How does a silver spider breathe underwater? Silver spider and all the most interesting about it Water spider species
Is it possible to live at the bottom of a reservoir and breathe at the same time atmospheric air? A lot of people think this is a stupid question. Yes, it is understandable. Where can atmospheric air come from at the bottom of the reservoir? Concerning aquatic life, then they either breathe oxygen dissolved in water, using gills for this, or periodically rise to the surface to take atmospheric air into their lungs.
And yet, this question is not as stupid as it seems at first glance. A silver spider can breathe atmospheric air, and at the same time constantly be at the bottom of a reservoir. Scientists even joke about this, saying that this insect managed to build a real castle in the air under water. And yet, they are not far from the truth. The spider sinks to the bottom of the reservoir along with an air bubble that is attached to its abdomen. In addition, he himself is inside the air bell, which communicates with the air bubble.
You can meet this original insect in Europe, Kazakhstan, Asia and the Caucasus. It is unremarkable, and appearance completely different from their land relatives. The body of the spider has a brown color, with many black spots. The cephalothorax is devoid of hair. Silver has eight eyes. Females are smaller than males. Scholars agree that due to larger size the male does not fall prey to the female after mating.
You can meet this spider in reservoirs with stagnant water and rough aquatic vegetation. As you may have guessed, he breathes with the help of his lungs. The body of an insect is covered with small hairs, which are lubricated with a water-repellent liquid produced by its glands. It is on these hairs that air bubbles linger, which supply the spider with air. It is quite enough for a long stay under water.
The female and male have different air bubbles. In the male, the air reservoir is attached to the underside of the abdomen. In the female, it occupies its entire surface. That is why she can only swim upside down. The male, in this respect, is much more agile. It can float both horizontally and vertically. To take a horizontal position, he carefully works with his paws.
The air bell, in which the silverfish lives, is the size of a pigeon's egg. The spider fastens it with a web to aquatic plants and various subjects located at the bottom of the reservoir. Periodically, the spider replenishes the bell with air, which it delivers from the surface, in the form of air bubbles attached to the body. Having reached the goal, the spider separates the bubble from the body with its paws, and attaches it to the dome. To attach an air bubble to the body, the spider rises to the surface, sticks out part of the abdomen from the water, grabs the bubble with spider warts, and quickly dives under the water. The air supply is enough for about a day.
In addition to air bubbles delivered by the spider from the surface, the bell is replenished with oxygen through gas exchange. In other words, it is extracted from the water, with the simultaneous removal of carbon dioxide. At the same time, the need for its replenishment with air bubbles remains.
The spider's diet consists of small crustaceans and invertebrates, which it catches in its webs. The sight of a silverfish is unimportant, therefore, he is forced to navigate in space with the help of his legs, which are equipped with sensitive receptors and can perceive even the slightest fluctuations in water. Upon receiving such a signal, the spider jumps out of its shelter and pounces on the victim stuck in its web. He injects digestive fluid into her and waits for it to be digested. As soon as the process is completed, the spider drags food into its home and regales itself while lying on its back. In this position, the nutrient broth does not leak, but goes directly into the stomach of the insect. The spider removes the remains of organic matter outside the bell.
To breed offspring, the female silverfish braids the top of the dome with a soft web, on which, subsequently, she lays up to 150 eggs. She vigilantly guards the masonry, hanging upside down on the web. At this time, she practically stops eating, and only replenishes the dome with air. After ten days, spiderlings hatch from the eggs. They are completely bald and cannot exist on their own outside the dome. They will be ready for independent life only after the second molt.
With the onset of cold weather, the silver spider builds winter shelter using an empty clam shell for this. He attaches it to the algae floating on the surface of the reservoir, fills it to capacity with air bubbles, climbs inside, and tightly seals the inlet. To minimize air consumption, the spider goes into a torpor. In winter, algae sink to the bottom of the reservoir, dragging the shell with them. The spider will wake up with the onset of spring heat. Sun rays warm the water, the algae will float to the surface along with the shell, and the spider will be able to leave its winter shelter.
Good evening, dear readers site Sprint-Answer. Today is October 14, 2017 on our calendars, which means that it's time for another Saturday episode of the TV game "Who want to be a millionaire?" for 10/14/2017. FROM complete overview Today's game can be viewed by clicking on the link above. And in this article we will dwell on the seventh question for Alexander Revva and Vera Brezhneva.
What does a silver spider fill its underwater nest with?
The silver spider, or water spider (lat. Argyroneta aquatica) is a species of spiders common in Europe from the Cybaeidae family. Differs in long swimming setae on the hind legs and 3 claws on the legs of the 3 hind pairs.
The correct answer is traditionally highlighted in blue and bold, but for now there is still some information about the silver spider from Wikipedia.
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 (since it is not displaced due to the surface tension of water), and therefore it appears silver under water. This layer of air allows the silverfish to stay under water for a long time; it occasionally rises to its surface to renew its supply of air. The water-repellent substance is a modified secretion of the spider glands.
7. What does a silver spider fill its underwater nest with?
- fly wings
- algae
- air bubbles
- pearls
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 is not so easy to find a spider in an ordinary body of water, but when you see it, you will know right away. The attention of the observer is attracted by a magnificent air bell, in which the spider sits. Its abdomen is entirely placed inside the bell, part of the cephalothorax and legs are exposed outside - the silverfish lies in wait for prey. So he grabbed the water donkey, dragged him into the air bell and began to eat. Having finished with the crustacean, the spider got out of the bell, threw out the remains of the prey and floated to the surface of the water. I wonder how the spider breathes under water 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 in the air under water. On the ventral side, it is covered with dense hairs: there are about 1,250 hairs per square millimeter of its body surface. All hairs are tilted backwards, some of them are longer, thicker, set less frequently, while others are shorter, denser, strongly pubescent. A layer of air is held between the dense lower hairs, fitting the spider's abdomen. The role of the 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 bladder and move it away from the body, thus increasing the cavity of the bladder. 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 bladder in males and females is different. So that the hairs do not stick together and perform their supporting role well, the silverfish combs and lubricates them, rubbing the body with the paws of the 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 secret, which soon emerges from the mouth. The spider wets the paw in it, first of one leg, then the other, and wipes 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 out its abdomen as high as possible above the water so that it is completely exposed to air. Having ventilated the lungs and the hairline of the abdomen, the silverfish slowly descends into the water, working like oars with four pairs of legs and carrying away the supply of air on the hairs. During the replenishment of air supplies, the spider is completely defenseless, therefore, in the process of evolution, it has improved ways to stay under water for 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 secret, breathing with the help of not only the lungs, but also the entire surface - all these are adaptations for the economical use 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 net, very similar to the web of terrestrial spiders. As it fills with air, the bell acquires 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 along an existing cobweb or aquatic plants, laying a web after itself. When the spider touches the surface of the water, it abruptly changes position, turning 180 degrees with the end of the abdomen up. This moment is very important, because with the help of arachnoid warts, the surface tension films of the air bubble surrounding the body of the spider 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 set the hairs of the torn, 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 bends so that it lies obliquely on the dorsal side of the abdomen, and the other 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 whole body of the spider down, its hind legs instantly straighten, their paws cross, and the surface layer of water lying on bent legs, is pulled up along with them. There is, as it were, a cutoff of a certain amount of air 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 was built, clinging to the web. The first vial is carefully woven into the fabric of the bell's cobweb roof. The spider touches different parts of the roof with arachnoid warts, attaching the threads with which the air bubble entangles, similar to how they fix Balloon. The second and third bubbles are let in under the bell by touching the first one. After the third time, the bell is already large enough to drag a water donkey into it and eat it. But the building is not finished yet.
Silver works, bringing more and more portions of air, braiding the bell with new layers of cobwebs, first from the inside, then from the outside. The spider conducts new reinforcing threads to surrounding objects, weaves masking plants into the walls.
How does a silver spider eat?
As already mentioned, silverfish lie in wait for prey, sitting in a bell. The hairs on the paws and pedipalps of the spider play the role of organs of touch, with which he feels 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 tremors. As soon as a small crustacean touches one of the threads of the web, directed in different directions from its bell, the spider immediately feels this and immediately rushes at the victim. Returning to the bell with a crustacean in 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 it, but remains in the recess of the mouth. Digestion in silverfish, like in all spiders, is extraintestinal. Enzymes secreted outside digest the soft tissues of the victim, which are then absorbed by the spider. Undigested remains are carried out by the spider.
Silverfish males are somewhat larger than females, which is quite rare in spiders, so mating usually occurs quite peacefully. Before breeding, the male builds a special small bell closed on all sides, lies down 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 side of the bell to the other. At the same time, separate threads emerge from the holes of the spider webs, which do not stick to each other. The spider then secretes the sperm onto these threads and collects them from there with the tentacles of the pedipalps. After that, he rests again and after a while goes in search of a female.
Reproduction of silver spiders
Mating takes place in the female's summer bell.
The fertilized female proceeds to lay eggs, for which she rearranges her summer bell into an egg bell. The female lines the top of the bell with a loose web and lays from 15 to 160 eggs on it. She seals the eggs with cobwebs, and now the bell consists of two chambers - egg and residential. The female sits on the eggs head down and guards them until the hatched spiders leave the nest. At this time, she does not take food and only occasionally leaves the bell to renew her air supply. In summer, the development of eggs lasts about 10 days. Young spiderlings emerge from their eggs hairless, and therefore can only breathe while inside the mother's bell. The first two molts of young silverfish also pass here, after which the spiderlings leave their mother's bell and move on to an independent life. The mother immediately stops recognizing them and, on occasion, can eat them. Spiders grow quickly and good nutrition after three months they reach the 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 molting. The molting process begins with the rupture of the old integuments on the cephalothorax, then on the abdomen. After that, 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 rises, feels his old skin and sits on it, while trembling slightly. 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 hibernate in different stages: adult males on wintering are less common than females; most of all among wintering young spiders. Sometimes late egg cocoons winter together with 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 vitreous mass. Sometimes spiders hibernate in empty shells of mollusks. There they also weave a cobweb cocoon, but less dense. Spider shells often freeze into ice, but silverfish tolerate such a harsh winter very well. In spring, the shells and wintering bells of spiders are carried by floods, which serves as an adaptation for their settlement.
Our common dolomedes spider is associated with water, 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 most Dolomedes pick up 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 on the surface of the water. The spider responds to single strikes on water only in 15% of cases, but with prolonged strikes, it determines not only the direction, but even the distance to the source of the wave. Spiders, as it were, feel the waves with their legs, measuring their amplitude and determining the distance to the victim from it. Dolomedes builds a cocoon for laying eggs on near-water plants.
Description
The male, which is larger than the female (this prevents female cannibalism), reaches 15 mm in length, the female up to 12; almost naked cephalothorax of brownish color, turning into blackish, with black lines and spots; the abdomen is brown, covered with many velvety hairs and presents 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 (since it is not displaced due to the 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; it occasionally rises to its surface to renew its supply of air. The water spider is caught in stagnant or slowly flowing waters quite often.
The water spider feeds on various small animals that get entangled in the threads of its underwater web, or which it catches while swimming in the water. Caught excess prey, he sometimes hangs in his nest.
Nest
A silverfish makes a bell-shaped or funnel-shaped nest under water from cobwebs, attaching it to various underwater objects. The nest, open at the bottom and reaching the size of a hazelnut, the spider fills 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 the abdomen, while pushing 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 vesicle 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
Eggs are laid in a cocoon of cobwebs containing air and placed near 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.
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The only underwater spider in the world July 4th, 2015
Family representative Argyronetidae - Argyroneta aquatica the only spider that has adapted perfectly to an underwater existence. It is most often found in stagnant or slowly flowing waters rich in vegetation.
Silverfish spiders adapt well to aquarium conditions. They can be kept in any vessels - both in glass jars (one copy each) and in large containers (several adults). At the same time, the presence of aquatic plants is mandatory, among which spiders build their dwelling.
Let's look at it in more detail...
Photo 2. 
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 mandibles: 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 happens 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 secret secreted by chelicerae. Under water, part of the air is retained by hairs, forming a silvery airy film (hence the name of the water spider).
Photo 3. 
The silverfish feeds on various small aquatic organisms- insect larvae, water donkeys, etc. Attacking, she wraps her prey in cobwebs, digs into it with chelicerae and poisons with secretions of poisonous glands. Then it injects a digestive secret and, after liquefying the tissues, sucks the contents out of its prey.
Photo 4. 
In captivity, these spiders can be fed on 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 spider 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 hardens quickly, turning into strong transparent threads. The web filled with air forms a bell.
Photo 5. 
It happens in the following way. The spider weaves a web of cobweb threads under water, attaching it to aquatic plants and other objects. Then he begins to drag air inward, bringing it from the surface of the water. To do this, the spider crawls along the stems of plants and pulls the thread along which it returns, as the air bubble pushes it up.
It takes about three hours to build a small bell. During this time, the spider rises to the surface up to 80 times. Air is held under water by a spider web. The resulting dome reaches the size of a pigeon's egg. There can be several bells in an aquarium different shapes. In them, spiders eat caught prey, care for hairs, etc.
In nature, for the winter, spiders arrange a bell-cocoon under water, in which they hibernate. In an aquarium with enough food, they always lead an active lifestyle.
Photo 6. 
Usually in silverfish, males and females are almost the same size, but there is a variety in which males are much larger. You can determine the sex by the light gray color of the back of the body in females and the more elongated abdomen in males. Unlike other spiders, silverfish have a peaceful relationship between the sexes.
When breeding, water spiders lay their 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 fixed with gossamer threads. The female guards the clutch and takes care of it.
Photo 7. 
Spiderlings hatched after 10 days do not immediately leave their mother. They molt, grow up, and only then, leaving the cocoon, scatter to start building their underwater homes.
Juveniles are yellowish-gray or yellow-brown. With age, the spiders darken and a black tint begins to predominate in the 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 over land, when keeping them in captivity, it is necessary to tightly close the aquarium (jar) with a cover glass, leaving air space above the surface of the water.
Photo 9. 
In order to breathe, water spiders build web nests that visually resemble domes - in these nests they store 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 paws.
Scientists have long established these abilities of spiders to transport air bubbles under water, but no one has paid attention to the ability of the spider's air capsule to absorb oxygen in the water. Whether such a feature is inherent in underwater spider nests that store oxygen, two Australian scientists Stefan Hetz and Roger Seymour tried to find out. To understand how water can satisfy the need of spiders for oxygen, scientists started experiments. At the same time, it was assumed that it is from the water that the spiders capture oxygen, the concentration of which in the domes decreases from time to time.