Pages

Wednesday 27 May 2015

10 MYTHS ABOUT SPIDERS


wpsD587.tmp
10 Myths About Spiders
By Chris Opfer,
How Stuff Works, 22 May 2015.

Spiders are just like you and me. That is, they're largely misunderstood. Maybe it's their eight gangly legs and hairy bodies. Or maybe it's those little fangs that inject venom into their prey. Whatever it is, the sight of a spider tends to give folks the willies. Sure, Peter Parker has repeatedly saved the world on the big screen by channelling his inner arachnid, donning a red and blue spider suit and shooting webs at bad guys, but that doesn't seem to have done much for spider awareness.


The fact is that many of us have our "facts" wrong when it comes to spiders. We assume these creepy crawlers spend their time looking for ways to frighten the daylights, bejesus and living poop out of people. Turns out, they're probably as put off by humans as we are by them. They're not likely to bite a person or crawl into your sleeping mouth and they may even prefer spending their days indoors. Some of them don't even spin webs. Let's look at 10 spider myths that don't hold up to scrutiny, starting with the biggest one of all.

10. Spiders Are Not Insects

wps2D19.tmp
Photo: Troup Dresser/Flickr

This is one of those common misconceptions that sounds like it's actually true. Spiders are tiny and often dark creatures that crawl around on their little legs. Like wasps, crickets and caterpillars, spiders don't have spines. They also seem to share an innate ability to get inside homes, cars and other places where they aren't "supposed" to be.

There are a few physical aspects that set spiders and other members of the Arachnida group - like mites and ticks - apart from their insect friends. The Insecta group is characterized by three main body parts: the head, thorax and abdomen. Spiders, on the other hand, have only two main body parts: the cephalothorax - a combined head and thorax covered by a hard shell - and the abdomen. They lack an insect-like antennae and have one more set of legs than insects, which generally feature six limbs [source: Explorit Science Centre].

Spiders also probably look better in a bathing suit. Their slender waists distinguish spiders from other arachnids [source: Explorit Science Centre].

9. All Spiders Make Webs

wps1AF0.tmp
Photo: Steve Calcott/Flickr

For many folks, the first thing that comes to mind when talking about spiders is the idea that these creatures were born to spin webs. The truth is, not all spiders spend their days creating them.

The intricate and surprisingly sturdy nets that many spiders produce is an important part of how some of these creatures put food on the table. They use the webs to trap insects and other prey to feast on later. Other types of spiders, however, hunt the old-fashioned way. Wolfspiders, for example, burrow into the ground. They use rocks and spin silk funnels to fortify their bunkers in the winter months and they stalk prey openly for food [sources: Ogg, Explorit Science Centre].

Tarantulas also hunt on foot, and shoot silk streams, Spider Man-style, to keep a grip on slippery surfaces. Runningcrabspiders, named for their crustacean appearance, get their food by playing dead. They lie in wait motionless and ambush insects as they pass by [sources: Kaufman, Masta].

8. The Orb Web Is Typical

wps8B99.tmp
Large orb web of European garden spider. Photo: Gnissah/Wikimedia Commons.

If you grew up on "Charlotte's Web," E.B. White's popular children's novel about the friendship between a barn spider and a talking pig, then you may be forgiven for assuming that all spiders spin large, ornamental webs with witty messages written into them. As we've already learned, however, many spiders don't spin webs at all. Those that do, spew their silk in a wide variety of ways.

Spiders produce silk from glands located beneath the abdomen. The silk itself is a protein that initially comes out in liquid form and hardens as it leaves the glands. Some of it is used to make webs, while the rest goes toward wrapping up prey and creating sacs for eggs [source: Explorit Science Centre].

Orb webs - the circular type nets formed from a series of spirals - are probably the best-known, but they're far from the only type of silk creations that spiders craft. Funnel webs are used by burrowing and other types of spiders to move around and stalk prey. Unlike the orbs, they aren't sticky. That allows their creators to move quickly to attack and retreat. Cobwebs and meshwebs, on the other hands, are less structured. These are the ones often found in grassy fields and under rocks, stones and dead leaves [source: University of Michigan].

7. Spiders Go Into Homes in Winter to Escape Cold Weather

wps6BF3.tmp
Photo: James H/Flickr

It's only natural to flee for warmer climes when cold weather strikes. Birds fly south for the winter, grizzly bears hunker down in dens and old folks buy condos in Florida. If you've ever had to wait outside for a bus on a cold winter day, you may find yourself wondering why you left the house at all.

So it would seem to make sense that spiders are more likely to turn up indoors during the cold months. But in truth, most of the spiders found indoors come from a long line of house spiders that have evolved over the years to adapt a life of a constant, temperate climate and poor sources of food and water. These spiders leave their eggs in furniture and other home fixtures. They're actually more likely to be found in large groups during the late summer months, their prime mating season [source: Crawford].

Keeping this in mind, you'll understand why our next myth is also baloney.

6. If You Find a Spider Indoors, Set it Free

wps1D7D.tmp
Photo: Isabelle Adam/Flickr

That's kind of like taking the leash off of your living-room-dwelling dog, giving the old boy a pat on the back and telling him to enjoy his new life of freedom out in the wild. Like pets, zoo animals and newly married husbands, spiders become domesticated pretty quickly. That includes common house spiders who have adapted to like the inside over many generations. You may feel like you're setting the little fella free, but you're probably handing him a one way ticket to a quick ending.

Less than 5 percent of all house spiders have ever been outside [source: Crawford]. Even fewer are adapted to the outdoor life of changing temperatures and conditions, not to mention a whole new world of predators. "Human property rights mean nothing to other species," The University of Washington's Burke Museum arachnid curator Rod Crawford wrote on the museum's website. "There was spider habitat for millions of years where your home is now. My advice is, just wave as they go by."

5. Gigantic, Deadly Spiders Live in Tunnels Under Windsor Castle

wpsD3DA.tmp
Photo: oio154/Wikimedia Commons

Ever hear the one about the royal house spider? Back in 2001, the British press reported that a swarm of venomous spiders invaded the tunnels below Windsor Castle, the countryside residence of England's monarchs. Stories abounded about thousands of the oversized critters - reportedly never before seen, twice as big as an average spider and deadly poisonous - haunting the royals' weekend retreat with jaws and fangs strong enough to puncture human skin.

Those reports were a little inflated, according to Rod Crawford. He explained on the museum's spider myths website that media outlets were misled by uninformed entomologists, professionals who study insects, rather than spiders. Crawford said that once arachnologists (who specialize in the latter creatures) got hold of photos of the Windsor Castle spiders, they quickly identified them as Meta menardi (pictured above), a type of spider found in dark caves and tunnels throughout Britain and most parts of Europe. "Not rare or endangered or dangerous, and only half as big as claimed," he concluded [source: Crawford].

4. Tarantula Venom Will Kill You

wps75E2.tmp
Mexican redknee tarantula. Photo: George Chernilevsky/Wikimedia Commons.

Tarantulas get a bad rap. Sure, you wouldn't want to wake up with one of these bad boys crawling around in your sleeping bag, but their hairy bodies and long, gangly legs make one of the best-known spiders look more vicious than they actually are. If you get bitten by a tarantula it's probably going to hurt a little bit and might make those allergic to the venom slightly uncomfortable, but that's about it.

Tarantula venom isn't considered dangerous, according to the National Institutes of Health. It can, however, cause a variety of allergic reactions. That includes itchiness, redness and puffiness around the eyes, swelling of the lips and throat and - in extreme cases - cardiovascular collapse. For most folks, the venom packs less of a punch than a typical bee sting [source: National Geographic].

Although these spiders feed at night, outdoor campers can rest easy. Tarantulas feast on insects and as well as mice, frogs and even some birds. But not people. They use claws to grab their food and the venom to paralyze the prey before chow time. Tarantulas secrete enzymes which allow them to dissolve their prey's bodies before sucking them in [source: National Geographic].

3. Spiders Are Aggressive

wpsC2A7.tmp
Photo: Lynette/Flickr

People tend to assume that a variety of bumps and blemishes are the work of unidentified spiders who roam their homes when the lights go out and feast on their skin until the morning comes. That's a product of at least two separate myths: One about spiders being naturally aggressive and the other about them being nearby all the time.

Spider bites are actually far less common than many people think. Like most creatures, a spider's natural instinct when trouble arises is to run and hide. That includes hobo spiders (pictured above), those eight-legged critters often found in homes. These poor guys suffer from limited vision and their movements can be misinterpreted as aggression. Even the brown recluse and black widows - two types of spiders whose bites actually can do some damage to humans - are unlikely to sink their teeth into you unless provoked [sources: DeNoon, Scott and Bundle].

The pros say that unless you catch a spider in the act of digging in, the marks on your skin were probably caused by something else [source: DeNoon].

2. The Average Person Swallows Eight Spiders Per Year While Sleeping

wps7C91.tmp
Cambodian fried spiders. Photo: A. www.viajar24h.com/Wikimedia Commons.

Perhaps, we should be looking at this as any easy way to get some nutrition while also catching some zzzzs. People eat fried spiders in Cambodia and, if you scour the Internet, you can find some interesting recipes for battered tarantula. Turns out that if you want to chow down on a spider, you're probably going to have to catch it yourself.

Despite popular belief, it's exceedingly rare for a person to swallow one spider while sleeping, let alone the eight creatures we're said to take down each year. Indoor spiders spend their time staying out of humans' way, either sculpting their webs or kicking back in the dark corners of a room and waiting for lunch to come along. Unless you have bed bugs - which could also be the source of a suspected spider bite - spiders aren't likely to hop in the sack with you. There's no lunch source awaiting [source: Sneed].

That's not to mention the physiological problems with the spider-swallowing myth. A person sleeping with his or her mouth open is probably snoring. The sound of cutting lumber coming out of a large body is probably enough to scare off most spiders [source: Sneed].

1. Spiders Are Always Nearby (3 Feet Rule)

wpsCB94.tmp
Photo: Tarantuland/Flickr

Just like the British royals at Windsor Castle, it's said that common folk are nearly surrounded by spiders. It's been often repeated that spiders are always just 3 or 6 feet (1 or 2 meters) away, depending on your Internet source. But it really depends on where you are. If you're having a picnic in the park or hanging out in your back yard, then you're probably surrounded by tiny spiders. If you're in an airplane or at the top of a skyscraper the nearest arachnid may be miles away. Closer to Earth, golf courses and other turf settings are often spider-free because they're so heavily managed by groundskeepers. Many spiders tend to stay in their burrows come winter, especially in northern areas, meaning they are unlikely to swarm if you step outside for a snowball fight. There's certainly not any hard data out there to make this claim common knowledge [sources: Henriksen, Buddle].

What we do know is that most types of spiders are limited to different parts of the world. Brown recluse spiders, for example, can be found from one side of the U.S. to the other, but rarely move above the Mason-Dixon line. Hobospiders, on the other hand, seem to prefer more moderate climes and are commonly found in northern regions of North America [source: Brown Recluse Spider].

Author's Note: Thanks to this assignment, I now know that the tiny little creature that I caught scurrying across my kitchen floor this morning isn't a spider. I know that because this bug only had six legs. What I don't know is whether that makes the critter more or less likely to bite me or to crawl in my mouth while I'm snoring tonight.

Related Articles:

More Great Links:

Article Sources:
1. Brown Recluse Spider. "Where do Hobo and Recluse Spiders live?" (May 7, 2015)
2. Buddle, Chris. "You are always within three feet of a spider: Fact or Fiction?" Arthropod Ecology. June 5, 2012 (May 7, 2015)
3. Crawford, Rod. "General Fallacies." Burke Museum. (May 3, 2015)
4. Crawford, Rod. "House Spider Myths." Burke Museum. (May 3, 2015)
5. Crawford, Rod. "Myth: Spiders come into houses in the fall to get out of the cold." Burke Museum. (May 3, 2015)
6. Crawford, Rod. "Just Plain Weird Stories." Burke Museum. (May 3, 2015)
7. DeNoon, Daniel. "Is It a Spider Bite? Probably Not." WebMD. (May 3, 2015)
8. Explorit Science Centre. "Spider Facts." (May 3, 2015)
9. Henriksen, Missy. "Debunking Common Spider Myths." National Pest Management Association. Nov. 8, 2012 (May 7, 2015)
10. Kaufman, Rachel. "Tarantulas Shoot Silk From Feet, Spider-Man Style." National Geographic. May 17, 2011 (May 3, 2015)
11. Masta, Susan. "Spiders Commonly Found in Houses." Portland State University. (May 3, 2015)
12. National Geographic. "Tarantula." (May 3, 2015)
13. National Institutes of Health. "Tarantula spider bite." April 24, 2015 (May 3, 2015)
14. Ogg, Barb. "Wolf Spiders in Nebraska." University of Nebraska-Lincoln. (May 3, 2015)
15. Scott, Catherine and Christopher Bundle. "The truth about spider bites: "Aggressive" spiders and the threat to public health." SciLogs. Sept. 4, 2014. (May 6, 2015)
16. Sneed, Annie. "Fact or Fiction? People Swallow 8 Spiders a Year While They Sleep." Scientific American. April 15, 2014 (May 3, 2015)
17. Spider Bite Treatment. "Hobo Spiders." (May 3, 2015)
18. University of Michigan. "Webs and Cocoons." (May 3, 2015)

Top image: Bark jumping spider (Clynotis severus). Credit: JJ Harrison/Wikimedia Commons.

[Post Source: How Stuff Works. Edited. Some images added.]

No comments:

Post a Comment

Please adhere to proper blog etiquette when posting your comments. This blog owner will exercise his absolution discretion in allowing or rejecting any comments that are deemed seditious, defamatory, libelous, racist, vulgar, insulting, and other remarks that exhibit similar characteristics. If you insist on using anonymous comments, please write your name or other IDs at the end of your message.