Fascinating Facts About Spiders
Spiders are quite delicate compared to some of their food,
but by using poison the spider can subdue its prey before it
has too much chance to fight back. Spiders have two poison
sacs -one per fang -muscles around the sacs contract, forcing
poison down the hollow fangs and out of the small opening,
at the 'business' end.
The spiders front bit (CEPHALOTHORAX) contains its poison
glands, brain, stomach and muscles. The stomach works by being
stretched wide to 'suck in' food
that has been mashed to a pulp.
The abdomen contains the spider’s heart, lungs, breathing
tubes, gut, silk glands, reproductive organs and waste organs.
The heart pumps its blood around its body.
The seven-sectioned legs are powered by sets of muscles and
blood pressure. At the end of the legs spiders have two or
three little 'claws'. In web spinning spiders one of the claws
helps to hold on to the web. Hunting spiders can have dense,
hairy tufts which help hold their prey -these hairs can be
so fine at the ends that they draw up a little of the moisture
that coats most surfaces (however smooth), effectively sticking
the spiders leg down, which means that these spiders can even
climb up glass.
Spiders have poor eyesight (at best 30cm / 12"). Some
cave spiders have no eyes at all, relying on other senses,
especially the sensitive hairs that cover spiders' bodies.
Tasting hairs are spread over the spiders' body and the legs
and pedipalpi have hairs that can detect tiny movements in
A spider's eyes are on top and near the front of its head.
Different species have different numbers of eyes and the size
and position also varies. Most species have eight eyes, arranged
in two rows of four each. Other kinds have six, four, or two
eyes. Some spiders can see better than others. Hunting spiders
have good eyesight at short distances and their eyesight allows
them to form images of their prey and mates. Web-building spiders
have poor eyesight and their eyes are used for detecting changes
in light. The eyes, and their arrangement, can help identify
• Woodlouse spiders (Dysderidae) have six small eyes
set in a circle at the front of the cephalothorax..
• Jumping spiders have two large, main, eyes facing forward (these
give a focused image) with small, secondary, eyes which
pick up light and movement.
• Money spiders can have their eyes on top of little lobes sticking
up from their heads.
Below the spider's eyes is its mouth opening. Spiders eat
only liquids because they do not have chewing mouthparts. Around
the mouth are various appendages that form a short "straw" through
which the spider sucks the body fluid of its victim.
The spider can only eat some of the solid tissue of its prey
by predigesting it. The spider sprays digestive juices on the
tissue and the powerful juices dissolve the tissue. A large
tarantula can reduce a mouse to a small pile of hair and bones
in about 36 hours by predigesting and sucking.
Pedipalpi are a pall. of appendages that look like small legs.
One pedipalp is attached to each side of the spider's mouth,
and they form the sides of the mouth. Each pedipalp has six
parts. In most kinds of spiders, the part closest to the body
has a sharp plate with jagged edges. The spider uses this plate
to cut and crush its food. In adult male spiders, the last
part of each pedipalp has a reproductive organ.
Spiders can make (up to) six different types of silk from
special glands in their abdomen (spinnerets). Some silk is
for wrapping prey, some for spinning sticky webs, some is used
to make or line a shelter and (females) make some especially
for protecting the eggs.
As soon as a male spider matures, it seeks a mate. The female
spider may mistake the male for prey and eat him, but most
male spiders perform courtship activities that identify themselves
and attract the females. The male of some species vibrate the
threads of the female's web, male hunting spiders wave their
legs and bodies in an unusual courtship dance, jumping spiders
use the coloured hairs on their legs to signal females and
male nursery web spiders present the female with a captured
fly before mating.
Before mating, the male spider spins a silk platform called
a sperm web. He deposits a drop of sperm from his abdomen onto
the platform. Then he fills each of his Pedipalpi with sperm.
He uses the Pedipalpi to transfer the sperm to females during
mating. After mating, the female stores the sperm in her body.
When she lays her eggs, several weeks or even months later,
the eggs are fertilized by the sperm. Females can continue
to lay eggs for many months after mating because of the stored
sperm. Usually, the female does not eat the male after mating
as is commonly believed.