Silver water spider - photo and description

Kirill Mikhailov, Candidate of Biological Sciences, Zoological Museum of Moscow State University. M. V. Lomonosova

Prokopiy Nogovitsyn,
Oysk secondary school named after.
A. V. Dmitrieva (Oy village, Khangalassky ulus, Republic of Sakha (Yakutia)) “Nature” No. 10, 2017

Female silver spider. Photo by J. Lissner (Denmark)

As befits predatory animals, the vast majority of spiders live alone, joining in pairs only for the breeding season. Colonial forms are known for literally a few dozen of the more than 45 thousand species described to date. Most colonial forms live in tropical countries. Coloniality manifests itself primarily in the cohabitation of large groups, which, as a rule, still eat separately. Combined hunting and feeding on prey is observed only in a few species; The most studied in this regard is the small spider Anelosimus eximius

(family Theridiidae), living in South America.

Two hypotheses have been put forward for the origin of coloniality in spiders. One of them involves the accumulation and cooperation of adult individuals around an abundant food resource, when there is enough food for everyone and there are no special reasons for showing aggression towards neighbors. According to the second hypothesis, the offspring of one female, growing up, do not disperse, but continue to live together. Perhaps both of these hypotheses apply to different species of colonial spiders.

Colonial spiders do not live in Russia and neighboring countries. But in the southern regions, accumulations of orb-weaving spiders (family Araneidae) on the coasts of water bodies have been repeatedly noted. They are most likely associated with the mass production of some small flying insects that these spiders feed on. On the coast of of Araneus pallasi described in Balkhash

[], and on the shores of the Caspian Sea, north of Krasnovodsk, -
Larinioides folium
[].
In the summer of 2012, in the city of Yeisk on the coast of the Sea of Azov, K. G. Mikhailov was able to observe a concentration of L. folium
on vegetation and walls of buildings located on the Yeisk Spit in close proximity to the sea.
This concentration was associated with the annual mass flight of the bell mosquito ( Chironomus plumosus
, family Chironomidae). The sanatorium staff barely had time to sweep away the cobwebs so as not to scare the vacationers...

Young silverfish, lake. Balaton. Photo by W. Pflieger (Germany)

However, there are spiders whose mass concentrations are difficult to imagine, especially on land. This is the silverback water spider ( Argyroneta aquatica

), the only spider whose entire life cycle takes place within a fresh body of water. Silverfish are an example of the secondary return of an arachnid to the aquatic environment, which is not very typical for representatives of this class. Of the other arachnids, only water mites, which are found in both fresh and salt waters, have switched to permanent residence in water. The silverfish is widespread in the Northern Hemisphere, in Russia and neighboring countries it is found everywhere, and has even been recorded in a few reservoirs in the desert zone of Central Asia. In some countries, silverfish are rare; for example, in Japan this species was included in the Red Book back in 1995. Let us briefly describe the biology of this wonderful spider [, ].

How do they swim?

Almost all spiders are terrestrial predators; the silverback is a pleasant exception to the rule.
It's all about the unique anatomy. The abdomen, covered with hairs and special fat, has the ability to accumulate air bubbles. As a result, a kind of air cushion is formed between the body and the hairs. Due to this, the silverfish feels great under water. She needs to come up regularly to replenish her air. Fat is a secretion of spider glands that has changed in composition. There is a funny feature that allows you to distinguish the gender of the silverback spider. To do this, you need to look at the bubble around the body: the male’s upper abdomen is free of air. The female has a bubble around her entire body and swims upside down. Males often swim horizontally and use their legs as oars. The water spider is able to cover a distance of two centimeters in a minute. This is a decent distance for such a baby.

3The 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.

Biology of silverfish

The silverfish, like all spiders, breathes atmospheric air. The respiratory system of spiders is dual in nature: both the lungs and the developed tracheal system work. But in a water spider, the lungs are inactive and the trachea functions primarily. Water-repellent hairs on the spider's abdomen retain a layer of air, which the spider breathes underwater. It was because of the silvery underwater bubble around the abdomen that the spider received its name, both Latin and Russian. To live permanently underwater, the silverfish builds an underwater bell from spider threads, which holds a bubble of atmospheric air. The threads of the web are attached to the surrounding underwater vegetation. The carbon dioxide released by the spider dissolves in the surrounding water, and oxygen must be constantly supplied from the surface of the water. To move the air bubble from the abdomen to the bell, the spider uses the fourth pair of legs. The silverfish needs underwater bells for living in the warm season, mating and breeding, eating prey and wintering. The bell for wintering is the most durable; its walls are sometimes opaque, unlike the walls of the summer dwelling, which is built less securely and is often additionally attached to the surrounding algae. The silverfish is capable of overwintering in thick ice, freezing there together with a bell or other shelter, such as an empty shell of a freshwater mollusk.

It has long been known that the bell of the silverfish serves as a kind of “physical gill”: oxygen penetrates there from the water column (see one of the latest experimental works []). For this reason, the spider can sit inside the bell for a whole day without rising to the surface of the water for a new air bubble. Frequent mechanical filling of the bell is necessary primarily in oxygen-poor water and for small bubbles.

Serebryanka lives in stagnant and low-flowing reservoirs. She catches prey using web threads located next to the bell. These threads primarily perform a signaling function. The structure of the web is quite primitive and is a deviating version of the funnel-shaped web, which is built by its land relatives from the families Agelenidae, Cybaeidae and some others. (Previously, this entire group of spiders was united in the family Agelenidae, now they talk about the “Agelenoid complex” of families.) Below we will describe , what kind of buildings the silverfish is capable of building on the shore.

Spiders of the agelenoid complex, which include the silverfish, are characterized by a phenomenon that is atypical for the order of spiders as a whole: the males here are slightly larger than the females. In the vast majority of spider families, we observe just the opposite phenomenon: females are larger than males. Sometimes they even talk about dwarfism in males and gigantism in females (for example, in tropical orb-weaving spiders of the genus Nephila

). A male interested in mating builds his bell next to the female's. The relationship between the sexes of the water spider is quite aggressive. If mating is successful, the male remains in the female's bell for some time, sometimes up to several hours, waiting for the female to begin building an egg cocoon. The rest of the time, male and female silverfish live separately, each in their own bell. Males, as usual, are more active and spend more time outside their home.

At some point (between mid-spring and late summer), the female silverfish lays 70 to 130 eggs in an egg cocoon, from which larvae hatch and live with the mother for 2-4 weeks, until the fourth molt. After this, the young spiders begin to live independently, starting to build their own small “bells”.

The water spider hunts underwater, sitting in its bell, as if in ambush. Having caught the prey, the spider returns to the bell, where the victim is sucked out and extraintestinal digestion, impossible in the water column, occurs. The most active hunting occurs at night.

Varieties

There are several types of water spiders.

Hydrachna cruenta Mull

This species is sometimes called the red spider water mite.

The arthropod lives in swampy bodies of water with warm, standing water. The spider looks like a small red ball and moves quite quickly across the surface of the water. It feeds on larvae and small crustaceans, but quite often it itself becomes prey to predatory insects or fish.

Red spiders lay eggs on the inner parts of the leaves of aquatic plants, connecting the eggs with each other with an adhesive solution.

The young are born with six legs. At first, young individuals parasitize on beetles and bedbugs, clinging to them with their proboscis, but soon they go into aquatic burrows, where they pupate and turn into full-fledged spiders.

Dolomedes fimbriatus L

Hunter spider. This species does not live in water, but next to it or on its surface.

The arthropod has a gray-brown color with white or yellow running along the sides of the body.

stripe. In the middle of the body you can see two rows of light gray dots, the chest part is predominantly yellow, and the abdomen is gray. The female huntsman spider reaches 2.5 cm in size, the male is several times smaller.

The huntsman spider is remarkable because it builds rafts. Due to the lack of the ability to move along the water surface, the arthropod collects leaves and sticks floating in the water and binds them with a web. Having discovered prey, the spider quickly gets to it on its floating island, drags the victim onto the raft and eats it there.

Females lay eggs on plants growing along the banks of a reservoir, cover them with a cocoon of cobwebs and guard them until the offspring appear.

Clubionafallax

The silver spider (or dropsy) is the most common aquatic species in Russia.

spiders This population has adapted to living underwater, where spiders build several types of oxygen-filled domes that have different purposes:

summer (for shelter, eating food and mating);
sperm (for sperm collection);
ovarian (for laying eggs and producing offspring);
for molting;
wintering

To fill the nest with air, the spider has to follow it to the surface at least 80 times.

Males are gray-green or black in color and reach 15 mm in size. Females are lighter in color and 2–3 mm smaller than their partners.

What does it eat?

Like all representatives of arachnids, silverfish are predatory animals. They build traps that are located under water to catch prey. The web serves to catch small animals while the owner waits in the dome. By the vibrations of the webs, the silverfish determines the appearance of the victim.

Then the dropsy acts like all spiders - it injects poison, then saliva. Waits for the food to soften and has lunch. If there is no desire to eat, the prey is taken into the dome and hung in reserve in the web.

Dropsy's food consists of underwater and terrestrial small inhabitants. The female's prey is often her own children who leave the nest.

Small crustaceans

The silverfish spends most of its life in water. Small crustaceans are the spider’s usual diet. The most favorite types of food include water donkeys, small crustaceans measuring 1-2 millimeters in size.

Fry are also often caught in silverfish nets, which can reduce the population of some fish species.

Mosquitoes

Mosquito larvae and the insects themselves, which live in abundance near bodies of water, make up a significant part of the silverfish’s diet.

flies

Ubiquitous flies of various species and their larvae often end up in webs and become food for silver spiders.

Notes

Annotated list of rare and endangered species of invertebrate animals, specially protected within Russia // 2003* Russia* Red List of Specially Protected Rare and Endangered Animals and Plants. (2nd issue). Part 2. Invertebrate animals (Red Book Bulletin, 2/2004 (2008)) / rep. ed. V. E. Prisyazhnyuk. - M.: Red Book Laboratory of the All-Russian Research Institute for Nature Conservation, 2004 (2008). - P. 118. - 512 p. — ISBN 978-5-9243-0158-7 [https://ashipunov.info/shipunov/school/books/krasnyj_spisok_rossii_2008_2_besp.pdf Full text]
Lange A. B. Subtype Chelicerata // Animal Life. Volume 3. Arthropods: trilobites, chelicerates, trachea-breathers. Onychophora / edited by M. S. Gilyarov, F. N. Pravdin, ch. ed. V. E. Sokolov. — 2nd ed., revised. - M.: Education, 1984. - P. 68. - 463 p. — 300,000 copies.
I. I. Akimushkin.
Patent for a diving bell // Insects. Spiders. Pets. — 4th ed. - M.: Mysl, 1995. - T. 3. - P. 219-220. - (Animal world). — 15,000 copies. — ISBN 5-244-00806-4.
Microcosmos (film, 1996), 40 minutes

What is interesting about the silver spider?

The water spider managed to arrange itself in such a way that it lives in the air even under water. 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 spaced, 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. The chelicerae begin to work, stimulating the secretion of a clear secretion, which soon appears 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 using 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 abdominal hair, the silverfish slowly lowers into the water, working like oars with four pairs of legs and carrying away the supply of air on the hairs. 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 the bent legs is pulled up 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 various places on the roof with its web warts, attaching threads that entangle an air bubble, similar to how a balloon is secured. 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.

PORTRAIT OF A HERO

In appearance, the silverfish is not easy to distinguish from its land-based relatives. The spider's cephalothorax is dark brown, with black lines and spots, and almost naked. It has eight eyes. On the dorsal side of the brown abdomen, covered with velvety hairs, two rows of depressed points are noticeable. Young spiders are yellowish-gray, old ones are much darker, sometimes almost black. The male is larger than the female - a rare occurrence among spiders. Perhaps this is why he remains alive after mating and lives peacefully side by side with his wife. In addition to its smaller size, the female is distinguished by a light gray coloration of the rear part of the body, and the male’s abdomen is more elongated.

Where does the Brazilian wandering spider live?

Photo: Dangerous Brazilian wandering spider

The main habitat of this species is America. Moreover, most often these arthropods are found in the tropical forests of Central and South America. Representatives of this species can also be found in Brazil and northern Argentina, Venezuela, Peru and Havana.

Spiders are thermophilic; the main habitat of these arthropods is the tropics and jungle. There they are placed on the crowns of trees. Spiders do not build shelters or burrows for themselves; they constantly move from one habitat to another in search of food.

In Brazil, spiders of this species live everywhere, perhaps only in the northern part of the country. Both in Brazil and in America, spiders can crawl into houses, which terribly scare the local population.

They love warm and humid tropical climates. Spiders of this species do not live in Russia due to the climate. However, they can be found accidentally brought from warm countries in boxes with tropical fruits, or by spider lovers for breeding them in a terrarium.

In recent years, this dangerous animal is increasingly being kept at home as pets. At home, they can live all over the world, but keeping them is not recommended due to the extreme danger of this species. Spiders also don’t live well in captivity, so you need to think carefully before getting such a pet.

Now you know where the Brazilian wandering spider lives. Let's see what he eats.

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.

Associated with water is our common dolomedes spider, 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.

Features of character and lifestyle

Photo: Funnel-web water spider

The silverfish goes out hunting at night and rests most of the day. Females rarely leave the nest except to replenish their air supply - perhaps for hunting. But even she is often led passively, barely leaning out of the nest, and waiting until some prey is nearby.

Males are much more active and can move away from the nest at a distance of up to ten meters in search of food. Although most often they also remain within a meter or two, under the protection of their networks, ready to react to signals emanating from them at any moment.

They can overwinter either in cocoons, which they weave themselves, or in empty mollusk shells. They prepare their silverfish for winter in a very interesting way: they draw air inside until they float, then attach them to the duckweed and crawl inside the shell.

When the shell is ready, you can go into hibernation - it will be warm enough inside for the water spider to survive even in the most severe cold. Such floating shells can be seen in the autumn months - this is a sure sign that silverfish live in the reservoir, since without their help the shells rarely float to the surface.

When winter comes, the duckweed falls off, and the shell goes to the bottom along with it, but thanks to the dense web, the water does not flood it, so the spider successfully overwinters. In the spring, the plant floats up, and with it the shell; sensing the warmth, the silverfish wakes up and climbs out.

If the summer is dry and the reservoir is dry, then water spiders simply spin cocoons and hide in them from the heat, waiting until they find themselves in the water again. Or they can fly away on a web to other lands, in search of a larger body of water that has never dried up. In any case, they are not in danger of death in such situations.

Description of the species

The water spider differs little from its fellows. Like all arthropods, it has an abdomen and cephalothorax, which are clearly divided into segments. The color is dark brown, with lines and spots. The limbs and abdomen are covered with special hairs, which give the pack a silvery tint. The cephalothorax is naked, with eight ocelli located on it. They see poorly. There are two rows of barely noticeable dots on the abdomen. The color becomes richer with age. Young individuals are gray-yellow, old ones are almost black. The silver spider has interesting features:

The male is larger than the female (for this family it’s usually the other way around).
After mating, the female does not kill the male.
The male's abdomen is slightly elongated.
The female has a light gray color on the lower part of the abdomen.

The lungs and trachea open on the lower part of the abdomen. On the upper part of the cephalothorax there are two pairs of jaws. The size of the male is about 1.5 cm. Females are slightly smaller in length.

Features of keeping at home

Sometimes this spider is kept as an exotic pet. Such a pet is interesting because it is active during the day (especially the male), and water spiders are entertaining to watch.

It is recommended to use an aquarium of about 5 liters per adult. To weave a bell, a water spider will need a base of branches or aquatic plants. Thanks to this, you can determine the place where the spider will build a nest. Some of the branches must come out of the water so that the silver spider has the opportunity to get out onto land.

You can feed the arachnid with small fish, gammarus, water donkeys and various insects. It is acceptable to keep females and males in the same aquarium, but it is important to consider that if the spiders do not have enough food, they will begin to show aggression towards each other. Also, juveniles should not be kept together with adults.

Sex differences in water spiders

The silverback spider has pronounced sexual dimorphism: males are always larger than females (this phenomenon is quite rare in arachnids), so the mating process occurs quite peacefully, the individuals remain alive and healthy.

One clutch can contain from 15 to 160 eggs, which the female lays in her dome, separating it from the main living area with a web. Under favorable conditions, the spiders hatch after 10 days; inside the mother's bell, the young spend their first two molts.

An interesting fact - after hatching little spiderlings, the mother may not recognize her brood and, on occasion, eat it. Water spiders live for about one and a half years; the wintering period can fall on any part of the life cycle.

During wintering, spiders build especially strong and durable winter bells. In addition to the usual thread and camouflage, it includes a special glassy mass. After wintering, the shelters of spiders are carried over long distances by the flood, thanks to which silver spiders are widely dispersed.

Social structure and reproduction

Photo: Water spider in Russia

They live in groups, although each individual lives in its own nest at a short distance from the others. They do not conflict with each other, but in rare cases, cases of cannibalism are known. This is also possible when kept in captivity, if there are too many silverfish living in one aquarium.

Both individuals of the same sex and those of different sexes can live nearby, since female water spiders are not inclined to eat males. Spiders often live in pairs, placing nests in close proximity to each other. Females reproduce in the nest.

At the onset of warm spring, the female bearing eggs lays a clutch in her nest: usually there are about 30-40 eggs, sometimes much more - over one and a half hundred. She separates the clutch from the rest of the nest with a partition and then protects it from intrusion, practically without leaving it.

After a few weeks, spiderlings emerge from the eggs - they are developed in the same way as adults, only smaller. The mother spider continues to take care of them until they leave her - this happens quickly, the spiders grow up in just two to three weeks. After this, they build their own nest, most often in the same body of water.

Although sometimes they can travel, for example, if there are already a lot of silverfish where they were born. Then they climb onto the plant, let out a thread and fly on it with the wind until they reach another body of water - and if that doesn’t come, they can fly further.

Interesting fact: When kept in captivity, small spiders must be moved out, because otherwise there will be too little space in it, and they may even be eaten by their own mother. This does not happen under natural conditions.

Description of the arthropod

Appearance

It has 8 eyes, 2 of which are on top, 2 on the sides, and the remaining 4 in a single row are located in front. Only 2 eyes located on top are fully functional; the remaining eyes are simple. Therefore, the spider moves using its front legs, relying on motion sensors.

Reproduction

The mating process among agelenids is quite simple. It all begins with courtship, during which the male, having discovered the female’s web, begins to tap monotonously on it, thereby putting the female in a state of trance. Then the spider takes the unresisting female, indifferent to everything that is happening, to a place convenient for him and mates. After this, the male and female live together for several weeks.

Nutrition

For food, all known species of funnel-web spiders hunt various arthropods. These are mainly soft chitinized arthropods - small spiders, flies, mosquitoes, leafhoppers. But individuals are also often found feeding on such potentially dangerous and well-protected insects as large Orthoptera, ants, beetles and even honey bees.

Habitats

Representatives of the family Agelenidae can be found in northwestern Europe. Tegenaria domestica

is the most common species of this insect, which can be found throughout the region. The habitat of the species Tegenaria agrestis, Agelenopsis, Allagelena, Alloclubionoides, Tegecoelotes was found in the south of the Far East; Agelena Paracoelotes - in Siberia and the south of the Far East; Iwogumoa interuna - on Sakhalin, Moneron and the Southern Kuril Islands.

Usually funnel-web spiders can be found near people's homes or in the grass. But their appearance is especially frequent in the autumn, during the mating period, when the male is looking for a female on the walls of buildings.

What does a silver spider and its underwater home look like?

Representatives of this type of arachnid have a brown abdomen, as well as a black cephalothorax and limbs, although at first glance at the silverfish it may seem that they have a “mirror” color - this illusion arises due to the fact that light rays are refracted when they hit air bubbles that linger in many small hairs that cover the body of the spider.

The spider breathes air; if you watch its home for some time, you will notice how it regularly emerges to the surface, performing air exchange. To maintain water-repellent properties, the spider lubricates its abdomen with a secretion secreted by chelicerae.

It is easy to distinguish a female from a male by the shape of the abdomen: females have a rounded abdomen, and therefore the air dome is spherical, while males have a more elongated abdomen, so the air dome encircling the abdomen is heart-shaped.

The density of the hairs does not allow moisture to penetrate deeply, and in order for the hairs to perform their function of capturing air bubbles, spiders have to clean them daily with their paws.

In nature it is not easy to find silverfish and their underwater habitat, but if you find it, you will not confuse it with anything else. The first thing you can see is a magnificent air bell, fixed by a web between underwater plants, in which the silver spider sits. In the water column you can see an air bubble, inside of which the spider’s abdomen is located, and the cephalothorax and limbs are outside.

The construction of an underwater bell begins with weaving a web at depth, then the silverfish rises to the surface, captures air bubbles with its hairs and drags them under the net; after several surfacings, the spider’s home takes on a characteristic shape and becomes easily recognizable.

After this, the spider strengthens the structure several more times with its web outside and inside, and also brings additional air bubbles. After construction is completed, the spider begins to camouflage its underwater home - covering it with the remains of aquatic plants.

Diet of the silver spider

The spider's home is its observation post, where it lies in wait for its prey. The favorite delicacy of arthropods is water donkeys.

Despite the presence of eight eyes, vision is not the main sense organ; the silverfish perfectly perceives the movement of prey in the water column thanks to the threads of the web, which support the air dome in the water column and serve as excellent indicators of the approach of prey.

As soon as the spider senses the movement of the water donkey, it immediately rushes towards the prey; if the throw is successful, the spider captures the victim and carries it to its underwater house.

Like most representatives of arachnids, silverfish have extraintestinal digestion: they inject digestive juices into the body of the victim, active digestion of the contents occurs, and then the spider absorbs all the digested substances.

Body size and structure

The appearance of dropsy is quite classic - the body consists of two parts. There is a deep section between the cephalothorax and abdomen.

The body of young spiders is lighter in color (yellow-brown, greenish-gray) than that of adults and old ones.

Body structure features:

The cephalothorax is rounded, the head is convex, slightly narrowed.
There are 8 pairs of eyes, despite this vision is weak; even a few centimeters away, the silver spider cannot distinguish objects.
There are 2 pairs of jaws on the head, one of them has sharp edges (chelicerae) and a poisonous gland. With the help of the secretion of this gland, the spider immobilizes and kills prey.
The legs have hairs with which the spider feels objects. They play the role of organs of touch.
The scutellum is shaped like a heart; underneath it are the bases of 4 pairs of legs. In males, the front legs are longer than the hind legs.
The abdomen is not dissected. The surface is covered with bristles or hairs. Their density is very high - about 1000 per square millimeter. These hairs have different shapes and lengths. They serve to hold air around the body.

The structure and arrangement of hairs in males and females is different.
The male has no hairs on part of his back. Because of this, the air dome of spiders is different; the female can be distinguished from the male by the shape of the bell around the body. Although most of the silver spider's life is spent in water, it breathes atmospheric air. Underwater existence is ensured by the construction of a cozy nest, similar to a vessel with air, and thin bristles that are not wetted by water.

Silverfish constantly rub their hairs with their paws, clearing them of impurities so that they retain air better. To do this, they suck their paws, secreting a special secretion that they use to treat the hairs on their body.

This is the main activity of the spider in the air dome when it is not waiting for prey.

The size of female silverfish is 11-12 millimeters, males – 14-18 millimeters. Female dropsy are small and not aggressive. They do not eat their males after fertilization, like other spiders. They get along well in the neighborhood - males usually build a house near the nests of females, so as not to spend a long time looking for a partner for reproduction.

Population and species status

Photo: Water spider

Water spiders inhabit vast areas of Eurasia, and they can be found in almost every body of water, often in quite large quantities. As a result, this species is considered one of the least endangered species - so far it clearly does not have any problems with the population size, although calculations are not being carried out.

Of course, the deterioration of the environment in many reservoirs could not but affect all the living creatures living in them, however, silverfish suffer the least from this. To a lesser extent, but this can also be attributed to their prey, due to the disappearance of which they could also be forced to leave their habitats - various small insects, they are also not so easy to remove.

Thus, we can conclude that of all highly organized living organisms, extinction threatens the majority of spiders, including silver spiders, perhaps least of all - these are well-adapted creatures capable of surviving even in extreme conditions.

Moreover, they are unpretentious: they only need to be fed and the water changed from time to time. It is also necessary to close the container with them, otherwise the spider will sooner or later go on a journey through your house in search of a new habitat, and maybe, what the hell, fly out into the street or be accidentally crushed.

The water spider, even though it is poisonous, is a harmless creature for people if not touched. It is unique in that it weaves its nets right in the water and constantly lives and hunts in it, even though it does not have a breathing apparatus adapted for underwater life. It is also interesting because it can equip empty shells for hibernation.

Water spider: photo of appearance and danger of bite for humans

This unusual species of spider lives throughout the vast territory of Eurasia, from Portugal to Japan.
It is unusual because it is the only spider in the world whose habitat is water. Water spider - it received this name due to its peculiarity.

It can live and move on land, but does so extremely rarely.

It lives in ponds, coastal waters of lakes - in standing waters. It is extremely rare to find it in small rivers or streams with a weak current.

Is there any benefit or danger to humans?

Each insect or animal brings certain benefits. Silverfish destroys larvae and adult insects. Mosquitoes, flies and other flying pests can become dinner for silverfish. They often eat weak or sick fry, helping to form natural selection. They are poisonous and this protects them from the appearance of natural enemies.

https://youtube.com/watch?v=MUniPHc5VmI

The silverfish rarely attacks first, since it does not have developed aggression. However, when threatened, it can bite hard. Despite the fact that the venom is not fatal to humans, the bite can cause a lot of trouble. The wound aches, the pain intensifies, and sometimes numbness appears. But after a few days, all pain disappears. Some species of water spider are on the verge of extinction and are listed in the Red Book, so there is no need to destroy them because of personal hostility.

Why is a water spider dangerous for humans?

A water spider will not purposefully attack a person, but it can attack in case of danger. In most cases, the silver spider will try to escape; it extremely rarely shows aggression and bites a person. And if it lives in captivity, it reacts to the presence of people quite calmly.

Spider venom can cause an allergic reaction, especially in children, pregnant women and people with weak immune systems. The list of main symptoms of a bite includes: slight swelling, redness of the skin, burning.

Allergies include nausea, vomiting, dizziness, fever, weakness, and headache. Symptoms in most cases go away on their own after a few days, but despite this, it is recommended to take antihistamines.

The water spider can harm agricultural sectors such as fish farming. By eating fry, representatives of this species significantly reduce the number of fish. But, as a rule, weak fry become victims of the water spider, i.e., in essence, the spider plays the role of a natural breeder.

What does a water spider look like and is it dangerous for humans - interesting facts about silver spiders, varieties