How do spiders spin webs?

1. Silk starts as a runny liquid inside the spider. When it is pulled out through tiny nozzles called spinnerets, it turns into a strong, solid thread.
2. First, the spider lets a thread float away on the breeze. When it catches on a twig, she pulls it tight and walks across. This is the bridge line.
3. She drops from the bridge on a new line to make a Y shape. Then she adds frame lines all around the outside, like a picture frame.
4. Next she adds spokes, called radii, from the middle to the frame, like the spokes of a bicycle wheel. They are tight and strong.
5. She lays a temporary spiral from the middle out. Then she walks back in, laying a stretchy, sticky spiral and taking the temporary one away.
6. A fly gets stuck on the sticky spiral. Its buzzing shakes the threads. The spider feels the shaking with her legs and runs straight to it.

Tap each part of the spider and the web to find out what it does.

• Silk glands. Silk glands inside the abdomen make liquid silk. Orb spiders have several kinds of glands, each making a different silk: strong, stretchy, sticky or for wrapping.
• Spinnerets. Spinnerets are tiny nozzles at the tip of the abdomen. As liquid silk is pulled out through them, it turns into solid thread.
• Leg claws. Web-building spiders have a small extra claw on each foot. It grips the silk like a hook, so the spider can walk on her web without getting stuck.
• Vibration sensors. Spiders have special slits in their legs that feel even tiny shakes. With a leg on each spoke, the spider can tell which way the shaking comes from.
• Eyes. Most spiders have eight eyes. Web-building spiders don't see very well, so they rely on touch and vibrations instead.
• Fangs. The spider's fangs bite trapped insects. Garden spiders are gentle with people, and their bite is not dangerous to us.
• Spoke (radius). Spokes are made of strong, dry silk and pulled tight. Shakes travel quickly along them to the spider in the middle.
• Sticky spiral. The spiral is stretchy and covered with tiny drops of glue. It stretches when a bug hits it, so the bug doesn't bounce off, and the glue holds it.

Build the orb web in the right order. Then tap a spoke and tap the spiral. Which shake reaches the spider better?

Experiment: Which thread carries a shake to the spider best: a spoke or the spiral?

1. Build the web: bridge, frame, spokes, then spiral.
2. Tap a spoke and watch the shake travel to the spider.
3. Tap the spiral. Compare the readout.

What we found: Spokes win! They are tight, straight and dry, so a shake races along them to the middle. The stretchy spiral wobbles and soaks up the shake, so less of it reaches the spider.

Turn on JavaScript to try it yourself.

It's foggy and the spider can't see. Feel each shake: if a bug is stuck, tap the shaking spoke. If it's just the wind or a leaf, press Ignore.

Spider silk is made of protein, like your hair. Inside the spider it is a runny liquid. As the spider pulls it out through her spinnerets, the liquid stretches and turns into a solid thread thinner than a hair.

An orb web is built in a set order. First comes the bridge line, carried by the breeze. Then the spider makes a Y, adds a frame around the outside, and fills in spokes from the middle like a bicycle wheel.

Last, she lays a temporary spiral outward and then a sticky spiral inward, eating up the temporary one as she goes. Many orb spiders build a fresh web every day or night, and some even eat the old web to reuse the silk.

The spider waits at the hub or in a hiding place nearby, holding a signal thread. She can't see well, but her legs feel the smallest shake. Bugs that buzz make the web shake differently from wind or a falling leaf.

Key words

Spinnerets

Nozzles at the end of a spider's abdomen where silk comes out.

Orb web

A round, wheel-shaped web with spokes and a spiral.

Radius (radii)

A spoke of the web, running from the middle to the frame.

Capture spiral

The stretchy, sticky spiral that catches insects.

Hub

The center of the web, where the spokes meet and the spider often waits.

Vibration

A quick back-and-forth shaking that can travel along a thread.

Check your thinking

1. What are the tiny nozzles that silk comes out of called?

   Show the answer

   Spinnerets. Spinnerets are at the tip of the abdomen.

2. How does an orb spider find a bug stuck in its web?

   Show the answer

   It feels the vibrations with its legs. Shakes travel along the threads to the spider's legs.

3. What does a spider build first?

   Show the answer

   A bridge line. The bridge line, carried by the breeze, holds up the rest of the web.

4. Why is the spiral stretchy?

   Show the answer

   So a flying bug doesn't snap it or bounce off. Stretching soaks up the bug's crash, and the glue holds it tight.

5. What do many orb spiders do with their old web?

   Show the answer

   Eat it and reuse the silk. Silk is made of protein, so eating the old web saves material for the next one.