Page 90 - The Miracle in the Spider

90 THE MIRACLE IN THE SPIDER

he spider web is made up of load-bearing frame threads and spiral
capturing threads laid over these and coated with a sticky
T substance, as well as threads binding all the threads together. The
spiral coated sticky threads are not completely tied to the scaffolding
threads. In this way the more an insect caught in the web struggles, the
more it gets stuck to the web. As the capturing threads stick all over the
insect, they gradually lose their elasticity, both growing stronger and
stiffening. In this way the insect is trapped and immobilised, and can be
violently cut up. After this the prey, held by the unyielding scaffolding
threads, like a wrapped-up, living food parcel, has no alternative but to
wait for the spider to come and deal the final blow.

The Web's Shock Absorbency

In order for spiders' webs to be an effective trap, it is not enough for
them to be adhesive or to be made of threads with different characteristics.
For example the web must be designed in such a way as to catch insects in
flight. If we compare the insect caught in the web to a guided missile, just
stopping the insect will not be sufficient. The prey caught in the web must
be rendered immobile, so that the spider can come and examine and bite it.
Catching a missile and immobilising it is no easy task.
The threads which make up the web are at the same time both strong
and elastic. But the level of elasticity of the web is different in different
areas. This elasticity is important for these reasons:
o If the level of elasticity of the threads were less than required, an
insect flying into the web would bounce back the way it had come, as if
hitting a hard spring.
o If the elasticity of the threads were more than required, the insect

would over-stretch the web, the sticky threads would adhere to each other
and the web would lose its shape.
o The effect of the wind has also been allowed for in calculating the
threads' elasticity. Thus a web stretched by the wind can resume its
previous form.