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SPIDER WEB

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1. WHY IN THE NEWS?

Source: A still image from a social media video shows spiders’ gossamer near wetlands in Gippsland, Victoria, 2021, Australia. (Reuters)

  • Days after heavy rains and floods hit Australia’s Victoria in 2021, lakhs of spiders have spun webs that stretches across trees and paddocks creating huge gossamer-like sheets.
  • While the ballooning spiders are not dangerous to humans, some species are. Between 2000 and 2013, nearly 12,600 people were admitted to hospital because of spider bites.
  • Why have massive spider webs blanketed a region in Australia?
  • Days of intense rainfall have caused spiders to climb to higher ground using a survival tactic called “ballooning”, in which the insects throw out silk that latches on to vegetation, allowing them to escape.

[1] https://www.indiatoday.in/world/story/australia-s-victoria-covered-in-giant-spider-webs-after-flooding-see-photos-video-1816111-2021-06-17

(A still image from social media shows spiders’ gossamer near wetlands in Longford, Victoria, Australia June 14, 2021.(Reuters)

  • Observers have described the webbing as a single sheet crawling with small spiders, billowing like a wave.
  • In one area in Gippsland, a spider web covered more than a kilometer along a road, as per the BBC.
  • The webs are expected to fade away in one-two week.
  • Victoria state generally sees this natural phenomenon during the winter, when it receives most of its rain. When this happens, spiders, which can produce a wide variety of silks, produce this kind of web which is very thin and delicate, and allows them to fly away with the breeze, sometimes as far as 100 km.
  • Because this ballooning silk is lighter than air, it latches on to objects such as tree tops, tall grass and road signs, allowing the spiders to climb up. As per a report in the Guardian, the spiders which lay such webs are called “vagrant hunters”, which typically live on the ground and do not build a web. 
  • Even while ballooning after a flood, each spider throws up only one thread – meaning every line in the massive web blanket seen this week is made by a different insect; their total thus being expected in the millions.
Sydney Funnel Web Spider

(This eastern Australian native spider is one of the most feared of the venomous animals down under. They are typically 1 to 3 inches long, and can be very aggressive when provoked. The long-lived female Funnel Webs spend most of their time in their silk-lined tubular burrow retreats. The males tend to wander during the warmer months of the year looking for receptive females. The Sydney Funnel Web Spider is responsible for 13 confirmed deaths between1927-1980.)

2. SPIDER SYMBOLISM & MEANING (TOTEM, SPIRIT & OMENS)
  • The spider is the ultimate symbol of creativity. It shows its power in the way it spins its web. The spider is also aggressive and you can see its aggression in the way it traps, attacks, and kills its prey.
  • A spider’s web has two-fold meanings – it is a home for the spider, but it is also a trap for its victims. Since spider web is an engineering marvel, dreaming of spider webs may mean that creative ideas are being spun, but you must also wait patiently for the results.[1]
  • The spider’s spiral net or web converges into a single point in the center. Thus, the spider sitting in its web is the ultimate symbol of the center of the world or universe. 

[1] https://indianexpress.com/article/explained/explained-why-massive-spider-webs-have-blanketed-a-region-in-australia-7362048/

[1] Llewellyn’s Complete Dictionary of Dreams: Over 1,000 Dream Symbols and Their Universal Meanings (Llewellyn’s Complete Book Series, 5) Paperback – May 8, 2015

  • This is the reason why the spider is considered as the master of Illusion or Maya – the Hindu word for illusion. In India, the Rig-Veda describes the dawn as ‘being woven’ during the night because the full moon assists the spider. 
  • In some Native American myths, the spider is said to have taught humans the alphabet, tracing the shapes of the web. 
  • The spider gave the gift of the alphabet to the people so that they could record their journeys through the configurations offered in its web.
  • In some Native American cultures, the spider and its web bring the message of continual weaving of patterns, the infinite possibility of creation, and the importance of recording the complexities in our lives. Thus, the Natives viewed the spider as a wise entity that instructs, illuminates, and documents, rather than entrap and victimize.
  • China is known to have created the fishing net by imitating the spider’s web.
  • The spider spiritual meaning in Bible and Christian art is a miser who bleeds the poor people dry just as it itself bleeds its victims. Secondly, the spider represents the Devil for the Devil prepares its trap just as the spider prepares its web. Thirdly, it represents the malice of evil doers whose web will perish like those of the spider. Finally, the cobweb is a symbol of human frailty.[2]
  • Early Celts believed that spiders symbolized good luck. Small spiders were believed to be money spinners, so killing them was considered negative. No spider will spin its web on Irish oak. 
  • Spider meaning in dreams symbolizes fear. Freud believed that dreaming of spiders represents the mother that devours her children (which she does through possessiveness or guilt). 
  • When you dream of spiders, you are dreaming of webs, ancient knowledge, language, intricacy, and creativity, the circle of life, transmutation, feminine power, and creation. 
  • It could also be an indication that you are being cheated or that there is a web of deceit, lies, or fraudulent activity around you. Spider cobwebs also mean areas of your mind that you have locked away and that sit there covered with cobwebs.
  • Dreaming of being threatened by a spider suggests that you are anxious about being emotionally entangled in a particular situation in waking life.
  • In Japan, spiders appear in a number of myths and especially in the tale of Raiko. Most of these legends portray the spiders as evil beings that had to be vanquished by the heroes. However, the Japanese also revere the spider’s powers of spinning webs so intricately. So much so, that they have also honored the spider in the form of Yushkep Kamui – the Shinto spider Goddess. Many women pray to her for safe childbirth.
Image of The Yushkep Kamui (spider in Japan)

[4] Signs & Symbols in Christian Art: with Illustrations from Paintings of the Renaissance, Unabridged Edition Hardcover – January 1, 1959

[5] https://www.worldbirds.org/spider-symbolism/

Source: https://www.worldbirds.org/spider
Image of a spider web, taken from https://www.worldbirds.org/
3.GENERAL PHYSIOLOGY AND BEHAVIOUR OF SPIDER AND ITS WEB
  •  Spiders have two body regions: the cephalothorax and the abdomen.
  • All spiders have eight legs and six to eight eyes.
  • Female spiders, bored with male spiders and seeking to up their status, are known to kill and eat their male counterparts after having sexual intercourse with them.
  • Spiders can’t close their eyes because they don’t have eyelids, but they reduce their activity levels and lower their metabolic rate to conserve energy.[1] This is a useful ability, particularly for web-building spiders which depend on food coming to them and may have to go a long time between meals.
  • Many spiders are more active at night because a lot of creatures that would happily eat spiders, for instance birds, are more likely to be active by day. This helps them avoid becoming a snack.
  • Spider species such as the Australian Redback have been recorded going six months without food, yet were able to spring into action when presented with prey.
  • Male spiders are normally smaller and have different color markings than females.
  • No two spider webs are the same.
  • Spider venom includes different peptides and substances affecting sodium, calcium and potassium channels in neurons and also glutamate and acetylcholine receptors.
  • Three important syndromes are caused by spider bites: latrodectism, loxoscelism, and funnel-web spider syndrome.

 

4.IT’S CLASSIFICATION AND CHARACTERISTICS
  • Spiders belong to a branch of invertebrate animals called arthropods. Arthropods have the largest number of species. Along with ticks, mites and scorpions, spiders fall into the subphylum chelicerata and class of arachnids More than 40,000 different species of spiders are found in the world.
  • Spiders that make intricate webs to catch their prey are called “passive hunters.”
  • The spiders that don’t make elaborate webs are called “active hunters,” because they actively seek out their prey as they move around.
  • The most common species are;
  1. Cobweb spiders and 
  2. Cellar spiders
  • Both build webs where they lie in wait for prey to get caught. Cellar spiders sometimes leave their webs to hunt other spiders on their turf, mimicking prey to catch their cousins for dinner.
  • There’s even a species of jumping spider that prefers to eat blood-filled mosquitoesin African homes.

[6] https://www.tepapa.govt.nz/discover-collections/read-watch-play/science/your-bug-questions-answered/do-spiders-sleep

A cellar spider, sometimes called daddy longlegs (not to be confused with a harvestman). Matt Bertone, CC BY-ND

A Coweb Spider Image

3. WOLF SPIDERS

Wolf spiders are large and hairy with incredible eyesight. These creepy critters are agile hunters, but they do not build webs to catch their prey. They’re usually found on the ground or in burrows underground. Even though they are venomous, the bite symptoms humans experience are usually mild.

4.JUMPING SPIDERS

Jumping spiders are among the largest family of spiders, making up about 13 percent of all species. They are short, stout spiders that normally move relatively slow. However, they are known for being able to jump with extreme agility, especially while hunting. Some jumping spiders can jump 10 to 50 times the length of their bodies[7].
[7] https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=17989

5.GROUND SPIDERS

Ground spiders commonly make their homes under rocks, leaves, logs, and other objects on the ground. This group of spiders is normally red or gray-brown in color and can be solid or striped. They do not produce venom that can harm humans.

6.SAC SPIDERS

Sac spiders often reside in gardens, piles of leaves or wood, and timber. The population increases significantly during the fall, leading to many indoor infestations.

7.CRAB SPIDERS

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=17989

The front two pairs of a crab spider’s legs extend out to the side and are longer than the back two pairs. These legs are used primarily for hunting, since these spiders don’t make webs. Crab spiders are extremely patient hunters that are known to sometimes wait days or even weeks for their dinner.

8.VENOMOUS SPIDER

Black Widow, Brown Widow, Brown Recluse

Most spiders’ venom is not harmful to humans. But some spiders, like black and brown widows and the brown recluse, can inflict dangerous and painful bites. If any of these venomous spiders bite you or your family, seek immediate medical attention. If you find either of these venomous eight-legged critters in your home, especially in large numbers, your best bet is to contact a pest-control professional to help with removal.

 
5.GEOGRAPHICAL LOCATION OF FIVE OF THE WORLD’S DEADLIEST SPIDER
  1. The Brown Recluse Spideris one of the most dangerous spiders in the United States. Its venom destroys the walls of blood vessels near the site of the bite, sometimes causing a large skin ulcer.

2. Brazilian Wandering Spiders (Phoneutria feraand  nigriventer ) are sometimes also referred to as banana spiders because they are frequently found on banana leaves. They have an aggressive defense posture, in which they raise their front legs straight up into the air. Their venom is toxic to the nervous system, causing symptoms such as salivation, irregular heartbeat, and prolonged, painful erections (priapism) in men.

3. Yellow sac spider (Cheiracanthium inclusum) found throughout the United States, as well as in Mexico southward through South America, is venomous to humans and is often found indoors. The spider’s venom is a cytotoxin (a substance that destroys a cell or impairs its function) that can produce necrotizing lesions, but such lesions occur rarely in bite victims. Still, redness and swelling at the site of the bite are common reactions.

4. Wolf spider (family Lycosidae) a large and widespread group that is found throughout the world. They are named for their wolflike habit of chasing and pouncing upon prey. About 125 species occur in North America, whereas there are about 50 in Europe. They are noted for their running speed and commonly occur in grass or under stones, logs, or leaf litter, though they may invade human dwellings that harbor insects. Most species build silk-lined, tubular nests in the ground. Some conceal the entrance with rubbish, whereas others build a turret like structure above it. A few species spin webs. Wolf spider eggs are contained in a gray silk sac attached to the female’s spinnerets, or silk-producing organs, so that she appears to be dragging a large ball. After hatching, the young spiders ride on the mother’s back for several days. Although the spider is not considered to be aggressive, it will often bite people in self-defense. Wolf spiders are venomous, but their bites are not considered dangerous. The spider’s large fangs cause physical trauma at the site of the bite. 

5. Black Widow Spider (Latrodectus mactans) is responsible for more than 2,500 visits to poison control centers every year in the U.S. It is one species that can be found from the United States and parts of Canada through Latin America and the West Indies. The most common member of Latrodectusin North America, it makes its home in a variety of settings, such as woodpiles, burrows, or among plants that serve as supports for its web. The male, seldom seen because it is often killed and eaten by the female after mating (hence the spider’s name), is about one-fourth the size of the female. Its bite, which may feel like a pinprick on the skin, often produces severe muscle pain and cramping, nausea, and mild paralysis of the diaphragm, which makes breathing difficult. Most victims recover without serious complications. Although the bite is thought to be fatal to very small children and the elderly, no deaths have been attributed to bites by widow spiders in the United States.

6. HAVE YOU EVER WONDERED?
  • Why do spiders spin webs?
  • What are spiders webs made of?
  • How do spiders learn how to spin webs?
  • New research suggests that spider webs can lure their prey using, literally, electric attraction.[8]

  • [8] https://www.theatlantic.com/technology/archive/2013/07/confirmed-spiders-are-even-more-terrifying-than-previously-thought/277544/

(Spider web deformations produced by statically charged insects — bees, flies, aphids, fruit flies — and water drops (Victor Manuel Ortega-Jimenez and Robert Dudley)

  • The webs and positively charged objects did indeed seem to be attracted to each other. The silk threads in the web, for example, curved toward each other underneath a charged honeybee that was falling toward it – which would make it likelier that the bee would become entangled in the web.
  • Spiders produce silkthreads to build their webs.
  • The silk is produced in silkglands with the help of the spider’s spinnerets.
  • Spinnerets are special organs that allow the spider to decide what type of threadit needs for the web.[9]
  • The threads a spider uses to construct its web begin as liquid, but they dry quickly in the air.
  • Making webs is intrusive for spiders, which means nobody has to teach them how to do it. They are born knowing how.
  • When a spider begins a web, it releases a silk It anchors the thread to some object — a branch, a corner of a room, a doorframe — wherever it builds its web. As the spider moves back and forth, it adds more threads, strengthening the web and creating a pattern. Lines that go from the center of the web outward are called “radiallines.” They support the web. Threads that go around and around the web are called “orb lines.”
  • The main reason spiders spin webs is to catch their dinner. When an insect, such as a fly, flies into a spider’s web, it gets stuck on the sticky threads.
  • When a spider catches preyin the sticky strands of its web, it approaches the trapped insect and uses its fangs to inject venom. The venom either kills or paralyzes the prey, allowing the spider to enjoy its dinner in peace.

[9] https://www.wonderopolis.org/wonder/why-do-spiders-spin-webs

(In Georgia, this black widow spider (Latrodectus sp.) snared a juvenile scarlet snake (Cemophora coccinea) in its web. DANIEL R. CROOK.[10]

Take the Australian Redback. Not including legs, a female of this species of spider is only about the size of an M&M candy. But she can take down big prey — such as the eastern brown snake. It’s one of the most venomous serpents in the world. The spider’s web is a messy tangle of silk whose long, sticky threads dangle to the ground. A snake that mistakenly slides into this trap may get stuck. The Redback quickly throws more sticky silk to subdue her struggling victim. Then, chomp! Her bite delivers a powerful toxin that eventually kills the snake.)

[10] https://www.sciencenewsforstudents.org/article/spiders-catch-eat-surprisingly-big-snakes

  • Triangle Weaver spiders, use their webs like slingshots. When the Triangle Weaver makes its web, it pulls on each corner to create tension in the threads, just like you might pull back a slingshot and hold it.  When the Triangle Weaver senses its prey is near, it releases the web. The elastic potential energy is converted into kinetic energy and the system does the work of capturing a juicy meal for the spider.
  • Not all spiders use webs for food, however. Some don’t build webs at all. Other spiders chase their prey. Some even make sticky nets, which they throw over their prey when it gets close enough.
WHY ARE SO FEW SPIDERS HARMFUL TO HUMANS?
  • Much of the reason may result from the size differences between people and spiders. Spider venom is designed to work on smaller animals, but the venom of some species can produce skin lesions in people or produce allergic reactions that result in fatalities.[11]
  • Although they are generalist predators, apt to eat anything they can catch, spiders regularly capture nuisance pests and even disease-carrying insects – for example, mosquitoes. So killing a spider doesn’t just cost the arachnid its life, it may take an important predator out of your home.
  • They have lots of legs and almost all are venomous – though the majority of species have venom too weak to cause issues in humans, if their fangs can pierce our skin at all.
  • It is important to understand, however, that “death by spider bite” is very rare since clinics, poison control centers, and hospitals often have various species-specific antivenin (the antitoxin) on hand to treat the bite.
  • Spiders actually prefer to avoid humans; we are much more dangerous to them than vice versa. Bites from spiders are extremely rare. Although there are a few medically important species like widow spiders and recluses, even their bites are uncommon and rarely cause serious issues.[12]
  • If you truly can’t stand that spider in your house, apartment, garage, or wherever, instead of smashing it, try to capture it and release it It’ll find somewhere else to go, and both parties will be happier with the outcome.
  • Even if you don’t see them, they’ll still be there. So consider a live-and-let-live approach to the next spider you encounter.

[11] https://www.britannica.com/list/9-of-the-worlds-deadliest-spiders

[12] https://theconversation.com/institutions/north-carolina-state-university-1894

Photo: cobweb spider dispatches some prey that got snagged in its web. Matt Bertone, CC BY-ND

8. REFERENCES

Web links:

 

Journals:

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