Spider webs are made from silk. And silk is made from something scientists call “proteins.”
Proteins are special chemicals made by a living thing, like an animal or a plant. You have lots of them in your body. Proteins usually have a certain job to do.
Some join together to make something bigger. Your hair and your nails are made of proteins. They are both made by a protein called “keratin.”
Insects and spiders make silk in a special part of their body called a gland, and use their legs to pull it out of their bodies. This is called spinning. Most species of spider have more than one kind of silk gland. Each one has a different strength and stretchiness and is used for a specific purpose such as making web frames and sticky strands, or covering the eggs. The strength and stretchiness of silk depend on the way the spider’s body arranges the silk proteins.
Spiders have evolved to spin very strong silk webs so they can catch insects to eat. This means that long ago , spiders that made stronger webs caught more insects to eat and had more babies. Spiders that made weaker webs caught fewer insects and had fewer babies.
After millions of years of this process, some spiders today make silk that is very strong. We don’t usually notice just how strong they can be because they are amazingly thin. But the strongest silk, such as silk from a golden orb spider, is actually stronger than steel. Even more
amazing, it is about 50 times as light.
Actually, spider silk is a bit like a cross between steel and rubber. Even with the help of complicated machines and chemicals, humans still don’t know how to make a material this strong, stretchy and light. Spiders are still the champions at this.