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A spider web, spiderweb, spider's web, or cobweb (from the archaic word '' coppe'', meaning "spider") is a structure created by a spider out of proteinaceous spider silk extruded from its spinnerets, generally meant to catch its prey. Spider webs have existed for at least 100 million years, as witnessed in a rare find of
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
amber from
Sussex Sussex (), from the Old English (), is a historic county in South East England that was formerly an independent medieval Anglo-Saxon kingdom. It is bounded to the west by Hampshire, north by Surrey, northeast by Kent, south by the English ...
, in southern England. Many spiders build webs specifically to trap and catch insects to eat. However, not all spiders catch their prey in webs, and some do not build webs at all. "Spider web" is typically used to refer to a web that is apparently still in use (i.e. clean), whereas "cobweb" refers to abandoned (i.e. dusty) webs. However, the word "cobweb" is also used by biologists to describe the tangled three-dimensional web of some spiders of the family Theridiidae. While this large family is known as the cobweb spiders, they actually have a huge range of web architectures; other names for this spider family include tangle-web spiders and comb-footed spiders.


Silk production

When spiders moved from the water to the land in the Early
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
period, they started making silk to protect their bodies and their eggs. Spiders gradually started using silk for hunting purposes, first as guide lines and signal lines, then as ground or bush webs, and eventually as the aerial webs that are familiar today. Spiders produce silk from their spinneret glands located at the tip of their abdomen. Each gland produces a thread for a special purpose – for example a trailed safety line, sticky silk for trapping prey or fine silk for wrapping it. Spiders use different gland types to produce different silks, and some spiders are capable of producing up to eight different silks during their lifetime. Most spiders have three pairs of spinnerets, each having its own function – there are also spiders with just one pair and others with as many as four pairs. Webs allow a spider to catch prey without having to expend energy by running it down, making it an efficient method of gathering food. However these energy savings are somewhat offset by the fact that constructing the web is in itself energetically costly, due to the large amount of protein required in the form of silk. In addition, after a time the silk will lose its stickiness and thus become inefficient at capturing prey. It is common for spiders to eat their own web daily to recoup some of the energy used in spinning. Through ingestion and digestion, the silk proteins are thus recycled.


Types

There are a few types of spider webs found in the wild, and many spiders are classified by the webs they weave. Different types of spider webs include: * Spiral orb webs, associated primarily with the family
Araneidae Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...
, as well as
Tetragnathidae Long-jawed orb weavers or long jawed spiders (Tetragnathidae) are a family of araneomorph spiders first described by Anton Menge in 1866. They have elongated bodies, legs, and chelicerae, and build small orb webs with an open hub with few, wide-se ...
and Uloboridae * Tangle webs or cobwebs, associated with the family Theridiidae * Funnel webs, with associations divided into primitive and
modern Modern may refer to: History * Modern history ** Early Modern period ** Late Modern period *** 18th century *** 19th century *** 20th century ** Contemporary history * Moderns, a faction of Freemasonry that existed in the 18th century Phil ...
* Tubular webs, which run up the bases of trees or along the ground * Sheet webs Several different types of silk may be used in web construction, including a " sticky" capture silk and "fluffy" capture silk, depending on the type of spider. Webs may be in a vertical plane (most orb webs), a horizontal plane (sheet webs), or at any angle in between. It is hypothesized that these types of aerial webs co-evolved with the evolution of winged insects. As insects are spiders' main prey, it is likely that they would impose strong selectional forces on the foraging behavior of spiders. Most commonly found in the sheet-web spider families, some webs will have loose, irregular tangles of silk above them. These tangled obstacle courses serve to disorient and knock down flying insects, making them more vulnerable to being trapped on the web below. They may also help to protect the spider from predators such as birds and wasps. It is reported that several ''
Nephila pilipes ''Nephila pilipes'' (northern golden orb weaver or giant golden orb weaver''Nephila pilipes''
Ar ...
'' individuals can collectively construct an aggregated web system to counter bird predation from all directions.


Orb web construction

Most orb weavers construct webs in a vertical plane, although there are exceptions, such as ''
Uloborus diversus ''Uloborus diversus'' is a species of cribellate orb weaver in the spider family Uloboridae Uloboridae is a family of non-venomous spiders, known as cribellate orb weavers or hackled orb weavers. Their lack of venom glands is a secondarily evol ...
'', which builds a horizontal web. During the process of making an orb web, the spider will use its own body for measurements. There is variation in web construction among orb-weaving spiders, in particular, the species ''
Zygiella x-notata ''Zygiella x-notata'', sometimes known as the missing sector orb weaver or the silver-sided sector spider,Factsheet 6: Missing-sector Orbweaver (Zygiella x-notata)', British Arachnological Society, 2016. Retrieved 27 November 2016 is a spider sp ...
'' is known for its characteristic missing sector web crossed by a single signal thread. Many webs span gaps between objects which the spider could not cross by crawling. This is done by first producing a fine adhesive thread to drift on a faint breeze across a gap. When it sticks to a surface at the far end, the spider feels the change in the vibration. The spider reels in and tightens the first strand, then carefully walks along it and strengthens it with a second thread. This process is repeated until the thread is strong enough to support the rest of the web. After strengthening the first thread, the spider continues to make a Y-shaped netting. The first three radials of the web are now constructed. More radials are added, making sure that the distance between each radial and the next is small enough to cross. This means that the number of radials in a web directly depends on the size of the spider plus the size of the web. It is common for a web to be about 20 times the size of the spider building it. After the radials are complete, the spider fortifies the center of the web with about five circular threads. It makes a spiral of non-sticky, widely spaced threads to enable it to move easily around its own web during construction, working from the inside outward. Then, beginning from the outside and moving inward, the spider methodically replaces this spiral with a more closely spaced one made of adhesive threads. It uses the initial radiating lines as well as the non-sticky spirals as guide lines. The spaces between each spiral and the next are directly proportional to the distance from the tip of its back legs to its spinners. This is one way the spider uses its own body as a measuring/spacing device. While the sticky spirals are formed, the non-adhesive spirals are removed as there is no need for them any more. After the spider has completed its web, it chews off the initial three center spiral threads then sits and waits, usually with the head facing downwards. If the web is broken without any structural damage during the construction, the spider does not make any initial attempts to rectify the problem. The spider, after spinning its web, then waits on or near the web for a prey animal to become trapped. The spider senses the impact and struggle of a prey animal by vibrations transmitted through the web. A spider positioned in the middle of the web makes for a highly visible prey for birds and other predators, even without web decorations; many day-hunting orb-web spinners reduce this risk by hiding at the edge of the web with one foot on a signal line from the hub or by appearing to be inedible or unappetizing. Spiders do not usually adhere to their own webs, because they are able to spin both sticky and non-sticky types of silk, and are careful to travel across only non-sticky portions of the web. However, they are not immune to their own glue. Some of the strands of the web are sticky, and others are not. For example, if a spider has chosen to wait along the outer edges of its web, it may spin a non-sticky prey or signal line to the web hub to monitor web movement. However, in the course of spinning sticky strands, spiders have to touch these sticky strands. They do this without sticking by using careful movements, dense hairs and nonstick coatings on their feet to prevent adhesion. File:Typical-orb-web-photo.jpg, A typical orb web constructed by an ''
Araneus ''Araneus'' is a genus of common orb-weaving spiders. It includes about 650 species, among which are the European garden spider and the barn spider. The genus was erected by Carl Alexander Clerck in 1757. Description Spiders of this genus prese ...
'' (family
Araneidae Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...
) spider File:Garden orb weaver05.jpg,
Australian garden orb weaver spider The Australian garden orb weaver spider (''Hortophora transmarina'') is a very common species of spider with many variants in size, shape, and colour across the coastal and northern regions of Australia. They have very large abdomens when well-f ...
, after having captured prey


Uses

Some spiders use their webs for hearing, where the giant webs function as extended and reconfigurable auditory sensors. Some species of spider do not use webs for capturing prey directly, instead pouncing from concealment (e.g. trapdoor spiders) or running them down in open chase (e.g. wolf spiders). The
net-casting spider Deinopidae, also known as net casting spiders, is a family of cribellate spiders first described by Carl Ludwig Koch in 1850. It consists of stick-like elongated spiders that catch prey by stretching a web across their front legs before propelling ...
balances the two methods of running and web spinning in its feeding habits. This spider weaves a small net which it attaches to its front legs. It then lurks in wait for potential prey and, when such prey arrives, lunges forward to wrap its victim in the net, bite and paralyze it. Hence, this spider expends less energy catching prey than a primitive hunter such as the wolf spider. It also avoids the energy loss of weaving a large orb web. Some spiders spin threads of silk to catch the wind and then sail on the wind to a new location. Some spiders manage to use the signaling-snare technique of a web without spinning a web at all. Several types of water-dwelling spiders rest their feet on the water's surface in much the same manner as an orb-web user. When an insect falls onto the water and is ensnared by
surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...
, the spider can detect the vibrations and run out to capture the prey.


Human use

Cobweb painting Cobweb painting, sometimes known as gossamer painting, is the delicate process of painting on canvases made from caterpillar and spider webs that have been collected, layered, cleaned, and framed. Fewer than 100 cobweb paintings are known to exist ...
s, which began during the 16th century in a remote valley of the Austrian Tyrolean Alps, were created on fabrics consisting of layered and wound cobwebs, stretched over cardboard to make a mat, and strengthened by brushing with milk diluted in water. A small brush was then used to apply watercolor to the cobwebs, or custom tools to create engravings. Fewer than a hundred cobweb paintings survive today, most of which are held in private collections. In traditional European medicine, cobwebs were used on wounds and cuts to reduce bleeding and aid healing. This use was recorded in ancient Greece and Rome, and was mentioned in Shakespeare's ''
A Midsummer Night's Dream ''A Midsummer Night's Dream'' is a comedy written by William Shakespeare 1595 or 1596. The play is set in Athens, and consists of several subplots that revolve around the marriage of Theseus and Hippolyta. One subplot involves a conflict amon ...
''. Spider webs have been shown to significantly reduce wound healing times. They are rich in vitamin K, which is essential in blood clotting, and their large surface area is also thought to help coagulation. The effects of some drugs can be measured by examining their effects on a spider's web-building. In northeastern Nigeria, cow horn resonators in traditional xylophones often have holes covered with spider webs to create a buzzing sound. Spider web strands have been used for crosshairs or reticles in telescopes. Development of technologies to mass-produce spider silk has led to the manufacturing of
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
military protection, wound dressings and other medical devices, and consumer goods. Spider webs can be used as a single step catalyst to make nanoparticles.


Physical and chemical properties

The stickiness of spiders' webs is due to droplets of glue suspended on the silk threads. These glue balls are multifunctional – that is, their behavior depends on how quickly something touching a glue ball attempts to withdraw. At high velocities, they function as an elastic solid, resembling rubber; at lower velocities, they simply act as a sticky glue. This allows them to retain a grip on attached food particles. The web is electrically conductive which causes the silk threads to spring out to trap their quarry, as flying insects tend to gain a static charge which attracts the silk.
Neurotoxin Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...
s have been detected in the glue balls of some spider webs. Presumably these toxins help immobilize prey, but their function could also be antimicrobial, or protection from ants or other animals that steal from the webs or might attack the spider. Spider silk has greater tensile strength than the same weight of
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
and much greater
elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the cl ...
. Its microstructure is under investigation for potential applications in industry, including
bullet-proof vests A bulletproof vest, also known as a ballistic vest or a bullet-resistant vest, is an item of body armor that helps absorb the impact and reduce or stop penetration to the torso from firearm-fired projectiles and Fragmentation (weaponry), fragment ...
and artificial
tendons A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
. Researchers have used genetically modified mammals and bacteria to produce the
proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
needed to make this material.


Communal spider webs

Occasionally, a group of spiders may build webs together in the same area. Massive flooding in Pakistan during the 2010 monsoon drove spiders above the waterline, into trees. The result was trees covered with spider webs. One such web, reported in 2007 at
Lake Tawakoni State Park Lake Tawakoni State Park ( ) is a state park located in Hunt County, Texas, United States, north of Wills Point. It is on the south central shore of Lake Tawakoni. History Constructed in 1960, the lake is named after the Tawakoni Native Americ ...
in Texas, measured across.
Entomologist Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arach ...
s believe it may be the result of social cobweb spiders or of spiders building webs to spread out from one another. There is no consensus on how common this occurrence is. In Brazil, there have been two instances of a phenomenon that became known as "raining spiders"; communal webs made by "social" spiders that cover such wide gaps and which strings are so difficult to see that hundreds of spiders seem to be floating in the air. The first occurred in
Santo Antônio da Platina Santo Antônio da Platina is a municipality in the state of Paraná in the Southern Region of Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and L ...
, Paraná, in 2013, and involved '' Anelosimus eximius'' individuals; the second was registered in
Espírito Santo do Dourado Espírito Santo do Dourado is a municipality in the state of Minas Gerais in the Southeast region of Brazil. See also *List of municipalities in Minas Gerais This is a list of the municipalities in the state of Minas Gerais (MG), located in the ...
, Minas Gerais, in January 2019, and involved ''
Parawixia bistriata ''Parawixia bistriata'' is a spider species found mainly in South America. It is known to have social foraging behavior. Due to its complex social system, it can live in habitats with various resource levels. Recently, its social behavior has bee ...
'' individuals.


Low gravity

It has been observed that being in
Earth's orbit Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi) in a counterclockwise direction as viewed from above the Northern Hemisphere. One complete orbit takes  days (1 sidereal year), during which time Earth ...
has an effect on the structure of spider webs in space. Spider webs were spun in low Earth orbit in 1973 aboard Skylab, involving two female
European garden spider The spider species ''Araneus diadematus'' is commonly called the European garden spider, diadem spider, orangie, cross spider, and crowned orb weaver. It is sometimes called the pumpkin spider, although this name is also used for a different spec ...
s (cross spiders) called Arabella and Anita, as part of an experiment on the Skylab 3 mission. The aim of the experiment was to test whether the two spiders would spin webs in space, and, if so, whether these webs would be the same as those that spiders produced on Earth. The experiment was a student project of Judy Miles of Lexington, Massachusetts. After the launch on July 28, 1973, and entering Skylab, the spiders were released by
astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
Owen Garriott Owen Kay Garriott (November 22, 1930 – April 15, 2019) was an American electrical engineer and NASA astronaut, who spent 60 days aboard the Skylab space station in 1973 during the Skylab 3 mission, and 10 days aboard Spacelab-1 on a Spac ...
into a box that resembled a window frame. The spiders proceeded to construct their web while a camera took photographs and examined the spiders' behavior in a
zero-gravity Weightlessness is the complete or near-complete absence of the sensation of weight. It is also termed zero gravity, zero G-force, or zero-G. Weight is a measurement of the force on an object at rest in a relatively strong gravitational fi ...
environment. Both spiders took a long time to adapt to their weightless existence. However, after a day, Arabella spun the first web in the experimental cage, although it was initially incomplete. The web was completed the following day. The crew members were prompted to expand the initial protocol. They fed and watered the spiders, giving them a house fly. The first web was removed on August 13 to allow the spider to construct a second web. At first, the spider failed to construct a new web. When given more water, it built a second web. This time, it was more elaborate than the first. Both spiders died during the mission, possibly from dehydration. When scientists were given the opportunity to study the webs, they discovered that the space webs were finer than normal Earth webs, and although the patterns of the web were not totally dissimilar, variations were spotted, and there was a definite difference in the characteristics of the web. Additionally, while the webs were finer overall, the space web had variations in thickness in places: some places were slightly thinner, and others slightly thicker. This was unusual, because Earth webs have been observed to have uniform thickness. Later experiments indicated that having access to a light source could orient the spiders and enable them to build their normal asymmetric webs when gravity was not a factor.


In popular culture

Spider webs play a crucial role in the 1952 children's novel ''
Charlotte's Web ''Charlotte's Web'' is a book of children's literature by American author E. B. White and illustrated by Garth Williams; it was published on October 15, 1952, by Harper & Brothers. The novel tells the story of a livestock pig named Wilbur and his ...
''. Webs are also featured in many other
cultural depictions of spiders Throughout history, spiders have been depicted in popular culture, mythology and in symbolism. From Greek mythology to African folklore, the spider has been used to represent a variety of things, and endures into the present day with characters su ...
. In films, illustration, and other visual arts, spider webs may be used to readily suggest a "spooky" atmosphere, or imply neglect or the passage of time. Artificial "spider webs" are a common element of
Halloween Halloween or Hallowe'en (less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve) is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Saints' Day. It begins the observanc ...
decorations. Spider webs are a common image in tattoo art, often symbolizing long periods of time spent in prison, or used simply to fill gaps between other images. Some observers believe that a small spider is depicted on the United States one-dollar bill, in the upper-right corner of the front side ( obverse), perched on the shield surrounding the number "1". This perception is enhanced by the resemblance of the background image of intertwining fine lines to a stylized spider web. However, other observers believe the figure is an owl. The World Wide Web is thus named because of its tangled and interlaced structure, said to resemble that of a spider web. Artificial spider webs are used by the superhero
Spider-Man Spider-Man is a superhero appearing in American comic books published by Marvel Comics. Created by writer-editor Stan Lee and artist Steve Ditko, he first appeared in the anthology comic book '' Amazing Fantasy'' #15 (August 1962) in the ...
to restrain enemies and to make ropes on which to swing between buildings as quick transportation. Some incarnations of the character, such as the version in the Sam Raimi film trilogy and Spider-Man 2099, are shown to be able to produce organic webs. The notable tensile strength of spider webs is often exaggerated in science fiction, often as a plot device to justify the presence of artificially giant spiders. Posters were used by the women at Greenham Common Women's Peace Camp, and often featured the symbol of a spider web, meant to symbolise the fragility and perseverance of the Greenham women.


See also

*
Filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
* Effect of psychoactive drugs on animals#Spiders


References


External links


Beautiful Spider Web Build Time-lapse
by BBC Earth {{Authority control Arachnology
Web Web most often refers to: * Spider web, a silken structure created by the animal * World Wide Web or the Web, an Internet-based hypertext system Web, WEB, or the Web may also refer to: Computing * WEB, a literate programming system created by ...
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