Tela aranea Anhang
What are spider webs made of? And how do they spin them?
[Lisa Hendry]
Find out how web-spinning spiders do what they do and learn about the
impressive, multipurpose material they use to catch their dinner.
Spiders make their webs from silk, a natural fibre made of protein.
Not only does spider silk combine the useful properties of high tensile
strength and extensibility, it can be beautiful in its own right.
Jan says, 'Silk is an amazing material. Golden silk orb-weavers, which
are found in warm regions around the world - but not the UK, unfortunately -
spin webs with a lovely golden sheen. Their silk has even been used to create a
shimmering golden cape that was exhibited at the Victoria and Albert Museum in
2012.'
UK spiders tend to produce silk that is white or has a bluish hue.
There are seven different silk glands, which produce silk with different
characteristics and uses. For example cribellate silk
is very woolly.
Jan Beccaloni, the Museum's arachnid curator,
adds, 'Cribellate silk acts like Velcro, sticking to
the legs and bristles of captured insects.'
Each type of silk gland is associated with a particular spinneret. No
species has all seven, but orb-web weavers have five.
Golden silk orb-weavers (Nephila species Quelle remedia.at) spin silk with
a brilliant yellow colour
How do spiders make their webs?
Spider spinning silk to make its web
A spider spinning silk to make its web, pulling the thread out with its
hind leg
Spiders have structures called spinnerets on their abdomen, usually on
the underside to the rear. These are the silk-spinning organs. Different
species have different numbers
of spinnerets, but most have a cluster.
At the end of each spinneret is a collection of spigots, nozzle-like
structures. A single silk thread comes out of each.
Jan explains, 'Although it looks a bit like an icing nozzle, the silk is
pulled out by gravity or the spider's hind leg. The silk is liquid when it's
inside the spider.'
Before it is extruded out of the spinneret, cribellate
silk first passes through a sieve-like structure called the cribellum.
Spiders that make this type of silk also have a row of specialised leg bristles
called the calamistrum, which combs the silk out and
gives it the different, woolly texture.
Spiders then follow various patterns of activity to construct their
webs, depending on what species it is. It's fascinating to watch.
Do all spiders make webs?
Although webs are the most well-known use for spider silk, not all
spiders make webs to catch their prey. In fact, less than half of the 37 spider
families in Britain do.
Other spiders, such as crab spiders in the family Thomisidae,
are 'sit and wait' predators - for example Misumena vatia lurks on flower heads, waiting to ambushing visiting
insects. Others, such as jumping spiders in the family Saltidae,
actively follow their prey and catch it by leaping on it.
Crab spider on a flower clutching prey
A jumping spider, Salticus scenicus (Quelle: Salvatorapotheke),
attacking a fly
Some spiders even invade other webs to find their food. The pirate
spiders, of which there are four UK species in the genus Ero,
go onto another spider's web and mimic
the behaviour of its prey to lure the spider closer. When the web's
owner investigates, the pirate spider attacks.
Sericum conicum = Seide/= Silk: a
multipurpose material
A jumping spider peers out of its silk cell hiding place
However, even spiders that don't make webs have uses for silk, including
creating moulting platforms, sperm webs for males and retreats.
Jan adds, 'Jumping spiders, for example, make little silken cells in
which to hide in during the day - a bit like a sleeping bag.'
Most spiders use silk to wrap their eggs.
Another common use for silk is as a drag line. Every so often a spider
attaches a thread of silk to something, like an anchor, so that if it falls, it
won't fall too far and can
drag itself back up to the previous position.
Ballooning is another spectacular use for silk, allowing the mass
dispersal of spiderlings and small adults.
After climbing to a relatively high point, the spider points its abdomen
skywards and pulls out one to several threads. When air or electrostatic
currents carry the threads upwards, the spider follows. They can be carried
many thousands of metres.
Field coated in gossamer threads
Money spider mass dispersals in particular make quite a sight. Sometimes
the numbers involved can leave an entire field coated in gossamer threads.
Jan says, 'Not all spiders disperse this way, but it's the reason
spiders are some of the first creatures to colonise new islands.'
More spider web facts
Now that you know how spiders make their webs, discover their impressive
variety. British spider webs can be grouped into seven broad types based on
their architecture: orb, sheet, tangle, funnel, lace, radial and purse. But
even within each group, different species put their own spin on the style.
The diving bell spider (Argyroneta aquatica) probably has the most unusual use for its web,
which enables it to spend most of its life underwater - a unique ability among
spiders. It constructs a net of silk between submerged vegetation and uses it
to gather a bubble of air - its very own diving bell.
View the common styles of web and the spiders that make them.
[Lisa Hendry]
Dusty spider webs are associated with Halloween and creepy houses, but
many are beautiful or architecturally accomplished.
Did you know that you can tell what kind of spider is lurking by the
threads it spins?
A web isn't a foolproof way of identifying the spider that made it, but
its shape will usually allow you to establish which family it comes from, and
it's often possible to be even more specific. Here we outline the main web
structures that UK spiders use to catch their prey and the common architects of
each kind.
Dew-covered orb web
A dew-covered spider web in autumn.
Frozen spider web
A spider
web frozen solid in winter.
Spiders build webs all year round, but autumn is the best time to spot
them outdoors. Morning dew and mist droplets suddenly reveal a multitude of
hidden webs that were previously virtually invisible thanks to the transparent
nature of silk.
Autumn is often thought of as spider season for this reason, and because
spiders tend to be fully grown at this time of year and searching for a mate,
making it more likely we'll see them.
Frosty spider webs also make a stunning sight.
To get a better look at webs when they're not covered in dew or frost,
you can spray a fine mist of water to make their fine details stand out. This
won't harm the spider or damage the web - just make sure you use a clean spray
bottle with no traces of chemicals.
Lightbulb surrounded by a messy spider web
This web will catch insects attracted to the light
Location, location, location
Spiders use their webs to catch dinner.
The choice of location is key to success.
Some spiders build their webs across potential insect flight paths.
High-traffic areas such as near a light or window that's lit up at night are
prime sites.
Other species place webs down low where crawling invertebrates are
likely to wander by and horizontal webs can catch insects if they fall off the
plant they were feeding on.
Types of spider web
British spider webs can be categorised into seven broad types: orb,
sheet, tangle, funnel, lace, radial and purse.
Orb webs
These are the classic, two-dimensional webs that look like bicycle
wheels or dart boards.
Orb webs are constructed with radial threads that function as a
scaffold. The spider then lays down sticky threads in a spiral.
Orb web
Classic orb webs look like a bicycle wheel
Four UK spider families make this kind of web. Three coat the silk with
sticky glue to hold captured prey in place: Araneidae,
Tetragnathidae and Theridosomatidae.
The fourth, Uloboridae, instead spins its web
out of cribellate silk.
Jan Beccaloni, the Museum's arachnid curator,
says 'Cribellate silk is very woolly. It acts like
Velcro, sticking to the legs and bristles of captured insects.'
Garden orb-weaver
A member of the Araneidae family, the garden
orb-weaver or garden cross spider (Araneus diadematus) is probably the best-known orb-web spider. True
to its name,
the garden orb-weaver is very common in gardens throughout the UK, but
it occurs in a wide variety of habitats.
Jan says, 'Its web is a wonderful feat of natural engineering and can be
very large, as much as 40 centimetres in diameter.'
Orb web constructed under a blade of grass
The webs of garden orb-weavers tend to be almost vertical and stretched
across undisturbed spaces that are busy with insects such as flies, wasps and
beetles
Read more
Garden orb-weaver spider on a dew-covered web
Close-up of the garden orb-weaver, Araneus diadematus. The abdomen of this spider is usually well-marked with a
pattern of whitish spots that form a cross.
Females can grow to 1.5cm long.
A new web takes about two hours to build. Step one is to drift a silk
line across a gap on the breeze. After strengthening this supporting strand
with extra threads,
the spider adds the radial and spiral threads. To finish up the web, the
spider removes the central knot of threads and replaces it with a lattice.
Missing sector orb-web
Web of Zygiella x-notata,
with the typical missing sector top left
The spider waits in a head-down position at the centre of the web or
lies hidden among nearby vegetation where it remains in contact by means of a
signal thread.
When an insect flies into the web the spider approaches the source of
the vibrations, bites it and wraps it in silk, to feed on later.
The missing sector orb weaver (Zygiella x-notata) constructs a very similar web, but one sector is
left completely free of spirals. A strong signal thread passes
through this sector to where the spider sits in its retreat. They're
commonly found on the outside of window frames.
Webs spun by Tetragnathidae spiders, the
long-jawed orb weavers, follow a similar pattern to Araneus
webs, but there is a hole in the centre. This is often where the spider takes
up position, spanning the hole with its four hind legs. The webs can be in
pretty much any orientation, not just vertical.
Theridiosoma gemmosum
builds a web derived from the typical orb shape. These small webs have an open
hub and resemble an inside-out umbrella. The species is rare,
found on low-growing plants near water in southern Britain.
Wasp spider = Argiope bruennichi
(Quelle: remedia.at)
Some orb-weaver spiders add decoration to their webs: an extra band of
silk called the stabilimentum.
This is particularly striking in the case of the wasp spider (Argiope bruennichi). It
incorporates a zig-zag of dense, white silk down the
centre of its web. What this is for
still isn't known, but there are a few ideas.
1. Jan explains, 'It's thought that some spiders may use a stabilimentum for camouflage. It may make them harder to
spot on their web. Some spiders even attach the husks
of their digested prey.
2. 'Another popular hypothesis is that the stabilimentum
helps attract insects to the web.
3. 'A third suggestion is that the vivid patterns act as a warning to
large animals, such as birds, that might otherwise accidentally destroy webs in
their path. It looks like
the stabilimentum has different functions
depending on the species.'
When an orb web becomes badly damaged, or loses its stickiness because
of the effects of wind and rain, the spider rolls the threads into a ball and
eats them to recycle
the silk components. This usually happens every day or two.
Diagram showing the triangle web of Hyptiotes paradoxus and how it keeps it taut to snare prey.
Hyptiotes paradoxus
builds an unusual web that has earned the spider its common name, the triangle
spider. If a circular orb web was a pizza, the web of Hyptiotes
paradoxus would be a single slice. The spider also
has quite a distinctive appearance. It is a fairly rare spider, present in
England and Wales but not Scotland.
Jan adds, 'Your best chance of seeing it is likely to be on yew trees in
graveyards.'
Hyptiotes uses its distinctive web as a
snare. The spider sits on a nearby twig and holds taut a thread that runs to
the tip of the triangle. Any prey caught on the web's fuzzy cribellate
silk soon finds itself completely entangled as the spider immediately releases
the thread, turning the web into a net, and then tightens it around its victim.
Garden centre spider
A relatively new arrival to Britain, probably imported on pot plants
from the Netherlands, the feather-legged lace weaver (Uloborus
plumipes) has spread throughout much of the UK over
the past 25 years.
It has set up home in garden centres - where winter temperatures don't
drop below freezing - and so it is often referred to as the garden centre
spider.
Garden centre spider, Uloborus plumipes, on its web
The garden centre spider, Uloborus plumipes, on its cribellate silk
web, which acts like Velcro and stops prey escaping
The orb web of Uloborus plumipes
is similar to that of Araneus diadematus
but usually more horizontal - sometimes across the tops of plant pots - and the
threads are fluffier.
The spider is an expert in camouflage, resembling dried vegetation when
at rest.
Since the web often looks a bit scruffy, it gives the impression of an
abandoned web with dead plant material stuck to it. Even the spider's egg sac
looks like a dead holly leaf.
Researchers studying Uloborus plumipes have shown that cribellate
silk is extremely fine (just a few nanometres thick - much thinner than most
other silk) and the spider electrostatically charges
the threads by combing them with specialist hairs on its hind legs.
Sheet webs
These densely woven, thin, horizontal sheets look like silken hammocks
adorning grass and low bushes. Bugs fall onto the hammocks or get knocked down
when they collide with a tangle of threads above the sheet.
Jan says, 'The sheer numbers of sheet webs visible on a dewy morning can
take your breath away.'
Holly bush covered in lots of sheet webs
Dew revealed a multitude of sheet webs on this holly bush
Sheet web on a gorse bush
Sheet webs collect insects that fall onto them from above
Sheet webs are usually built by the Linyphiidae. This is the largest
family of spiders in the UK, with 280 species. It includes the tiny money
spiders said to bring good luck if you find one wandering over you.
The smallest species tend to build their sheet webs on depressions in
the soil, others on low vegetation and some on tree bark.
The money spider hangs beneath its web, waiting for dinner to land
above.
Tangle web
A tangle web built by the daddy-long-legs spider
Like their name suggests, these webs look like a messy tangle of
threads. They're often found in houses and collect dust as they age.
Although they look like haphazard constructions, they're still effective
at catching prey. These 3D webs are built by four families of UK spiders: the Dictynidae, Pholcidae, Theridiidae and Nesticidae (a
single species).
There are seven species of Dictynidae spider
in the UK. They create small, tangled meshes of cribellate
silk, often building them over flower heads and under leaves, and also among
leaf litter.
Daddy-long-legs spider
Pholcus phalangioides
is the member of Pholcidae you're probably most
likely to encounter, as it has become increasingly familiar as a house spider
in Britain.
Fifty years ago it was quite rare here. A prolific breeder, it is now
becoming very common, spreading northwards and living in centrally heated rooms
all year round.
Pholcus phalangioides
is a pale, delicate spider with long thin legs that hangs upside down on its
flimsy, untidy web in the corners of rooms or behind furniture. If disturbed,
the spider bounces up and down and becomes a blur.
It makes a good houseguest, consuming woodlice and other unwanted
household pests. It also eats large spiders.
Daddy-long-legs spider
Pholcus phalangioides
is a dainty looking spider
© LFRabanedo/Shutterstock.com
Daddy-long-legs spider with large house spider prey
Despite its puny appearance, Pholcus phalangioides can take on large house spiders and win.
Image courtesy of McZul (CC0), via Wikimedia
Commons.
Noble false widow spider on its web
The noble false widow spider, Steatoda nobilis, on its messy tangle web
© thatmacroguy/Shutterstock.com
False widow spiders
The comb-footed spider family, Theridiidae,
includes the much maligned false widow spiders (Steatoda
species). Their webs are loose 3D frameworks of criss-crossing sticky threads.
Steatoda webs are usually found in
buildings, sheds and garages or nearby under stones, in walls and garden fences.
Two of the most commonly observed species are the noble false widow (Steatoda nobilis) and the
cupboard spider (Steatoda grossa).
By day, Steatoda nobilis
hides away in a silken retreat. This more densely woven section looks a bit
like a funnel. From dusk onwards, it hangs upside down on its untidy web, which
it usually builds at high level. This non-native spider prefers south facing
aspects and conservatories.
The native Steatoda grossa
prefers to make its messy web in dark corners among clutter in garages and
sheds. It characteristically hangs or moves about this web upside down.
Funnel webs
They're made by just one family in Britain - the Agelenidae
- which includes the labyrinth spider (Agelena labyrinthica) and house spiders (Tegenaria
species). The overall shape resembles a funnel.
Living low down among grass, brambles, gorse or heather, the labyrinth
spider typically spins a large sheet of closely woven silk that extends from a
long tubular retreat at the rear.
Funnel web
A funnel web built among vegetation
© Saharadesertfox (CC-BY-SA-3.0), via
Wikimedia Commons
Labyrinth spider on its web
Labyrinth spider with prey at the entrance to its funnel web
© Tony Mills/Shutterstock.com
House spiders
Despite their name, house spiders can be found outside around hedges,
rock faces and rabbit burrows, not just in houses. However, these do tend to be
the spiders
that unnerve us when they come dashing across our floors or become
trapped in our baths - particularly in autumn when males go looking for a mate.
Some, including Tegenaria atrica,
Tegenaria gigantea and Tegenaria parietina, grow
particularly large - with legs spans of around eight centimetres, and as much
as 17 centimetres in T. parietina.
Tegenaria species on its large web built on a
rock face
House spiders live outside as well as in buildings. Their funnel webs
can include large sheets of silk as well as a tubular retreat. The webs can
become very dusty.
House spiders spin large sheets of closely woven silk which funnels into
a long tubular retreat at one edge. If their web is at the entrance to a hole,
they just produce a collar of silk rather than a large sheet.
Several generations of spiders can refurbish the webs and they can
attain considerable size and dustiness in an undisturbed cellar, shed or
garage. These are what people often think of as cobwebs.
Lace webs
Amaurobius spider and its lace web
Lace webs are similar to funnel webs in that they also have a tubular
retreat where the spider hides, but they are made of 'woolly' cribellate silk and the threads are more loosely spaced,
looking more like lace than a silk sheet.
Only three species of lace web spider live in the UK. They all belong to
the genus Amaurobius.
The webs are often spread out flat around gaps on walls, fences and
window frames - particularly those of Amaurobius similis and A. ferox, while A. fenestralis webs tend to occur on dense vegetation like
gorse, under stones and around cracks in tree bark.
Radial webs
This style of web has single lines of silk radiating away from a silken
tube. The lines function as trip wires that alert the spider hiding inside the
tube to prey wandering past. It dashes out at frightening speed.
Unlike most other types of web that entangle prey, this one simply
alerts the spider to its presence. They hunt nocturnal insects such as moths
and cockroaches, as well as bees and wasps.
Only a single family of UK spiders makes this kind of web: Segestriidae, which only has three species living in
Britain.
Jan says 'This family has a unique leg arrangement. The hind legs hold
on to the inside of the tubular retreat and the other three pairs face forward,
touching the radial threads.'
Radial web
The trip wire threads are clearly visible on this radial web
© crabchick (CC BY 2.0), via Flickr
Tube web spider in its web
A tube web spider waits on the radial web it has built in a hole in a
wall, ready to pounce on prey
© David Short (CC BY 2.0), via Wikimedia Commons
Tube web spider on a log
The shiny green jaws are clearly visible on this tube web spider
© Luis Miguel Bugallo Sánchez
(CC BY-SA 3.0), via Wikimedia Commons
Read more
Tube web spider
The tube web spider (Segestria florentina) is the largest of the UK species of Segestriidae, with females growing more than two
centimetres long. The spider is black or dark brown. The base of its jaws
(chelicerae) are often a striking iridescent green.
Although restricted to southern England and Wales, mainly around old
ports, reports suggest this originally Mediterranean species is spreading
further inland.
These spiders tend to like living in crevices in old walls.
'They sometimes even excavate a bit of the old masonry to make a hole in
which to spin their tubular web,' adds Jan.
Purse webs
Only Atypus affinis
builds this type of web and is known as the purse web spider.
This spider is the only tarantula relative in the UK. Its fangs are
orientated differently from those of other UK spiders, projecting downwards.
Purse web lying on the ground covered in soil
The long silk tube of this purse web is covered in soil and debris,
camouflaging it
© Marshal Hedin (CC BY-SA 2.0), via Flickr
Purse web spider
The purse web spider, Atypus affinis, is the UK's only tarantula relative
© Federico Crovetto/Shutterstock.com
Atypus affinis
digs a long underground tunnel and lines it with silk. The long silk tube has a
usually sealed end that extends above ground, where it lies on the top of soil
at the base of grass, looking a bit like a sock or purse. This part of the web
becomes well-camouflaged by soil and debris.
This is part of the spider's cunning hunting strategy, explains Jan:
'The spider hangs upside down inside the sock shape. If anything crawls
across the outside, the spider reaches through and grabs hold, piercing the
tube wall and the victim with its fangs. It then drags the subdued prey through
the web into its lair and repairs the hole.'
Find out about silk and how spiders spin their webs >
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