Page 83 - The Miracle in the Spider

The Miracle of Silk 83

weight swing free again. The results of these observations have
established that all this is done by the spider with the aim of
strengthening the web. 28

The Most Pitiless Trap in the World
Prey caught in a spider's web can do little about it. The trap is
prepared so expertly that, as the victim struggles, the web loses elasticity

and grips the prey even tighter. As a little time passes and the victim
becomes completely powerless, the web grows stronger and tauter than
before. In this way the spider, watching the creature's hopeless struggle
from a corner somewhere, can easily kill the trapped prey, which is now
exhausted.
What one would expect when a victim gets stuck in a web is that, as
the insect struggles, the web is pulled out of shape and the creature
escapes from the trap. But exactly the opposite happens and the web
grows stronger, completely immobilising the insect. How can a web
increase in strength as the victim caught in it struggles?
The answer to this emerges when we examine the structure of the
web. The spider's capturing threads take on a new form due to the
moisture of the air. The change happens like this. The garden spider's
spiral threads are formed by the coming together of two liquid-covered
fibres. This adhesive liquid is produced in a different gland from those
which produce the basic fibres. The silk threads which emerge from the
spider's spinning glands are continuously coated in a film of this sticky
material. The source of the adhesive nature of this material is the
glycoproteins it contains. Furthermore, it consists of 80 percent of that

economic material, water. 29
As the sticky liquid comes into contact with the water in the air it
separates into tiny drops which attach themselves to the thread like little
beads. Contracting and stretching the sticky thread in rapid succession
wind and unwind the core fibres inside the droplets. Thus, the entire
system of core fibers and coating is always under tension, keeping the