How Do Spider Webs Work?

Different kinds of spiders build all sorts of different webs, from beautiful bug-catchers to protective egg sacs to clever trap doors. Learn about them in this episode of BrainStuff, based on this article: https://animals.howstuffworks.com/arachnids/spiders-spin-webs.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
brain Stuff, Lauren Vogel bomb here. Greek mythology tells of
a mortal seamstress named Arachne. Her extraordinary talent was matched
only by her ego, and in a moment of pure hubris,
she challenged the goddess Athena to a high stakes weaving contest,

(00:23):
and suffice it to say that this didn't go well
for Arachne. After the showdown, she was transformed into a spider.
At least she got to keep her hobby. Many spiders
are famously good weavers, using materials that can be stronger
than steel. The eight legged critters spin all kinds of
different webs, some big, some small. If you look at

(00:45):
the tip of the abdomen on any given spider, you'll
find one to four pair of tiny stubb like appendages.
Those are the spin a rets, the organs that dispense silk.
Each one is connected to special gland is located inside
the abdomen. Said glands create protein rich liquids that are
squeezed out of spigots, which are microscopic openings in the spinnerets.

(01:09):
Upon exiting the body, the liquids solidify and become silk.
Mind you, not all spider silks are created equal. The
chemical composition of silk dreads is highly variable, and sometimes
it can be altered before the pre silk liquids get
a chance to harden. A plus, by tensing or relaxing,
spigots can change the thickness of the silken fibers that

(01:33):
they release. Alone, spider may have dozens, hundreds, or thousands
of spigots all working together in concert, producing silks with
lots of different consistencies. One of the better known families
of spiders are the orb weavers, encountered on every continent
but Antarctica. Their ranks include around three thousand, five hundred

(01:54):
species worldwide. Individual or weavers can generate eight to nine
different types of silk to protect their eggs. For example,
the arachnids bundle them up in woven sacks with a
layer of nice, soft silk at the center, but spider
silk also comes in firmer, tougher varieties. Or weavers create
dartboard style, vertically oriented webs that most people think of

(02:17):
when they hear the term spider web. Think about Charlotte's
web before she added missives like some pig. We're talking
about the spiral little beauties you've probably seen in countless
backyard gardens. Construction begins after an or weaver makes its
bridge thread. This is the first line in a new web,
usually a lightweight strand that the spider uses to forward

(02:40):
the gap between two firm objects of like tree limbs, rocks,
or window sills. Our exoskeletal pal waits at one end
of the divide and lets this thread drift in the
wind until it makes contact with the other side. When
that's done, the bridge thread is secured at both ends
and reinforced with additional lines of silk. The bridge thread

(03:01):
is the first third of a woven triangle. The so
called frame threads are built in all three corners of
this structure. Together with the major lines on the triangle sides,
they create attachment platforms for a set of very tough
threads known as radii, extending outward from a point at
the center of the web that is the hub. The

(03:22):
radii look like the spokes on a bicycle wheel. Next,
a silken spiral is woven around the hub, covering much
of the radii. Some orb weavers will repeat this process
after building an initial spiral out of non sticky silk,
they replace it with a sticky threaded substitute. A completed

(03:42):
web is a multifaceted tool. When another creature gets ensnared
in one, vibrations and the silken threads convey information about
its size and whereabouts. Spiders use this information while approaching
their victims. Also, researchers have discovered some orb weaver webs
attract flying insects by a static electricity. One species, the

(04:05):
garden center spider, creates these by weaving breads that get
electrically charged with the arachnid rubs its legs on them. Afterwards,
some portions of the web become more adhesive. But why
should or weavers have all the fun? Spiderwebs come in
more than a hundred and thirty known shapes, many of
which look pretty far removed from the iconic or weaver design.

(04:28):
For example, numerous spiders weave horizontally oriented sheet webs, and
sometimes the setup includes an overhanging layer of disheveled breads
that intercept unwary flying insects. Here the ideas for the
victim to collide with one of the upper threads and
then fall down onto the sticky sheet below. However, sheet

(04:50):
webs might play a more active role in prey capture.
Study indicated that moths are attracted to the big horizontal
webs of the lace sheet weave a subtropical Asian spider
because it uses highly reflective silk. Since the molds can't
see very well, entomologists think that the winged critters might
be mistaking these clusters of luminous threads for well lit

(05:13):
forest clearings. Another common type of spiderweb is the much
maligned cobweb sewn by black widows and some related species.
Cobwebs don't come in well organized geometric patterns. On the contrary,
they're messy looking tangles of silk that tend to be
found underneath protective covers like roofs, rocks, or branches. And

(05:37):
then we've got spiders that don't even bother with webs.
Wolf spiders and crab spiders have no need for them
because these free ranging arachnids can usually out muscle their
prey without using any silken traps. Likewise, tarantulas forego the
web weaving process, although they have been known to line
their burrows with silk in order to keep unwanted dirt

(05:59):
from umulating and other species use silk in creative projects.
Trapdoor spiders mix it with dirt and vegetation to create
movable lids for their underground homes, and the aquatic diving
bell spider builds portable webs underwater and uses them to
trap bubbles of oxygen. Furthermore so, I just recently learned

(06:21):
that the peculiar webs actively pull oxygen out of the
surrounding water, much like the guilds on a fish. Today's
episode is based on the article spiders can spin webs
of silk stronger than steel on how stuffworks dot Com,
written by Mark Mancini. Brain Stuff is production of iHeart

(06:43):
Radio in partnership with how stuffworks dot Com and is
produced by Tyler clang Or More podcasts my heart Radio,
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