7. Spider Webs

FACTSHEET 7 Spider webs Advancing Arachnology Geoff Oxford Geoff ClassicClassic orborb webweb ofof thethe GardenGarden SpiderSpider AraneusAraneus diadematusdiadematus... Not all spiders build webs to catch their, largely insect, prey but those that do are responsible for some of the most iconic and beautiful structures in the living world. The web descriptions below can’t be (Tegenaria species). In the Oxford Geoff late summer and autumn comprehensive and there is often much males of these species run variation within families. The outlines should, across floors and fall into however, provide an indication of the many baths and sinks in their quest for a female. Females, ways British spiders use silk to detect and and for most of their lives trap their prey. males too, live in little- disturbed places, droplets. These detain any Orb webs constructing a flat sheet of prey which hits the web, The orb web is the structure non-sticky silk with a tubular enabling the spider to strike. children often draw when retreat in one corner. These However Uloboros plumipes, depicting spiders (see cover); webs can outlive their an increasingly common orb- it is made by four spider original builders and be used weaver in greenhouses and families in Britain. In three of and refurbished by several garden centres, produces an the families the silk spirals are generations of occupants. coated with sticky glue orb made of cribellate silk. Prey get their legs and bristles caught up in the Velcro-like Tangled webs strands. These three-dimensional criss-crosses of silk are built Funnel webs by three families of spiders. Funnel-web builders in Britain Perhaps the most familiar should not be confused with example, festooning the the infamous Sydney funnel- corners of rooms and the web spider from Australia back of furniture, belongs to Geoff Oxford Geoff (which is in a completely the Daddy-longlegs spider different family). Our single Pholcus phalangioides, a family of funnel-web spiders species that has rapidly Large house spider Tegenaria contains the, perhaps all too spread north through Britain funnel web familiar, large house spiders over the last 50 years or so. Not all spiders spin webs: Web silk: Spiders can produce many Spiders are unique in the different sorts of silk with distinct way that silk is involved physical properties, and used for a FACT in virtually all aspects of variety of purposes. The familiar orb web their lives. However, of the Garden spider (Araneus FILEalthough spiders and webs diadematus), for example, requires silk are commonly thought of together, only from three separate types of silk gland 17 out of the 37 spider families in Britain during its construction. Some spider build webs in order to catch prey. families produce a woolly, entangling Silk production: Spiders produce silk silk (known as cribellate silk) which proteins in glands deep within their emerges from special glands and which abdomens. It emerges as fine strands of is combed out by rows of bristles on the finished silk from highly mobile, finger- hind legs. like organs (spinnerets), at the rear of the Web types: Broadly, seven different web body. Some insects also produce silk (like architectures can be recognized among the silkworm) but, unlike spiders, their British spiders – orb, funnel, tangled, silk emerges from the mouthparts. lacy, radial, hammock and purse. silk around a central retreat. Helen Smith These are made by the cribellate (lace-weaving) spider, Amaurobius. The spiders shoot out at frightening speeds when the lacy lines are disturbed; they are easily fooled when Hammock web of a money spider the web is touched with a tuning fork or a rapidly Hammock webs vibrating electric These are built by the money toothbrush! spiders (Linyphiidae), by far the largest family in Britain. On a Jenny Strange Jenny cold morning the sheer number of webs, built low down in a grassy field and made visible with dew, is staggering. The web consists of a domed sheet of silk Tangled web of the comb-footed spider Enoplognatha ovata sometimes supported above and below by ‘guy ropes’. The Less noticeable are tangled upper guys help to intercept webs on low vegetation flying insects, which fall down made by the family of onto the sheet, below which comb-footed spiders, the spider lurks. Theridiidae. These spiders are mostly small and Purse webs rounded and sometimes quite colourful. They include The single British species the larger, well-known Radial web of Segestria representing the ‘tarantula’ Noble False Widow spider side of the spider family tree, Steatoda nobilis, which can Radial webs Atypus affinis, occurs largely build a tangled web and Here a number of trip-wires in the south. It builds a also one resembling a radiate out from a central, (usually) sealed, silk tube funnel web. silk-lined retreat, built into a which is part underground and hole or crevice. This is part above and frequently Lacy webs probably the most primitive covered with soil particles. Prey type of web in that it doesn’t walking over the above-ground Almost every wall with serve to entangle but merely portion are seized from within crevices, and dense garden alerts the spider to the prey’s and dragged inside through a conifers, will support an presence. Some species in slit cut in the wall by the spider. untidy mesh of bluish-grey the only British family to Lacy web and retreat of Amaurobius build these webs (Tube Purse web of Atypus affinis Geoff Oxford Geoff spiders, Segestriidae) are NR Hunt large, such as Segestria florentina, which is slowly increasing its range across southern England and south Wales and sports impressive green, iridescent jaws. One striking orb-web weaver is the Wasp spider Argiope bruennichi. This species incorporates a ziz-zag of dense, white silk down the web, the function of which in this species is still not known. Vincent Oates Vincent For more information For fact sheets on some of the species mentioned see: britishspiders.org.uk/factsheets The British Arachnological Society The BAS is Britain’s only charity devoted exclusively to spiders and their relatives. We use science and education to advance the wider understanding and appreciation of arachnids, and to promote their conservation. Find us at: www.britishspiders.org.uk www.facebook.com/BritishSpiders or on Twitter @BritishSpiders actsheet text by Geoff Oxford and Helen Smith, edited by Nicky Rowbottom, designed by Colin Edwards Graphic Design Graphic Edwards Colin designed by Nicky Rowbottom, by and Helen Smith, edited Geoff Oxford by actsheet text F Registered Charity - England and Wales No. 260346, Scotland No. SC044090.

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