My Fascinating Backyard: Spiny Backed Orb Weaver Spider + Spider Myths
by Dani Johnson
March 29, 2013
Photo taken by Mkullen
The other day I almost walked into a spider web that contained a spider that looked bizarre and like nothing else I've ever seen. Its back is white with face-like black markings and it has 6 red spikes around the edges. A lot of people call this little guy a Spiny Backed Orb Weaver, but when I first saw it I called it the Bowser spider. The resemblance to this villain is uncanny and I almost expect to see a fly-ified version of Mario zipping along trying to stomp on Bowser's head. Instead of shooting fireballs Bowser would shoot streams of venom, his castles would be filled with spider webs and the ghosts would be of the flies that perished long ago in those webs. This is coming really close to a recurring nightmare I had as a teenager where a spider king would send his army to abduct me and take me underground to his lair. Maybe I played too many video games as a kid, but this makes me the princess, right? ;) Luckily, as scary as the Spiny Backed Orb Weaver looks, it's completely harmless to humans.
Check out this YouTube video where the spider is crawling around playfully on a plastic cup lid. I can't say that I'd be brave enough to let it climb on my fingers, though!
Spiders are in the phylum arthropoda, which means they are invertebrates that have an exoskeleton, a segmented body and jointed appendages. They have those scary looking jaws called chelicerae and they have fangs to bite prey with to deliver the venom that will paralyze it so the spider can wrap it up to eat later. Most arthropods have extensor muscles that contract and extend their muscles, but spiders have to use hydraulic pressure to extend their limbs. Spiders also have spinnerets on the tip of their abdomen that extrude silk to make webs with. The female Spiny Backed Orb Weaver constructs its web every single night to make sure that the web is secure. The shape of this web is the very reason why the spider is called an Orb Weaver, because it is in a circular pattern rather than a funnel shape, a sheet-like shape or a cobweb. The female usually stays by herself with the web and up to three males will each hang from a single string very close by. The web is usually close to the ground and angled specifically to catch prey such as beetles, moths, mosquitoes, and small flies. Spiny Backed Orb Weavers, like most spiders, are beneficial to humans because they prey upon many small things that we call pests and it is best to simply leave them alone and let them do their business. They are completely harmless and generally do not bite unless specifically provoked, and even if they did bite someone it won't be anything serious.
Check out this neat YouTube video of a Spiny Backed Orb Weaver building its web:
These little guys also come in all sorts of shapes and colors. Here are just a few different marking variations:
Gasteracantha dalyi Pocock, 1900 from Wayanad
Image by Amos T Fairchild
Image by Akio Tanikawa
Image by Sandilya Theuerkauf
Taken at Kadavoor, Kerala, India
Since many people are afraid of spiders it's easy to believe some of the things that one hears passed around without giving it a second thought. Some myths and misconceptions highlighted by Rod Crawford, Curator of Arachnids, at Burke Museum include:
Myth: All spiders make webs.
Fact: While all spiders make silk, not all spiders use it to make a web that is specifically made to catch prey. Some spiders, such as the Wolf Spider, actively hunt for prey and only use the web as a drop line, for an easy retreat, or to build egg sacs.
Myth: The orb shaped web is the only shape spiders make.
Fact: There are actually four different types of webs: orb webs, sheet webs, funnel webs and cobwebs. The orbs are usually easy to see because they are large and usually at a height that humans are likely to walk into.
Myth: Spiders suck the blood from their prey just like vampires.
Fact: Spiders will vomit digestive fluids onto their prey to soften it up so they can chew it up easily with their chelicerae so they can suck it back into their tiny mouths. This isn't always finished in one sitting and spiders will often come back to the body multiple times before they are ready to throw out the remains, which are usually only small bits of indigestible leftover gunk.
Myth: The daddy-longlegs has the world's most powerful venom, but fortunately its fangs are so small that it can't bite you.
Fact: There are three different creepy-crawlies that we call daddy-longlegs: The Harvestmen (which isn't actually a spider), the Crane Fly (also not a spider), and the Pholcid spider. The Harvestmen and the Crane Fly have absolutely no venom at all and the Pholcid spider possesses venom, but it isn't even harmful to humans (like most spider venom) because it isn't designed to harm something as big as we are. After all, a spider's prey needs to be feasibly digested by that single spider — not the huge amount of spiders that one human would feed!
Myth: "Camel spiders" in Iraq are huge monster spiders that are insanely fast and scream like banshee.
Fact: This myth started as a mass e-mail and it turns out that the attached photo takes advantage of forced perspective to make this 5cm long spider appear to be around 40cm long. This myth also includes other false claims such as:
Myth: You can identify Brown Recluse spiders by a violin shape.
Fact: There are way too many spiders that have shapes on their bodies that look like violins for this to be accurate. Not to mention, brown recluse spiders are only found in one region of the US and all other sightings are misidentification. The best way to identify the spider is to get a close up look of the eyes because the eyes of the brown recluse are arranged in 3 sets of 2 rather than 2 rows of 4. This is why it is important to have a spider sample with you to determine for sure that it was a brown recluse (or even a spider at all) that is the cause of the bite. This is no easy task, though, because most of us don't even realize there has been a bite until hours later. There are many times when a person has been bitten by something and a doctor just assumes it is a spider. Some doctors even go as far as saying that they can tell a Brown Recluse spider bite apart from any other bite without having definitive proof (i.e. having a spider sample). These bites affect each person differently and not all bites get seriously infected. Not to mention, general practice doctors study diseases of the human body rather than venomous bug bites, so the advice they are able to give is going to be limited. It must be stressed that there is absolutely no evidence that these spiders exist outside of the area already mentioned, and even then most spiders don't bite people because they aren't after us as prey. However, for people who live in this zone (like me), there are certain precautions that you can take to assure that you aren't bitten, because even though it is unlikely, it does happen from time to time and there are some easy things to do to reduce one's risk.
by Dani Johnson
@Skeptoid Media, a 501(c)(3) nonprofit