How do spiders make silk? Spiders turn liquid proteins into solid fibers with a specialized spinning system.
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Short answer
Spiders make silk from proteins inside their bodies. The proteins begin as a thick liquid in silk glands in the spider’s abdomen. As that liquid moves through tiny tubes and out through structures called spinnerets, it changes into a solid thread. The spider then pulls and places the thread with its legs.
That is why a spider can make a web, an egg case, a safety line, or a small silk shelter without carrying a spool of thread around.
Where does spider silk come from?
Spider silk starts in special glands in the abdomen, the back section of a spider’s body. Those glands make silk proteins. Different glands can make different kinds of silk for different jobs.
For example, one kind can make a strong safety line, often called a dragline. Other kinds can help make the framework of a web, wrap prey, protect eggs, or create the sticky catching thread in some orb webs.
How does liquid become a thread?
Inside the gland, the silk material is a concentrated liquid. It travels through a long, narrowing duct. Along the way, conditions inside the duct help the proteins line up and form a fibre. The spider’s movement and the pulling action at the end also help draw the material into a thread.
The finished silk comes out through tiny nozzle-like openings called spigots on the spinnerets. Spinnerets are the movable silk-spinning structures near the end of a spider’s abdomen.
So a spider does not simply spray a ready-made string. Its body makes the protein material, changes it while it travels through the silk system, and draws it out as a fibre.
Do spiders use just one kind of silk?
No. Many spiders can make more than one kind. The exact number varies by species, and not every spider makes the familiar round web.
Some silk is dry and strong. Some is stretchy. Some web-building spiders also make a sticky, glue-like material that helps catch insects. Spiders use silk for more than catching food: they can use it for egg sacs, shelters, movement, and a line of safety if they fall.
Do all spiders make webs?
All spiders make at least some silk, but not all use it to build a prey-catching web. A jumping spider, for example, may use silk for a shelter or a safety line instead of a large web. A spider can be a silk-maker even if you never find a web in its corner of the garden.
Why do spiders pull the silk with their legs?
Silk does not always come out as a finished thread by itself. Spiders can attach a tiny amount of silk to a surface and then move away. Their legs, claws, and body movement help draw the material from the spinnerets. That pulling helps create and place the thread exactly where it is needed.
Is spider silk stronger than steel?
This comparison needs care. Some spider silks are very strong for their weight and can stretch a long way before breaking. But “stronger than steel” is too simple because strength depends on which kind of silk, which kind of steel, and what property is being compared. Spider silk is impressive because it combines strength, lightness, and stretchiness.
How do spiders make silk in everyday terms? They produce a liquid protein, move it through a specialized duct, and pull it through spinnerets to form a fiber. For context, read Why do spiders make webs? and Do spiders sleep?.
How do spiders make silk when they need a safety line? They can release dragline silk and pull it into place. How do spiders make silk for an egg sac? The same basic protein-spinning system produces a softer wrapping fiber. How do spiders make silk for a web? They switch among several silk types as the web takes shape.
Questions this article also answers
Do spiders ever run out of silk?
Spiders can make more silk, but producing it takes energy and materials from their bodies. They do not have an unlimited supply ready at one moment.
Why do spiders make webs?
Many spiders use webs to catch prey. Others use silk in different ways, such as building shelters, protecting eggs, or making a safety line.
Can people make spider silk?
Scientists are studying ways to make materials based on spider-silk proteins. Making a fibre that behaves exactly like natural spider silk is difficult because a spider’s spinning process is highly specialized.