The Coolidge examiner., 1934-03-02

titblts into the snare.
The dome-shaped web is better
suited for catching insects rising
from the ground In flight. as many
do about dusk or In the morning.
Irregular net webs, haphaZard
tangles OF threads OF all lengths, are
spun by that annoyer OF housewives
in all temperate climates. the COM
mon house spider. and by many
other species. Once considered
primitive, such webs now are re-
garded as degenerate. They prob
ably represent an evolution from
the sheet type, altered TO decrease
resistance to the wind. and 10 fa-
cilItate mendlng. AS fy-traps, they
are effective and. In addition. usd-
ally serve well for rearing the brood
OF spIderlings
Like human fishermen. many spi-
der species have found that a plane
net Of two dimensions is not only
economical OF weight and materials
but Ideal for landing a catch. The
orb web. built on this principle. may
be put In exposed places. where
prey Is most plentiful, since with its
open construction II offers little re-
slstance TO the wind.
Suspended from framework OF
stout base lines and carefully
spaced to permit freedom Of move
ment In spinning its threads form
wheel-like design of maximum
strength with minimum Of material.
The spider sits at the hub, ready
| instantly to detect a shared victim
| and pounce upon Ii. In the net-snare
method OF catching prey the orb
web Is the spiders last word. Few,
II any, other animals, human or
subhuman, have equaled 1t.
Although the most symmetrical
web ever made by spider is not
really perfect. according to human
standards, scientists marvel at the
accuracy with which angles and
distances are measured"
1
Method Of Construction.
The spider starts her geometrical
web with perimeter lines connect
ing objects around space large
enough for her purpose. From
these lines she suspends few
| threads which converge at the CEN
ter of the future web. Now begins
the process Of spacing the radil. She
| attaches the end of new radius
AT the center and runs along a spoke
already laid down. spinning out the
| silk for the new one as she goes.
When she reaches the perimeter
| line she takes a fixed number OF
steps along it and attaches the new
thread. This process is repeated
until all the desired radii are in
place.
If the foundation lines should
chance to form wheel rim accu-
rately circular, the distance be-
tween spokes would be equal; but.
since the perimeter is usually an ir-
regular quadrangle and never cir
Gle. the spacing varies somewhat.
The spiral turns of silk, which
! complete the net, are more accurate
ly spaced than the radii. since the
spinner lays down each new turn
with her foreleg touching the last
one. Thus the length Of the forelegs
and the size of the spider deter
mine these distances.
Scout stepping" and the use
Of the "leg ruler are instructive
In spiders. Even when Isolated
from it's kind from the moment OF
its birth a spiderlng will produce
exactly the same web design as
its mother and in exactly the same
manner.
Spiders constitute a large clan
of some $4,000 described species. al
though most abundant and diversi-
fed in the Tropics, they range far
into the Arctic regions. and are
found almost anywhere that earth
ly conditions will sustain life.
Far up on Mount Everest, above
the highest plant life, at an eleva-
tion of $1,000 feet, spiders have been
found living among the wind-and-
snow-swept rocks. Thus they are
the loftiest permanent inhabitants
of the earth.
Some spiders, such as the trap
door makers, occupy only restrict
ed area; while others, such as orr
common house spider. are found In
many lands and all the continents.