Spider silk is:

• Strong enough to stop a speeding bullet;

• Elastic enough to stretch many times its length;

• Able to absorb moisture to stay flexible;

• Useful in healing wounds;

• Capable of stopping a 747 flying at full speed!

Investigate the secrets of this amazing substance:

Spider Silk
Electron Micrgraph

Look at Silk

Spider silk is a protein. When it is inside the spider's body it is a liquid. When the spider releases silk from the spinnerets, it becomes a solid.

Molecules in the liquid link together to become a very large molecule called fibroin. A strand of spider silk is actually made of many threads, sometimes thousands, released together.

Spider Silk (from left): Normal, Stretched 5x, Stretched 20x

Spinnerets

Spiders have special spinning organs called spinnerets located toward the back and under their abdomens. These spinnerets are so small that the Electron Microscope is required to see them clearly.

Spiders have from one to four pairs of spinnerets. The typical spider has three pairs of spinnerets.

The Cribellate spiders make a special kind of woolly silk. The woolly silk is pulled out by combs on the fourth pair of legs. The photo shows the cribellum, which spins the woolly silk.

Make Artificial Silk

Wouldn't it be wonderful if scientists could produce a synthetic spider silk? So far, this task has not been accomplished, but they are working on it! Here are some possibilities for its uses:

• Artificial tendons and ligaments;
• Surgical sutures;
• Bulletproof vests;
• Space Station coatings.

In the past people have tried to harvest silk from spiders in large enough quantities to market, but this has proven unprofitable.

Unlike silk worms, spiders will not live peacefully in large groups and close together. They are predators who will eat their neighbor if they have the opportunity.

Besides, it has been estimated that it would take 1.3 million spider egg cases to produce 2.2 pounds (1 kilogram) of silk.

Nexia Biotechnologies: "Biosteel"

A company in Canada, Nexia Biotechnologies, has put the spider silk gene into the mammary glands of goats. These bioengineered cells produce a silk protein that is very close to real spider silk. Then, the silk protein is removed from the milk and spun into fibers. The result is an "artificial" silk as tough as dragline silk, but weaker and more stretchy. The company is calling this genetically engineered silk "Biosteel." Its quality may already be usable for medical sutures (or even fishing line!) that "self-destructs" after a period of time!

Other Spider Silk Research

Companies such as DuPont are studying spider silk structure with the hope of synthesizing it. Using a computer simulation and recombinant DNA technology, "biosilk" was produced by inserting spider silk genes in yeast and bacteria, the protein produced, dissolved in a solvent, and then spun into fibers using the spinning style of a spider.

Scientists at different universities such as LSU, University of California and Cornell are researching the molecular structure of spider silk. Understanding how the amino acids in spider silk align will perhaps enable scientists to reproduce it successfully.