Spiders:are
one of the most feared and miss-understood creatures of the world, most of it
comes down to bad experiences in the past or bad stories that have had the truth
warped over time. The main image people have of spiders are little things
that produces silk and give poisonous bites, this is not all true!
Yes many spiders do produce silk so now we look into the world of spider silk,
silk is used for a number of things but we will start with building webs and the
different types of webs. Spiders belong to groups to with the type of web they
build and whether they have 6 or 8 eyes.
Webs:
Spiders that spin a web use it to catch food but not all spiders spin webs; we
shall look only at the webs for now.
Lace-web, tube-web, tangle-web, sheet web and orb web; the orbed web is the most
know web and the most common found in the garden especially when covered in
dew. You are most likely to see the sheet web in hedgerows and grasslands, the
tube web is not a commonly seen on due to its nature of being tube shape but you
would see the entrance. Tangle and lace webs you may have seen and not thought
twice about it. A web is used to catch food, a lazy spider’s way of catching
food at that. Next let’s look at catching food.
Food:
The Net casting spider
<Deinopis longipes>
creates a net web that is spread between the front legs and during the night it
uses this to catch anything that walks into it or flies past, it moves with
incredible speed only a high speed camera can show the effects of how it does
this. Other spiders create a burrow and lay trip lines out and when something
trips the line the spider darts out very fast to catch the prey, some even go
hunting strangely section as hunting spiders and they don’t spin a web they only
use silk for the egg sac. Let’s move onto other uses of silk.
Silks
other use:
Silk is also used for protecting the egg sac whether it be on the back of the
spider or secured to a corner, they use silk to cocoon the eggs for safety and
in vast amounts has a yellow tinge to it and normally this is seen around rooms,
lights or around the shed. Silk is also used by spiderlings to leave the house,
securing a strand <dragline to something they use the wind to carry the spider
off to a new place and during early-mid autumn you may well see lines of silk
off the washing line or off a low roof. Adult spiders use a strand to escape
from the web if in danger and they use this to climb back up, adults also use
this to move homes.
This is not really a use of silk more like different type of silks but a spider
can produce different types of silk to make it sticky, non-sticky or even
thicker. A spider uses either one back leg or the back pair to draw out the
silk from the spinnerets; it is not squeezed out as some people think it is.
Spiders also recycle the web by eating it and the body turns this back to silk
later on. Spider also use silk when burrowing, these act as ‘trip’ lines
telling the trapdoor spider that food is outside.
spiders in general: There are so far 40,000 to 45,000 know species of spider and
experts think that there are around another 25,000 to 30,000 species awaiting to
be discovered totalling around with the unknown and know species it could be
around 70,000. Out of the 45,000 know to man only a very small number of
spiders contain venom that effects humans in general, I state in general as some
people could have a reaction to a perfectly harmless spider. The spiders that
have venom effecting humans are classed over 2 categories firstly we have the
less effecting “cytotoxic”
then the more fatal “neurotic”.
Cytotoxic:
Examples of spiders include the brown recluse of the North America and the
violin spider of the South Europe & Africa, the way this venom works is by
“eating” the tissue and muscle around the bite area, this can be extremely
painful and can get infected.
Neurotic:
Examples of spiders include the Black widow of Southern America & other warm
regions and the Red back of New Zealand & Australia. Neurotic works by blocking
the signal from the brain that tells our heart to beat, our lungs to breath
leading into respiratory failure. This can be a long drawn out process or it
can kill within a short time frame.
Most
of the time the venom won’t kill a person as long as they act fast, most
reported deaths today are because people have left it too long to get treatment
or they are too remote to get the help in time.
Other
facts:The
largest of all spiders is the Goliath tarantula of south America with an
impressive leg span of 25 CM and the tiniest is a little fully grown male from a
group called patu digua and its body length 0.37MM witch is smaller than a pin
head. Apart from size spiders have so many cool things about them for example
you have some that are so striking in colour that you need shades on and then
you have the ones so well camouflaged that only movement gives them away, then
you go into the subject of
appearances:
there are the normal looking spiders like a garden spider but out in warmer
regions there are spider like the spiny backed Orb-weaver and the horned
Orb-weaver. Most of the stunning looking spiders belong to the orb family. A
lot of people are unsure of the reason for the shapes, some say to make them
look bigger, and some say its so other creatures trying to eat them can't
because of the horns or spikes. There are also the spider that look like twigs
or even a bird dropping and there are spiders that look like ants the only way
to tell is by the 8 legs this helps them as there feed is normally ants. To
help them avoid danger they blend in with the background e.g. green spiders live
in trees and white spiders live on white flowers this helps them to eat but it
helps stops the spider being eaten. Spiders don't score well in intelligence
and sometimes spider that should blend in doesn’t for example a pinkish coloured
on a white daisy as can be seen in the gallery. There is also the jumping
spider group and here in Britain they are small but when I was in the USA the
jumping spiders were bigger and you can clearly see the 2 front pairs of eyes
that are larger but they still have poor vision, spider use vibration for
everything not lets look at the vibration.
Vibrations:Spiders have extremely poor eyesight and use hairs all over
the body to detect vibrations, these hairs translate smell as well and the hairs
on the bottom of a spider’s foot are extra sensitive to vibrations. In a web a
spider will lay in the hub of the web and lay with legs on trip lines so when
something flies into the web the spider can tell 1) size 2) location 3) friend
of food, with this a spider knows whether to cut its looses and cut the trapped
item free because it could be a leaf or worse a wasp as they can kill spiders.
If it decides the trapped item is food I will go over to it and inject venom and
spin it in silk to make a soup from the body, this it will drink later once it’s
fully dissolved. If it’s a male spider entering the web of a female he will
start plucking lines in the web as a courting procedure, the female can either
accept him or eat him, if she accepts him then they can start to mate but some
females get hungry after sex and will eat the male spider anyway. The black
widow spider will eat her mate during sex and research has shown the male black
widow only released the sperm during the eating process.
bravenet.com