1.5 and 1.2 cm, respectively. By the way, larger males have smaller nest sizes.
The silverback spider, an inhabitant of European water bodies, recently had its closest relative in Japan. As it turned out, the Japanese argyronet, previously considered a complete analogue of the European one, has much larger organs that perform reproductive functions.
The water spider (lat. Argyroneta aquatica) is the only spider in the world that has adapted to life under water. It belongs to the family of Cybaeidae spiders (lat. Cybaeidae) and is common in many regions temperate zone Europe and Asia up to the shores of the Pacific Ocean.
It settles only in reservoirs with clean and oxygenated water, where the bottom is densely overgrown with aquatic plants. Its favorite habitats are standing and slowly flowing fresh waters. Usually these are small lakes, ponds, peat bogs and river floodplains.
The water spider can also be kept in a regular aquarium. Underwater, it always retains a layer of air on its abdomen, so its abdomen looks like a drop of silver. For this reason, it is also called the silverback spider.
Behavior
Water spiders are friendly creatures and prefer to live in colonies. True, when kept in aquariums, if their numbers exceed the permissible limit, they become quite aggressive and devour each other. IN natural conditions There is enough space for everyone, so cannibalism among them is quite rare.
Each spider builds its own nest. Before its construction, he carefully studies the area and chooses the most suitable place among the aquatic vegetation at his discretion. Having found such a place, the spider spins a thick network from the web, the edges of which are attached to the stems of plants. Once the net is ready, he begins to fill it with air. The spider rises to the surface and emerges from the water hind limbs and the tip of the abdomen, between which a cobweb network is stretched.
With the resulting net, it picks up an air bubble and pulls it under the water.
The hairs of the furry abdomen also hold additional air bubbles. Having reached the nest, he rolls up air bubbles with his paws, which form an underwater bell above the net.
The hardworking spider makes forays to the surface until the entire network is filled with air. After this, you can rest and only replenish your air reserves as needed in the future. When the job is well done, the water spider can stay on the surface for up to two weeks, breathing oxygen collected in the underwater bell.
Argyroneta aquatica is a predator. Its prey includes larvae of mosquitoes and water insects, daphnia, small tadpoles and fry. Females most They spend time in the nest and even hunt with only half their cephalothorax out of it. Males are more active than females and often make daring forays into the midst of plants.
Having grabbed the victim, the spider injects a dose of poison into it and takes it to its bell.
There he introduces digestive juices into it, which liquefy the tissues. After waiting for some time, he happily drinks the resulting nutritious gruel.
As winter approaches, the water spider looks for an old shell and weaves a dense web around the entrance. The shell first floats on the surface of the water, but as it gets colder, the air in it is compressed, and it gradually falls to the bottom. A spider crawls into it and spends the winter well until spring.
In the spring, the shell floats up and is often transported by the current to another place. This is how spiders explore new territories. When the water in the pond warms up enough, the water spider leaves its winter quarters and begins building a new underwater bell.
Reproduction
IN mating season the male catches tasty prey and goes to the nearest female. If she likes the gift, he begins to build his bell next to her. Over time, their two bells merge into one.
The female lays eggs in the upper part of the bell, which is further strengthened by threads of cobwebs. Incubation lasts about 45 days under her watchful eye and guard.
The growing offspring remain in the nest until the fourth moult, feeding on the living creatures obtained by the mother.
The caring mother also constantly replenishes the air reserves in the bell. After the fourth molt, the spiders leave the mother's nest and become completely independent. They will become sexually mature by the end of the second year of life.
Description
Males are about a third larger than females. The body length of adult individuals ranges from 8 to 15 mm. The cephalothorax is yellow-brown. The abdomen is grayish-brown. The oblong abdomen is completely covered with delicate hairs.
The hairs contain a special fatty substance that repels water and allows air bubbles to be captured. The cephalothorax is wide at the junction with the abdomen, and noticeably narrows in front.
There are 4 pairs of walking legs attached to the underside of the cephalothorax. Spider warts are located at the end of the abdomen. On both sides of the mouth there are pedipal fingers, which serve as organs of touch. The first pair of limbs is transformed into chelicerae. The spider grabs and kills prey with its chelicerae.
Male water spiders live no more than 3-5 years, and females sometimes live up to 10 years.
The world's only underwater spider July 4th, 2015
Family representative Argyronetidae - Argyroneta aquatica the only spider that has perfectly adapted to underwater existence. Most often it occurs in standing or slow flowing waters, rich in vegetation.
Silver spiders adapt well to aquarium conditions. They can be kept in any vessels - both in glass jars (one copy at a time) and in large containers (several adult individuals). In this case, the presence of aquatic plants is mandatory, among which spiders build their homes.
Let's look at it in more detail...
Photo 2. 
By appearance The water spider is almost no different from its land counterparts. The body consists of a cephalothorax, where eight pairs of small eyes are located, and an abdomen, separated by a deep interception. The spider has four pairs of long jointed legs and two pairs of jaws: the first pair (chelicerae) serves to grasp and kill prey, the second (pedipalps) plays the role of jaw tentacles.
The silverfish breathes air, which it captures as it rises to the surface of the water. This occurs with the help of hairs that densely cover the entire body. They are fluffy at the ends and are not wetted by water. To prevent the hairs from sticking together, the spider lubricates them with a transparent secretion secreted by the chelicerae. Underwater, some of the air is trapped by the hairs, forming a silvery film of air (hence the name water spider).
Photo 3. 
The silverfish feeds on various small aquatic organisms - insect larvae, water donkeys, etc. When attacking, it envelops its prey in a web, digs into it with chelicerae and poisons it with secretions of poisonous glands. Then it injects digestive secretions and, after liquefying the tissues, sucks the contents out of its victim.
Photo 4. 
In captivity, these spiders can be fed with bloodworms, as well as flies, cockroaches and other insects that are thrown onto the surface of the water.
An interesting feature of silverfish is the construction of a dwelling - the so-called bell - from the secretions of the arachnoid glands. The necessary building substance is secreted, like in other spiders, from special glands - arachnoid warts located at the posterior end of the abdomen. The sticky liquid quickly hardens, turning into strong transparent threads. The air-filled web forms a bell.
Photo 5. 
This happens as follows. The spider weaves a network of web threads underwater, attaching it to aquatic plants and other objects. Then he begins to draw air inside, bringing it from the surface of the water. To do this, the spider crawls along plant stems and pulls a thread along which it returns, as an air bubble pushes it upward.
It takes about three hours to build a small bell. During this time, the spider rises to the surface up to 80 times. The air is held underwater by a spider web. The resulting dome reaches the size of a pigeon egg. There can be several bells in an aquarium different shapes. In them, spiders eat caught prey, take care of hairs, etc.
In nature, during the winter, spiders create a bell-cocoon underwater, in which they hibernate. In an aquarium, with enough food, they always lead an active lifestyle.
Photo 6. 
Typically, silverfish have males and females of almost the same size, but there is a species in which the males are much larger. Sex can be determined by the light gray coloration of the back of the body in females and a more elongated abdomen in males. Unlike other spiders, silverfish have a peaceful relationship between the sexes.
When breeding, water spiders lay eggs in an underwater cocoon that resembles a bell, but its walls are much denser. The masonry is located in the upper part of the cocoon and is secured with spider threads. The female guards the clutch and looks after it.
Photo 7. 
The spiders that hatch after 10 days do not immediately leave their mother. They molt, grow, and only then, emerging from the cocoon, scatter to begin building their underwater homes.
Juveniles are yellowish-gray or yellow-brown in color. With age, spiders darken and a black tint begins to predominate in color. In an aquarium, young spiders must be isolated from adults, since even the mother can eat them.
Photo 8. 
Since spiders emerge from the water and travel on land, when keeping them in captivity, it is necessary to tightly close the aquarium (jar) with a cover glass, leaving an air space above the surface of the water.
Photo 9. 
In order to breathe, water spiders build nests from webs that visually resemble domes - in these nests they store an air supply, and to replenish it they swim to the surface and from there carry air bubbles on their own hairs growing on the abdomen and legs.
Scientists have long established the ability of spiders to transport air bubbles under water, but no one had previously paid attention to the ability of a spider’s air capsule to absorb oxygen in water. Two Australian scientists Stefan Hatz and Roger Seymour tried to find out whether this feature is inherent in underwater spider nests that store oxygen. To understand how water can satisfy the oxygen needs of spiders, scientists began experiments. It was assumed that it is from water that spiders capture oxygen, the concentration of which in the domes decreases from time to time.
Most arachnids live on land, although there are exceptions. One of these exceptions is the well-known silver spider, which has secondarily adapted to life in water.
It’s not so easy to spot a spider in an ordinary body of water, but when you see it, you’ll recognize it right away. The observer's attention is drawn to the magnificent air bell in which the spider sits. Its entire abdomen fits inside the bell, part of the cephalothorax and legs are exposed - the silverfish lies in wait for prey. So he grabbed the water donkey, carried it into the air bell and began to eat. Having finished with the crustacean, the spider crawled out of the bell, threw out the remains of its prey and floated to the surface of the water. I wonder how a spider breathes underwater and why does it float to the surface from time to time?
What is interesting about the silver spider?
The water spider managed to arrange itself in such a way that it lives under water in air environment. On the ventral side it is covered with dense hairs: there are about 1,250 hairs per square millimeter of the surface of its body. All hairs are inclined back, some of them are longer, thicker, and sparsely planted, while others are shorter, thicker, and heavily pubescent. A layer of air is retained between the thick lower hairs, enclosing the spider's abdomen. The role of long thick hairs is to increase the thickness of the air layer adjacent to the spider's body. This is achieved by the fact that long hairs rest against the surface tension film of the inner wall of the bubble and move it away from the body, thus increasing the cavity of the bubble. In the female, the cover of hairs is evenly distributed over the entire abdomen; in males, part of the dorsal side of the abdomen is bare, so the shape of the air bubble in the male and female is different. To prevent the hairs from sticking together and perform their supporting role well, the silverback combs and lubricates them, wiping the body with the paws of its hind legs. Lying on its back inside the bell, the spider bends its hind leg and brings its tip to its mouth. Chelicerae begin to work, stimulating secretion transparent secret, which soon emerges from the mouth. The spider wets the paw of one leg in it, then the other, and rubs its abdomen with them.
Like all spiders, the silverfish breathes with the help of lung sacs and the entire surface of the body. In order to renew the supply of air in the lung cavity, the spider sticks its abdomen as high as possible above the water so that it is entirely exposed to air. Having ventilated the lungs and hairline abdomen, the silverfish slowly sinks into the water, working like oars with four pairs of legs and carrying away the air supply on threads. While replenishing its air supply, the spider is absolutely defenseless, so in the process of evolution it has improved ways to stay under water as long as possible. The different structure of the hairs covering the abdomen, the ability to care for them and lubricate them with a special secretion, breathing using not only the lungs, but the entire surface - all these are adaptations for the economical consumption of air brought by the spider under water and stored in the form of a bell.
When building a bell, the spider first weaves a web, very similar to the web of ground spiders. As it fills with air, the bell takes on a characteristic shape. Heading to the surface of the water for air for the bell, the spider does not emerge, as it does when it wants to breathe, but crawls up an existing web or aquatic plants, laying the web after itself. When the spider touches the surface of the water, it abruptly changes position, turning 180 degrees with the end of its abdomen facing upward. This point is very important, because with the help of arachnoid warts, the surface tension films of the air bubble surrounding the spider’s body and the surface of the reservoir break through. This is not always successful the first time: he tries in one place, in another, vigorously moves the spider warts, rubs the body near the warts to place the hairs torn off, and the tip of the abdomen is exposed above the water. At this time, the spider’s hind legs take on a very special position: one is bent so that it lies obliquely on the dorsal side of the abdomen, and the other is also on the ventral side. Both legs are pressed tightly against the body and the outside air reaches their curved ends. Then, together with a sharp jerk of the spider’s entire body downwards, its hind legs instantly straighten, their legs cross, and the surface layer of water lying on legs bent, stretches upward along with them. It is as if a certain amount of air is being cut off from the top of the air funnel formed when the spider dives. The air bubble pulls the spider up, so it crawls to the place where the bell is built, clinging to the web. The first bubble is carefully woven into the fabric of the bell's gossamer roof. The spider touches different places on the roof with its arachnoid warts, attaching threads that entangle an air bubble, similar to how they fasten balloon. The second and third bubbles are released under the bell by touching the first. After the third time, the bell is large enough to drag a water donkey in and eat it. But the construction is not finished yet.
The silverfish works, bringing more and more new portions of air, entwining the bell with new layers of web, first from the inside, then from the outside. The spider draws new reinforcing threads to surrounding objects and weaves camouflage plants into the walls.
How does the silver spider feed?
As already mentioned, silverfish lie in wait for prey while sitting in a bell. The hairs on the spider's legs and pedipalps play the role of organs of touch; they use them to feel objects. Despite the fact that the silverfish, like most spiders, has 8 eyes, it sees poorly, but it perfectly perceives all kinds of movements and shocks. It's only worth it small crustacean touch one of the threads of the web, directed in different directions from its bell, as the spider immediately senses this and immediately rushes at the victim. Having returned to the bell with the crustacean in the chelicerae, the spider takes a characteristic pose: it lies on its back and rests its first two pairs of legs against the wall of the dwelling. In this position, the food, supported by the pedipalps, touches the spider’s mouth and the digestive juice does not flow down along it, but remains in the recess of the mouth. Digestion in silverfish, like all spiders, is extraintestinal. The enzymes released outward digest the soft tissues of the victim, which are then absorbed by the spider. The undigested remains are carried out by the spider.
Males of silverfish are somewhat larger than females, which is quite rare among spiders, so mating usually occurs quite peacefully. Before breeding, the male builds a special small bell, closed on all sides, lies on his back in it and, resting his front legs against the wall of the bell, rests. Then he weaves a horizontal ribbon, moving his belly from one wall of the bell to the other. At the same time, separate threads emerge from the holes of the arachnoid warts, which do not stick to each other. The spider then secretes sperm onto these threads and collects them from there with the pedipalp tentacles. After this, he rests again and after a while goes in search of the female.
Reproduction of silver spiders
Mating takes place in the female's summer bell.
The fertilized female begins to lay eggs, for which she rebuilds her summer bell into an egg bell. The female lines the top of the bell with loose cobwebs and lays from 15 to 160 eggs on it. She covers the eggs with cobwebs, and now the bell consists of two chambers - the egg chamber and the vein chamber. The female sits on the eggs with her head down and guards them until the hatched spiders leave the nest. At this time, she does not eat and only occasionally leaves the bell to renew her air supply. In summer, egg development lasts about 10 days. Young spiders emerge from the eggs bald, and therefore can only breathe while inside the mother's bell. The first two molts of young silverfish also take place here, after which the spiders leave their mother’s bell and move on to independent life. The mother immediately ceases to recognize them and, on occasion, may eat them. Spiders grow quickly and with good nutrition After three months they reach their maximum size: females 12 millimeters, males 18 millimeters.
The growth of spiders is associated with molting, for which a special bell is built, which is called a molting bell. The molting process begins with the rupture of the old integument on the cephalothorax, then on the abdomen. After this, the spider pulls its legs out of the old skin, like from boots. The exhausted soft spider lies on its back and rests. Then he gets up, feels his old skin and sits down on it, trembling slightly as he does so. After molting, the spider remains inside the bell for some time until its covers harden.
The lifespan of a water spider is about 18 months. Silverfish overwinter in different stages: there are fewer adult males in the winter than females; most of all among wintering young spiders. Sometimes late egg cocoons overwinter together with the females. For wintering, a special wintering bell is built, especially durable and strong. The composition of its walls, in addition to the usual web, includes a special glassy mass. Sometimes spiders overwinter in empty mollusk shells. There they also weave a cobweb cocoon, but less dense. Shells with spiders often freeze into the ice, but silverfish can easily withstand such a harsh winter. In the spring, the shells and wintering bells of spiders are carried away by the flood, which serves as an adaptation for their settlement.
Ours is connected with water ordinary spider dolomedes, which lives in coastal vegetation, but can very deftly glide along the surface of the water, like water strider bugs. Sitting on the leaves of water lilies, dolomedes lies in wait for aquatic insects, mollusks, and sometimes even tadpoles and fish fry, after which it deftly dives into the water. However, dolomedes pick up most of their prey from the surface of the water. How do spiders notice an insect that has fallen into the water? It turns out that dolomedes reacts to waves diverging along the surface of the water. The spider responds to single blows on the water only in 15% of cases, but with prolonged blows it determines not only the direction, but even the distance to the source of the wave. Spiders seem to feel the waves with their legs, measuring their amplitude and using it to determine the distance to the victim. Dolomedes builds a cocoon for laying eggs on semi-aquatic plants.
The silverback spider is a famous representative of the arachnid order, gaining popularity as the only spider that lives underwater in an underwater nest - a dome. How does a spider fill its house, woven from a web, and how does a brave “scuba diver” live, reproduce, hunt and hibernate under a layer of water?
Silver spider or water spider
Spiders are the first representatives of arthropods to colonize land. They live in almost all climatic zones and parts of the world, even in Antarctica. The only one of its kind - the silver spider has returned for the second time to aquatic environment habitat and took a place in the food chain fauna of reservoirs with quiet and calm currents. The water spider is no different from other spiders; it has adapted to life in water, but its respiratory organs remain the same as those of all arachnids - these are the lungs, trachea and spiracles (small holes at the edges of the abdomen through which the spider breathes).
How a silverback spider builds an underwater nest
The water spider, like all arachnids, weaves a web, choosing secluded places under snags, stones, and between the stems of aquatic plants. The web serves building material, from which the spider builds a castle, filling it atmospheric air. An experienced diving spider floats to the surface of the water, turns over sharply, exposing its abdomen with spiracles, through which air enters the trachea. The body of the spider is covered with small villi, between which air bubbles are easily located; the spider brings them to its nest and shakes them off with the help of its paws. 5-6 ascents to the surface are enough and the dome of web and air is ready.
The role of the air capsule in nutrition and hunting
The air dome-nest is located with the hole down. The silver spider, having hidden its abdomen in an air capsule (it breathes through spiracles in the abdomen), leaves the cephalothorax and chelicerae on the surface, acting as a jaw, and hunts for fry of fish and crustaceans. The spider has 8 eyes, but they are poorly developed; it hunts with the help of touch, waiting for the victim entangled in its intricate web. Having received a “call” on the signal thread, the spider digs into it with its chelicerae and drags it under the arches of the dome.
Air chamber-socket
The air house is the place where the female lays eggs and guards the cocoon until the offspring are released. She does not eat and only rises to the surface of the reservoir for a portion of air. The male is larger than the female and they coexist in the same nest, which is not typical for arachnids. The female lays eggs in the summer, and by autumn the young spiders are already building their nest.
Underwater capsule - a place for shelter and wintering
The silver spider can survive unfavourable conditions in your capsule. During the daytime he hides and at night he goes out hunting. By winter, the spider weaves a strong web, closes the opening of the capsule and waits out the cold in a state of suspended animation. The capsule breaks off during ice drift and carries the spider over a long distance with the current, facilitating the settlement and conquest of new habitats. The spider often uses mollusk shells for wintering.
The silver spider is a very useful arachnid. It eats mosquito larvae, the remains of insects that have fallen into bodies of water, and also conducts natural selection using weak and sick fish fry as food. The silver spider is listed in the Red Book as an endangered species.
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