Spider webs: not just for Halloween
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.
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.
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.
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.
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.'
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.'
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.
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.
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.
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.
'Another popular hypothesis is that the stabilimentum helps attract insects to the web.
'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.
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 unlucky 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.
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.
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.'
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.
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.
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.
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.
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.
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.
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 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.
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.'
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.
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.
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.'
What are spider webs made of?
Spiders make their webs from silk, a natural fibre made of protein. There are seven different silk glands, which produce silk with different characteristics and uses. Each type of silk gland is associated with a particular spinneret. No species has all seven, but orb-web weavers have five.
Not only does spider silk combine the amazing 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.
How do spiders make their webs?
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.
Silk: a multipurpose material
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.
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.
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.
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.'