|Outdoors spider spin a web known as the
orb, a masterpiece of symmetry.Using abdominal pressure,
the female spider forces silk to flow outwards, initially
attaching one end of the first strand, the bridge, to
an object, etc. Dropping the strand, she runs across the
ground to another high spot, pulls the strand tight and
attaches it firmly in place with a spit of sticky glue
from another gland.
Once the first horizontal strand is fixed, the
spider drops two plumb lines of silk, one at either end and
construct a second bridge lower down to form a framework.
Within the framework, she spins a series of radii with a hub
at the center. Only the outer radius is coated with sticky
globules of a substance produced by a specialist organ called
the amputate gland. Once she is done, shell deposit
more sticky globules at intervals on the other radii, leaving
spaces to step between.
As a final touch, she spins a warning strand of silk between
the nest and the radius closest to the hub of the web, so
when something lands, the strand vibrates. She then hurries
to the center of the web along the untreated warning strand.
Spider has poor eyesight, so they need to rely on other senses
to determine the size and strength of the prey. If the victim
is a deadly, poisonous insect; the strand may be cut off.
If its large, like a wasp or hornet, the spider will
squirt silk at it from a safe distance. Then the spider can
make its approach slowly via the spaces she has kept free
of sticky globules
on the web strands. If she accidentally step on a sticky globule,
her body will produce an oily secretion that acts as chemical
thinner, enabling her to free herself.