Spider silk is one of the most impressive materials in nature. Weight for weight, the strongest silks are tougher than Kevlar (used in bulletproof vests) and more elastic than nylon. A web the width of a pencil could theoretically stop a Boeing 747 in flight. Spiders produce this material from special glands in their abdomen and construct complex, precise structures with it.
Types of silk
Most orb-weaving spiders (the classic web-builders) produce several types of silk for different purposes. Dragline silk forms the outer frame and spokes — it's the strong, non-sticky structural silk. Capture spiral silk forms the sticky spiral that catches prey — it's elastic and coated in tiny droplets of glue-like liquid. The spider walks on the non-sticky radial threads; only insects blundering into the sticky spiral get caught.
Building a web is like constructing a suspension bridge, then draping a sticky fishing net across it. The bridge (the radial threads) bears the structural load and stays put. The net (the spiral threads) catches what you're after. The spider runs on the bridge; the prey gets caught in the net. Except the spider builds both in under an hour, from materials it produces inside its own body, using only eight legs and no blueprints.
How does the spider build it?
The spider starts by creating a "bridge" thread — it lets out silk that catches the breeze and attaches to a distant surface, or walks the silk across deliberately. This becomes the top of the frame. It then adds more frame threads, creates the radial spokes from the centre outward, and finally spirals the sticky capture thread inward from the outside. The whole process in a garden spider takes 30–60 minutes.
Do spiders stick to their own webs?
No — because they walk on the dry, non-sticky frame threads rather than the sticky spiral. They also have special leg-tip structures that reduce contact area with silk, and some species have an oily coating on their legs. They're not immune to their own glue by magic; they just know where to step.
Spider silk is amazing stuff. It's one of the strongest materials in nature. The strongest spider silk is tougher than the material in bulletproof vests. It's also stretchier than the stretchy materials in tights. A web as thick as a pencil could stop a jumbo jet flying. Spiders make this silk inside their bodies using special parts.
Types of silk
Spiders that make round webs use different types of silk. Frame silk makes the outside edges and straight lines like spokes on a bike wheel. This silk is strong but not sticky. Sticky spiral silk makes the curvy spiral that catches bugs. This silk is stretchy and covered in tiny drops of glue. The spider walks on the straight spokes that aren't sticky. Only flies and other insects get stuck in the gluey spiral bits.
Building a web is like making a climbing frame and then hanging sticky tape across it. The climbing frame holds everything up and stays strong. The sticky tape catches what you want. The spider runs along the climbing frame bits. The bugs get caught on the sticky tape bits. But the spider builds both in less than an hour. It makes everything inside its own body. It only uses its eight legs and has no plans to follow.
How does the spider build it?
The spider starts by making a bridge thread. It lets silk blow in the wind until it sticks to something far away. Or it walks the silk across like a tightrope walker. This becomes the top of the frame. Then it adds more frame threads around the edges. It makes straight spokes from the middle going outwards like a bicycle wheel. Finally it makes the sticky spiral going round and round from outside to inside. A garden spider takes 30 to 60 minutes to do this.
Do spiders stick to their own webs?
No, they don't get stuck. They walk on the dry frame threads that aren't sticky. They don't walk on the gluey spiral bits. Spiders also have special feet that don't touch much of the silk. Some spiders have oily stuff on their legs too. They don't have magic powers to avoid getting stuck. They just know where it's safe to walk.