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Another important feature of many spiders is their uses for silk and the
making of their webs. There are a total of seven different kinds of
silk glands. Each spider has a minimum of three, with most having
five. Each kind of silk has a different purpose. Some kinds are
sticky while other kinds are dry. Using different kinds of silk and
various spinnerets can bring about different forms of silk. Four of
the forms are: thin, thick, sticky, and dry.11
There are many uses for silk. The most common uses include building
webs, attaching onto stable objects, draglines, wrapping dinner, lining
homes (or burrows), making an egg sack, and ballooning. Some spiders
build a nursery web to guard spiderlings (baby spiders) until they are old
enough to fend for themselves.
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Silk that
is sticky and beaded is used for catching prey. This stick-beaded-silk
making is a technique used by some spiders. It is made by a
pulling-snap reaction that is done with the hind legs. The finished
product is usually used for catching jumping or flying insects. |
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Silk
is also used for ballooning. Ballooning is used by some spiderlings as
a means of transportation. Do you remember in the movie "Charlottes's
Web"? Her spiderlings crawled to the top of the post and let out silk
for the wind to catch. This is ballooning. As the spiderling
faces the wind, the wind blows and threads of silk are unreeled. These
strands of silk are caught by the wind. The wind is able to pick up a
spiderling and carry it for distances of over hundreds of miles to its new
destination. This process explains why spiders are found in the most
remote corners of the world. Islands, atolls and even Mount Everest
cliffs harbor these kinds of spiders.12 |
SPIDER WEBS
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The most recognizable use for silk is spider webs. It's important to
keep in mind that not all spiders are web weaving spiders. Other
spiders are hunting spiders and use their silk for other reasons. Web
weaving spiders are equipped with poor vision and hooked claws. There
is also a special oil on their body that keeps them from getting caught in
their own web. |
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There are
three types of weavers:
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Tangled web weavers |
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Sheet weavers |
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Orb weavers |
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A tangled
web weaver constructs a web that is a shapeless mess of threads. It is
the simplest type of web to make. However, each species of this kind
of web has its own particular pattern. |
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A sheet
weaver constructs a flat sheet of silk between blades of grass or branches.
Some of these types also construct a vertical criss-cross web. When
prey hits the criss-cross, it falls into the sheet and is captured.
This type of web only gets repaired when the need arises. |
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Orb weavers
weave the most elegant of all webs. Although the patterns very as do
the number of species, the basic structure is the same. An orb web is
a complicated structure of 'round-n-round' motion. This web can be
found between branches, flower stems, house gutters...almost anywhere.
Both dry and sticky silk is used. Most orb weavers wait in a hidden
corner until the prey vibrates the web. Orb weavers spin a new web
just about every night. A new web takes about an hour to construct.
If prey or another obstruction puts a hole in the web, the spider will
repair it.13 |
OTHER USES FOR SILK
Different spiders have different uses
for silk.
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The bolas
spider drops one strand of silk that has a drop of sticky silk on the end.
As an insect flies by, the bolas swings the strand with precise aim and
catches the prey. |
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The
ogre-faced stick spider spins a web and holds it open with its four front
legs. This peculiar web can be stretched several times its original
size to catch prey.14 |
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The bowl
and doily spider constructs a web that is horizontal with a rounded, sunken
middle. Around the edge, it is flatter, giving it a "bowl with a
doily" appearance. |
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The purse
web spider builds a sheet web in a burrow form along a tree side. When prey
lands on this web, she crawls up with out being seen and bites through the
web, thereby catching her prey.15 |
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A wolf spider may construct a funnel web. A funnel web is like
a sheet web, but shaped as a funnel. The spider will sit in the
narrowest part of the funnel and then attack when prey lands on any part of
the funnel. |
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The filmy
dome spider builds a dome. It hides underneath the dome until an
insects lands on it. The spider simply pulls it through the web. |
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The
labyrinth spider builds two webs. One web is a tangled web and its
purpose is to hide in it. The second web, an orb web, is built to
catch prey.16 |
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Some orb
weavers include:
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sik spider |
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marbled spider |
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arrowhead spider |
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shaped micrathena spider |
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The most
recognizable orb web of them all is made by the garden spider. This
web can reach two feet in diameter and has a distinguishing zig-zag of silk
that stretches across from one side to the other through the center. |
An interesting note. It should be mentioned that some spider's spin
silk that is stronger than steel of the same width. The best known
spider for this kind of silk is the golden silk spider. Silk from this
spider was used, in some countries, for bags, head dresses, and fishing
nets. Since this was highly uneconomical, the use became abandoned.17
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