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How do spiders make silk?

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Quick answer

Spiders produce silk inside abdominal glands as a liquid protein solution. When they pull it through tiny spigots on their spinnerets, the proteins align, water is removed, and the liquid hardens into a solid fibre. Different glands make different silks for webs, egg cases, or safety lines.

Spiders make silk by pulling a liquid protein solution through microscopic spigots on their abdomen, where it solidifies into a fibre as it is stretched. The silk is stored as a liquid gel inside glands and only becomes solid thread outside the body.

Step by step

  1. Specialised cells in the spider's abdomen make silk proteins called spidroins.
  2. The proteins are stored as a concentrated liquid crystal in silk glands.
  3. The spider pulls the liquid through a narrow duct leading to a spigot.
  4. As it passes through, the proteins align and lose water, solidifying into fibre.
  5. The spider uses its legs or gravity to draw out the thread as needed.

Key things to understand

  1. Silk proteins, called spidroins, are produced inside specialised glands in the spider's abdomen.
  2. The spidroins are stored as a concentrated liquid crystal solution, not as a solid thread.
  3. Each gland connects to a tiny spigot on a spinneret, a movable finger-like structure at the rear.
  4. As silk is pulled out, the proteins align and lose water, turning the liquid into a solid fibre.
  5. Different glands make different silks for webs, egg cases, draglines, or wrapping prey.

Labelled diagram

  1. Silk gland

    Produces and stores liquid silk proteins called spidroins.

  2. Duct

    Narrow tube that carries the liquid silk toward the spinneret.

  3. Spigot

    Tiny nozzle where the silk exits the body.

  4. Spinneret

    Movable structure bearing many spigots for different silks.

  5. Solid fibre

    Silk hardens as it is pulled, forming a strong thread.

How a spider produces silk

Real-world examples

  • A garden spider spins an orb web using stretchy capture silk and stiff radial threads.
  • A jumping spider trails a dragline silk as a safety line while hunting.
  • A female spider wraps her eggs in a tough silk sac for protection.
  • A diving bell spider uses silk to build an underwater air bell in ponds.

Common mistake

✗ Myth: Spiders shoot silk out of their mouths like a spray.

✓ Fact: Spiders produce silk from spinnerets at the rear of their abdomen, not from the mouth. The silk is pulled out, not squirted, and solidifies as it stretches.

People also ask

What is spider silk made of?
Spider silk is made of proteins called spidroins, which are long chains of amino acids. These proteins contain repeating segments that allow the silk to be both strong and stretchy. The exact composition varies between silk types, such as dragline or capture silk.
How do spiders spin webs?
Spiders spin webs by releasing silk from their spinnerets and using their legs to pull and position the threads. They first build a framework of non-sticky radial lines, then add a spiral of sticky capture silk. The process is guided by touch and instinct, not sight.
Why is spider silk so strong?
Spider silk is strong because its protein chains form tightly bonded crystalline regions that resist stretching, while flexible amorphous regions allow it to absorb energy. This combination gives it high tensile strength and toughness, surpassing many synthetic materials.
Is spider silk stronger than steel?
Yes, weight for weight, dragline silk is often stronger than steel and tougher than Kevlar. It can stretch significantly before breaking, absorbing a lot of energy. This combination of strength and elasticity makes it ideal for catching fast-flying insects without snapping.
How do spiders avoid getting stuck in their own webs?
Spiders walk only on the non-sticky radial threads and avoid the glue-covered spiral threads. They also have a waxy, oily coating on their legs that prevents the glue from adhering. When they do touch a sticky thread, they use their legs to carefully detach it.
Can spiders run out of silk?
Yes, spiders can deplete their silk reserves, especially after spinning a large web or laying many eggs. They need time and food to replenish the protein stores. Some spiders recycle silk by eating old webs to recover the amino acids.
Why don't spiders get stuck in their own webs?
The glue droplets are only on the spiral threads, not the radial ones. Spiders step carefully on the non-sticky radials and use their claws to grip. Their legs also have a chemical coating that reduces stickiness.

Part of the guide: Nature & Earth: Living Things and Rocks →