Spiders are some of the most interesting creatures in the world. These arachnids have tons of things that make them unique, including the ability to spin webs. But what are spider webs made of, and can all spiders create it? Keep on reading to find out!
Spiders use silk to spin their webs and the silk, in turn, is a combination of proteins. This mix of proteins varies between species and gives each type of silk its own properties. Thus, there are different kinds of webs, some to catch prey, some to lay eggs, and some for other purposes.
But in which part of a spider’s body is the silk? What’s the process behind spinning a web? We have the answer to all your questions below!
Everything You Need to Know About Spider Webs
Spider Webs Are Only the Tip of the Iceberg
First of all, a spider web is a collection of silk filaments woven together to create a larger structure. The design of this final structure will depend on its purpose. Although all spider species produce silk, not all of them use it to construct webs. That said, all spiders weave their silk in one way or another and for various reasons.
Think of it this way: Each filament of silk is like a single thread. Spiders can use the “thread” to build a fishing net, create a piece of fabric, or produce a rope.
“Traditional” spider webs and cobwebs are the ones you find between twigs in nature. You can also see these webs in the corner of that room you haven’t cleaned in a while, and they are like fishing nets. How so? Because these webs are traps built for catching food.
You’ve seen it a million times on National Geographic. A spider creates a tightly knitted, almost invisible network of filaments between branches. Then, the patient spider waits for an unsuspecting moth to fly into the trap, get tangled in it, and become dinner.
Yes, spider webs are the most noticeable way (to humans) that spider weave their silk. But webs are not the most common way in which spiders use their silk-weaving capabilities.
Some spiders can weave intricate homes known as funnels. These horizontal funnels are on the ground and function as a sort of maze. Vibrations caused by prey stepping on the trap triggers the spider to attack.
The spider then drags its prey to its chamber at the labyrinth’s center.
By far, the most common way a spider uses its silk is to create draglines or safety lines. These safety lines anchor the spider to a secure place while it hunts or moves around.
This rope-like cord is the strongest type of silk spiders can produce. Draglines can support the spider’s full weight!
Draglines are also useful if a spider falls off a branch or needs to exit without hurting itself.
These single silk lines can also help the spider find its way back home and sense its prey. If an unaware insect trip on the line, the spider can feel the vibration.
Creating egg-sacks to protect their precious ones is another use for spider silk. Spider egg sacks are usually hard and waterproof and keep the eggs warm and safe from predators. These cases last until the babies hatch.
Some male spiders can also carry their sperm in a silk sack. The males keep the sacks ready to implant into females during mating. And they say romance is dead!
Sperm sacks aside, the most peculiar way in which some spiders can use silk if for may be ballooning. As it turns out, some species are excellent at paragliding and can use their silk to weave a sail.
This parachute-like structure catches the breeze and sends the spider through the air. Sometimes, the spider can soar for hundreds of miles at a time. Arachnids use this unique ability to spread all over.
What Are Spider Webs Made Of and How Is Spider Silk Produced
As we mentioned above, spiders make their webs with silk, which at the same time is a combination of proteins. But how does it work?
Well, it all begins in the glands. These special organs are on the lower side of the abdomen. Glands are where spiders store the raw materials for silk-making.
The name of the fluid used in silk production is “dope,” and contains the main proteins for producing silk. Gel-like dope moves from the glands to the storage sack, which will hold it until the spider requires it.
Solidification of dope into a solid protein fiber happens at the tapering duct. At this stage, the spider is ready to expel the silk through the spinneret. The spinneret has lips that clamp the fiber and control its thickness.
Most spiders have three pairs of spinnerets, but some have one, two, or four. Spinnerets can work both independently and in concert to create different silks.
How Many Types of Silk Can a Spider Produce
Now that we know spiders use their silk to produce more than only webs, how many types of silk can they make?
There are discoveries about molecular properties of the wonder that’s spider silk often. Scientists say there are at least seven types of silk so far. Each silk has its features depending on the gland producing it, its purpose, and the species.
For example, silk used for encasing eggs tends to be hard and, when it dries, have a paper-mache-like texture to it. Meanwhile, traditional spider webs used for hunting have to be sticky and flexible. And the silk used for ballooning has to be light and wind-resistant.
So there are seven types of silk-producing glands, but no spider has all seven. Most male spiders have three or even four, and females have an extra one, especially for egg sacks.
The different types of spider silk are:
- Swathing silk: Produced in the achniform gland, the purpose of this type of silk is to wrap caught prey.
- Major dragline silk: The major ampullate gland produces this silk, and it’s the strongest type of spider silk. The purpose of this substance is safety lines and ballooning.
- Minor dragline silk: Produced in the minor ampullate gland, it is about 50% weaker than major dragline fibers. This silk is for horizontal motion, and it helps spiders finding their way back.
- Attaching threads: Produced by the pyriform gland, this silk anchors or supports other threads, sort of like beams to a roof.
- Sticky fibers: Produced in the flagelliform gland, these are the main prey-catching fibers. Thus, these fibers are on traditional orb webs.
- Adhesive coating and droplets: The aggregate gland produces these filaments. The purpose of the droplets is to provide an extra layer of stickiness to existing fibers.
- Egg sac silk: Produced only by females, these sacs’ function is to protect the eggs.
The Different Types of Spider Webs
While not every spider spin webs, about half of all species do. The technique varies from one spider species to another.
Yet, all fall web-spinning methods fall more or less in the five different types of spider webs are:
1. Orb Web
The first type that comes to our collective mind when someone mentions the words “spider web” is orb webs. This classic design is a marvel of natural engineering. Usually built at night, this type of web starts as a mere rectangle-shaped silk frame.
Then, several lines of sticky threads (called radii) cross onto a central hub. Plus, several spirals of extra sticky threads joined to the radii. If an unsuspecting insect crashes onto it, vibrations alert the spider. Dinner is ready!
2. Cobwebs or Tangle Webs
Popular in attics and barns across the nation, these are among the most types of spider webs. Unlike the aesthetically pleasing orb web, cobwebs look kind of messy and irregular.
The structure of cobwebs consists of a bunch of threads supporting a layer of sticky fibers. The sticky fibers on the outside catch the prey and the vibrations alert the spider.
3. Sheet Webs & Dome Webs
These tend to be between twigs or blades of grass and consist of a single flat sheet-like web. The weaving pattern is more random, and only a few of the threads are sticky.
4. Funnel Webs
Larger spiders are the ones that build funnel webs most of the time. These funnels are a structure of non-sticky silk with a tunnel in the middle that leads to a chamber. Think of it as a maze!
As with all the other web types, when prey stumbles onto the threads, the funnel sends vibrations. When the spider senses the pulse, it comes out and drags its victim down the funnel.
5. Triangle Web
A Hyptiotes genus specialty, this one looks a bit like an orb web but instead of a spiral shape, it’s a triangular one.