Water spider. Water spider: photo of appearance and danger of bite for humans. How does the silver spider live and what does it eat?

Water spider (Argyroneta aquatica)

– a common species of spider in Europe from the family Cybaeidae. An exceptional creature, he most spends his life under water. It is safe for humans, but its bite is very painful. In winter, the water spider hides in a cocoon. Females and males of this species are almost the same size (approximately 12-15 mm).

By appearance The water spider is almost no different from other spiders. Its body is divided into a cephalothorax and abdomen, separated by a deep interception. Both parts of the body are unarticulated. Four pairs of long, jointed legs sit on the chest. On the cephalothorax, in the front part, we notice eight pairs of small shiny eyes. There are two pairs of jaws: the first pair is called chelicerae and is used for grasping and killing prey; it is claw-shaped and equipped with a poisonous gland; the second pair, called pedipalps, plays the role of jaw tentacles.
In most spiders, males are smaller than females. In silverfish, males and females are almost the same size; Often you come across a large variety of males, which are even much larger than females. Young animals are yellowish-gray or yellow-brown in color, old ones are much darker than young ones, sometimes almost black. Females differ from males, except for size, in the light gray color of the rear part of the body. In addition, males have a more elongated abdomen. Most often, the water spider is found in standing or slowly flowing waters rich in vegetation.
Movements. Having been snatched from its native element by a net, the water spider tries to escape and immediately reveals itself to the observer. On land, it moves very quickly and dexterously, no worse than many land spiders. But at the same time, it swims quite well, using all its legs like oars.
Breathes silverfish, like other spiders, atmospheric air, which captures, rising to the surface of the reservoir. When immersed in water, part of the air is carried along with it in the form of an air film that envelops the body. This phenomenon is usually explained by the fact that the spider’s body is covered with fine hairs that are not wetted by water. However, the problem here, apparently, is not the hairs, but the thin mesh of cobwebs with which the spider surrounds its body. With the help of this mesh, it captures an air bubble when immersed under water.
Having placed the caught spider in a vessel with water, you can immediately observe a very beautiful sight during the excursion: the air enveloping the abdomen glitters under the water like silver (hence the name - silverfish).
It is interesting that the air bubble covers the body of the male and the body of the female differently: in the female, air surrounds the entire abdomen and part of the cephalothorax, while in the male the upper part of the abdomen remains free of air. Because of this, the air bubble of the male is smaller in volume, not so much pulls him upward and gives him the opportunity to make more dexterous movements in the water and swim not only head down, like females swim, but also holding horizontally (according to V.A. Wagner).
When breathing air is carried into the pulmonary sacs, which are located on the underside of the abdomen and open with paired respiratory openings. The silverfish has only one pair of lungs, which is why it is classified as a group of two-lunged spiders (Dipneumones). In addition, the silverfish also has a system of tracheal tubes, which open with two holes on the lower part of the abdomen.
Feeds silverfish with various small aquatic animals, for example, insect larvae, water donkeys, etc. When attacking prey, it envelops it in a web and then sucks it out; at the same time, it uses its claw-shaped chelicerae, with which it digs into the victim, poisoning it with the secretion of its poisonous glands.
Construction of a home is a remarkable feature of the water spider. It builds underwater, from the secretions of its arachnoid glands, air-filled dwellings that look like a thimble or a bell. The arachnoid substance necessary for construction is secreted, like in other spiders, from spinning glands that open on special papillae, which, among two pairs, are located at the posterior end of the abdomen and are called arachnoid warts. The sticky liquid they release quickly hardens in air and in water, forming strong transparent threads.
The buildings it is difficult to detect spiders on the excursion itself. Having, however, been planted in an aquarium, the spider quite soon arranges an airy home for itself in captivity, giving the opportunity to conveniently observe the techniques of its construction. First of all, it arranges a braid underwater from rare threads of the web, attaching it to aquatic plants or other objects. Then the spider begins to pull air under this network, capturing it from the surface. The air held under water by the spider web mechanically lifts it and forms a dome shape. The resulting formation is covered with new threads of the web; the end result is a transparent, air-filled structure reaching the size of a pigeon egg. The bell serves as a reliable underwater shelter for the spider; here he rests, here he eats caught prey, etc.
If the spider is healthy and well-fed, then its bell is large and well filled with air. In starving, weak animals, the bell gradually collapses. Sick spiders gradually lose even the ability to envelop their bodies with air, begin to become wet with water and drown.
Wintering spiders is an interesting phenomenon, which can be partly covered by a tour. For the winter, spiders make cocoons underwater, in which they hibernate. But sometimes they overwinter in the empty shells of mollusks (ponds, coils, etc.). Having found such a shell, the spider forces air into it until it floats to the surface. The shell is attached by spider threads to aquatic plants (duckweed) floating on the surface. The spider hides in the shell and closes its opening with plant debris held together by cobwebs.
Such floating shell-cocoons can be seen in the fall on the surface of reservoirs. It is enough to open the shell to discover its inhabitant. V.A. Wagner says that, having once examined a hundred such shells collected from ponds in the vicinity of Moscow, he only did not find a spider sitting inside in two of them.
With the onset of cold weather, aquatic plants sink to the bottom of the reservoir and, along with them, submerge the silverfish in its shell. In the spring, the duckweed emerges, and the shelter of the overwintered spider is again brought to the surface, freeing the captive.
Reproduce water spiders, like others, have eggs. The eggs are laid in an underwater cocoon, which is similar in construction to an ordinary bell, but its walls are much denser. The eggs are laid at the top of the bell and secured with spider threads. Young spiders emerging from eggs soon begin to build small underwater lairs for themselves, resembling adult spiders.

Description

The male, which is larger than the female (this prevents cannibalism of females), reaches 15 mm in length, the female up to 12; almost naked cephalothorax of a brownish color, turning into blackish, with black lines and spots; the abdomen is brown, covered with many velvety hairs and has two rows of depressed points on the dorsal side.

When a silverfish is immersed in water, the hairs of the abdomen, covered with a special fatty substance, are not wetted; air is retained between them (as it is not displaced due to the forces of surface tension of water) and therefore it appears silver under water. This layer of air allows the silverfish to remain under water for a very long time; he occasionally rises to its surface to renew his supply of air. The water spider is often found in standing or slow-moving waters.

The water spider feeds on various small animals that become entangled in the threads of its underwater web, or which it catches while swimming in the water. He sometimes hangs the excess prey he catches in his nest.

Nest

The silverfish makes a bell-shaped or funnel-shaped nest underwater from cobwebs, attaching it to various underwater objects. The spider fills the nest, open at the bottom and reaching the size of a hazelnut, with air and uses it as a kind of diving bell.

To fill the nest with air, the water spider rises to the surface of the water and exposes the tip of its abdomen, pushing apart the arachnoid warts, then quickly dives and takes with it, in addition to the layer of air covering the entire abdomen, also an air bubble at the end of it. Having reached the nest, the spider separates the bubble from the abdomen with its hind legs and transfers it to its building. Male silverfish sometimes climb into empty snail shells and hibernate in them, plugging the entrance with cobwebs.

The male and female silverfish live side by side in nests, which is not typical for spiders.

Reproduction

The eggs are laid in a cocoon of web containing air and placed close to the nest or in the nest itself and carefully guarded by the female.

Literature

N. M. Knipovich// Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional) - St. Petersburg. , 1890-1907.

Categories:

Animals in alphabetical order
Araneomorph spiders
Animals described in 1757
Arachnids of Europe
Arachnids of Asia
Arachnids of Africa

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Books

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Water spider or silver spider

Family representative Argyronetidae - Argyroneta aquatica the only spider that has perfectly adapted to underwater existence. It is most often found in stagnant or slow-moving waters rich in vegetation.

Silver spiders adapt well to aquarium conditions. They can be kept in any vessels - and 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.

In 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).

The silverfish feeds on various small aquatic organisms - insect larvae, water donkeys, etc. When attacking, it envelops its prey in a web,penetrates 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.

Silver spider. Below is an unfinished bell-cocoon

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.

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.

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.

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 aquarium conditionsYoung spiders must be isolated from adults, since even the mother can eat them.

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 and description of appearance

The water spider is a small arthropod, with a body length of up to 15 mm. Males are larger than females, which is unusual for many species. The color is light or dark brown.

On a note!
It is called silverfish because of its ability to accumulate air bubbles around its abdomen.

The structure is typical - oval convex abdomen, cephalothorax, 4 pairs of limbs, chelicerae, pedipalps. A photo of the silver spider is presented below.

The entire body and legs are covered with long thick hairs. A special fatty lubricant produced by the arachnoid glands is concentrated on the surface. The secretion traps air bubbles around the body, allowing the spider to breathe underwater.

There are 8 in total. The main ones are located on the front of the cephalothorax - 2 large ones. They allow you to see images, shadows, silhouettes. The lateral ones are auxiliary, they react to movement, flickering light, and warn of the approach of prey or an enemy. The silverback water spider responds well to water fluctuations and vibration.

Lifestyle

The silverfish lives in stagnant bodies of water with green vegetation. Spends most of its life under water. Occasionally sticks its abdomen to the surface to take in air. The unique structure of the legs allows the arthropod to swim and dive well.

The water spider lives in a house that it makes out of air in the shape of a bell. How exactly he does this is difficult to describe. Initially, always, then attaches an air bubble to it and carefully climbs inside.

Interesting!
Females and males coexist peacefully in the neighborhood. The mating process necessarily takes place in the “lady’s” house. After the mating season, males retire to their home without fear for their own lives.

The lifespan of the water silverfish is no more than 18 months. In winter, they form a dense cocoon of cobwebs, climb inside or use empty shells. The entrance is covered with cobwebs, the house itself is attached to a plant, pot, and stones. The young generation and a small number of old females overwinter.

Nutrition

The silverback water spider is a typical predator. To catch prey, it builds trapping nets and stretches the threads to its house. During the waiting period, he sits inside, and at the first vibrations of the web he rushes to check the gear. The victims are aquatic insects, larvae, fry, and crustaceans.

Initially, the spider injects venom, paralyzing the prey, then saliva. Under the influence of special enzymes, the insides turn into a liquid mass, which is then sucked in by the predator. If the silverfish does not feel hungry, it drags the prey into its bell and hangs it there as a reserve.

Reproduction

The female is a caring, responsible mother. After fertilization, it forms a cocoon from the web and lays 50 to 100 eggs there. While it lasts incubation period, sitting in the house, not eating anything, waiting for the replenishment of the family. After about 2 weeks, the cubs appear. The mother lets them out to swim on their own. They build houses nearby or float away with the current over long distances.

Poisonous or not for humans

The silver water spider ranks third in toxicity of its poison after the karakurt and tarantula. However, it bites very rarely. A person can be accidentally injured by being pulled out of the water along with the fish. The bite is inflicted for the purpose of self-defense.

Redness, pain, burning, swelling, and swelling appear on the body. People prone to allergies, with weak immune systems, and young children may experience a deterioration in their health. Weakness, nausea, dizziness appear, headache, the temperature rises. The condition returns to normal in a few days. To speed up the therapeutic effect, take antihistamines.

The silverfish water spider is kept as pet in aquariums. In artificially created conditions, the arthropod lives for 18 months. They feed on insects.

Argyroneta aquatica (Cl.) Water Spider Status. 3 (VU) - vulnerable species. It is protected in a number of countries in Central Europe and some regions of Russia.

Short description. For the silver spider (another name dropsy vulgaris) is characterized by sexual dimorphism, unusual for spiders: the male (10-15 mm) is longer than the female (8-10 mm) due to a drop-shaped elongated olive-brown abdomen, covered with delicate light gray hairs. Underwater, these hairs trap a layer of air, causing the abdomen to turn silver. The cephalothorax is rusty-red with a slight brown pattern. almost naked.

Spreading. Transpalearctic. IN Leningrad region It is found everywhere and is associated with a wide variety of water bodies. Here it is quite rare, although in neighboring Finland it is not a species requiring special protection.

Ecology. The silverback is a true aquatic spider, building its bell-nests underwater in stagnant bodies of water or in streams and river backwaters with weak currents. The nests, the size of a small nut, are built from cobwebs, into which the spider brings air bubbles on its abdomen. It spends most of its life in nests. Adults are found from late May to June. For laying eggs, the female often builds a separate small bell, which she hangs next to the nest. The spider feeds on the larvae of aquatic insects and aquatic donkeys; it eats prey in the bell or on the surface of the water. All finds over the last hundred years are isolated; only in the northeast of the region can it be considered normal look(Oliger. 1996).

Limiting factors. All forms of pollution of water bodies and destruction of aquatic vegetation.

Security measures. Inclusion of the species in the lists of specially protected objects of the Nizhnesvirsky Nature Reserve. Identification of species habitats in existing and planned protected areas with subsequent development of protection measures.

Information sources. Oliger. 1996; Kharitonov. 1932: data from Y. Terhivuo.
V. A. Krivokhatsky, A. V. Gromov

Status. 3 (VU). Vulnerable. Protected in some Central European countries and Red Data Books of some regions of the Russian Federation.

Description. The Water Spider is characterized by sexual dimorphism, uncommon in spiders. The male (10-15 mm) is larger than the female (8 10 mm) because of a drop-like elongated olive-brown abdomen, covered with soft pale-gray short hairs. Under water these hairs bind air. and the abdomen becomes silvery. The cephalothorax is rusty-red w ith an undistinguished pattern, almost without hairs.

Distribution. Transpalaearctic species. In the Leningrad Region the species is distributed everywhere. It is rare in this region, though it is not a threatened species in neighboring Finland (J. Terhivuo, personal communication).

Ecology. An aquatic species. It builds a nest under water in stagnated lakes, slow springs or river backwaters. The nest, sized like a small nut. consists of a silk-like cobweb, which is filled with air. The spider brings air from the surface in bubbles on its abdomen. The spider spends most of its life in the nest. Adults can be found from the end of May to June. The female builds a separate small nest for the oviposilion. It feeds on water invertebrates, eating prey inside the nest or under the water surface. All present records of the species are single and sporadic, it is common only at the NE of the region (Oliger. 1996).

Limiting factors. The pollution of water reservoirs and the destruction of water plants.

Conservation measures. The species should be included in the list of specially protected objects in the Nizhnesvirsky strict nature reserve.

Sources of information. Oliger. 1996: Kharitonov. 1932: data from J. Terhivuo. I. I. Krivokhutsky, I. Gromov