Spidipedia

01What is a spider?

Spiders are arachnids in the order Araneae. They share their class (Arachnida) with scorpions, mites, ticks, and harvestmen, but they're the only arachnids that can spin silk from their abdomens. If you remember nothing else: insect = six legs and three body parts; spider = eight legs and two body parts.

There are around 52,000 described species of spider worldwide, organised into about 130 families. New species are still being named every week. The British list is more modest at roughly 670 species, of which about a dozen are routinely encountered indoors and another twenty or so are common in gardens.

Despite the reputation, fewer than 30 species in the entire world have venom that meaningfully threatens humans. None of them are British natives. The British arachnological situation is, to use a technical term, fine.

02Anatomy

A spider's body has just two regions, joined by a narrow waist called the pedicel. The front section is the cephalothorax (or prosoma) — fused head and thorax — carrying the eyes, fangs, palps, and all eight legs. The rear section is the abdomen (or opisthosoma), which holds the silk glands, lungs, gut, heart, and reproductive organs.

Legs and how they move

Each of the eight legs has seven segments. Crucially, spiders extend their legs using hydraulic pressure, not muscles — they only have flexor muscles, the bend. To straighten a leg, they pump fluid into it. This is why a dead spider curls up: the pressure goes, and only the flexors win.

The four pairs of legs are numbered I to IV from the front. The two short appendages flanking the fangs aren't legs at all — they're the pedipalps, which act as feelers, food-handlers, and (in males) sperm-transfer organs.

Fangs

The biting apparatus is the pair of chelicerae, each ending in a hollow, curved fang. There are two engineering schools: orthognathous spiders (tarantulas, trapdoor spiders) point their fangs straight down like daggers; labidognathous spiders (almost everything you'll meet in Britain) work them sideways like pincers. Venom flows through a duct from glands in the cephalothorax.

Eyes

Most spiders have eight simple eyes arranged in two rows on the front of the cephalothorax. The pattern is so consistent it's used in identification. Two are usually larger and forward-facing — the principal eyes, providing detail. The others (secondary eyes) detect motion and have a reflective layer (tapetum) for low light. A few families have six eyes, a couple have two, and some cave-dwelling species have none at all.

Spinnerets

At the very back of the abdomen are the spinnerets — usually six, sometimes four, articulated like little fingers — through which silk is extruded. Each spinneret has dozens of tiny spigots, each fed by a different gland producing a different kind of silk for a different job.

03Silk — the wonder material

Spider silk is a protein — a fibroin very similar to silkworm silk but with quite different mechanical properties. It's stored as a liquid in glands inside the abdomen and pulled out through the spinnerets, where shear stress and water loss cause the protein chains to align and crystallise into a fibre. The transition from liquid to solid happens entirely outside the body.

By weight, spider dragline silk is five times stronger than steel and tougher than Kevlar — meaning it absorbs more energy before breaking. A pencil-width strand could in theory stop a Boeing 747. (No-one has tested this. Yet.)

Different silks for different jobs

Most spiders produce five to seven different silks, each from its own gland:

• Dragline silk — the lifeline trailed behind every walking spider; also used for the spokes of orb webs.
• Capture silk — sticky, stretchy, often beaded with droplets of glue.
• Cocoon silk — soft and protective, used for egg sacs.
• Wrapping silk — broad ribbons used to swaddle prey before eating.
• Attachment silk — tough cement for anchoring webs to surfaces.
• Aciniform silk — a fine wrapping silk for prey or sperm webs.
• Pyriform silk — used to glue draglines to surfaces.

04The webs

About half of all spiders don't build webs at all — they hunt actively, ambush, or stalk. Of the half that do, the architecture varies enormously and is one of the best ways to identify a spider family at a glance.

Orb webs

The classic two-dimensional wheel, with radiating spokes and a sticky spiral. Built almost entirely by the family Araneidae (which includes Webster, the garden spider) and the related Tetragnathidae. Constructed in 30 minutes to an hour, usually at dusk or dawn. Many orb-weavers eat the old web each morning to recycle the silk proteins.

Sheet webs

Flat horizontal sheets with a tangle of "knockdown" threads above them. Insects fly into the threads, fall onto the sheet, and the spider — waiting beneath — bites through the silk. The money spiders (Linyphiidae) are the most numerous British spider family, and these are their work.

Funnel webs

A flat sheet leading into a tubular retreat. The spider sits at the mouth of the funnel and rushes out when the sheet trembles. The house spider (Eratigena/Tegenaria) builds these in cellars, garages, and behind furniture; the dramatic Australian funnel-webs (different family entirely) are unrelated.

Cobwebs

The seemingly chaotic three-dimensional tangle made by the family Theridiidae, which includes the false widows and the common house cobweb spider. The chaos is the trap — sticky droplets on certain threads catch crawling insects, and the slightly elastic structure pings them up off the floor.

The strangest webs

• Bolas spiders swing a single sticky droplet on a thread, like a fishing weight, to catch moths attracted by a chemical lure that mimics moth pheromones.
• Net-casting spiders hold a tiny stretchy net between their front legs and throw it over passing prey.
• Diving bell spiders spin domed webs underwater and fill them with air carried down on body hairs.
• Triangle spiders build tiny triangular sails of silk and release the tension when prey lands, springing the structure forward to entangle it.

05Hunters without webs

Web-building is iconic, but it's only one strategy. The other half of spiders are wandering hunters with their own remarkable adaptations.

Jumping spiders (Salticidae)

The most charismatic family by some distance — small, alert, often colourful, and with the best vision of any spider. Their two large forward eyes can resolve detail comparable to a cat at the same distance, and they can see in colour, including ultraviolet. They stalk prey, calculate the leap, and pounce — sometimes from many times their body length away. They trail a safety dragline so a missed jump isn't fatal. The British Salticus scenicus, the zebra spider, is a familiar sight on sunny walls.

Wolf spiders (Lycosidae)

Ground-runners with powerful eyes, especially the two large rear-facing ones. They chase prey across the ground rather than ambushing. Females carry their egg sacs attached to the spinnerets and, later, the spiderlings on their backs — sometimes a hundred at a time. Pardosa amentata is the most common British species, found in lawns, meadows, and gardens.

Crab spiders (Thomisidae)

Sit-and-wait ambushers, often on flowers. Their first two pairs of legs are much longer than the rear two, giving them a crab-like stance and grip. The flower crab spider Misumena vatia can change colour over a few days to match yellow or white flowers.

Pirate spiders (Mimetidae)

These remarkable creatures hunt other spiders. They tap on the edge of a rival's web, mimicking trapped prey, then attack the owner when she comes to investigate. Tiny but deadly to their fellow spiders.

Spitting spiders (Scytodidae)

The British Scytodes thoracica spits a glue-and-venom mixture from its fangs at prey, pinning it to the surface in a zig-zag pattern. Found mainly in old houses in southern England.

06Senses

Most spiders are nearly blind by mammalian standards — their secondary eyes detect light, dark, and movement, but little detail. The exceptions are jumping spiders and (to a lesser extent) wolf and lynx spiders, which need vision for active hunting. For most species, the world arrives through other channels.

Vibration

Hairs on a spider's legs (trichobothria) detect air movement; pressure-sensitive slits in the cuticle (slit sensilla) detect substrate vibration. A web-building spider can tell the difference between a struggling fly, a falling leaf, a courting male, and a strong gust of wind — all by the frequency and pattern of vibration travelling through her silk. She effectively turns her web into an extension of her sensory system, the way we extend ours through fingertips.

Taste and smell

Spiders taste through specialised hairs on their legs, palps, and chelicerae. They can identify prey species, detect pheromones from potential mates, and, in some species, follow chemical trails left by other spiders.

Hearing

Spiders don't have ears in the conventional sense, but recent research has shown that some — including jumping spiders and the ogre-faced net-caster — can detect airborne sound via their leg hairs. They can hear up to about 3 metres away. This was a complete surprise to arachnologists, only confirmed in 2016.

07Venom & the bite

Of the 52,000 known spider species, only the Uloboridae family (around 270 species, all foreign) are completely without venom; they wrap prey in silk so thick it suffocates. Everyone else has venom — but venom is calibrated for the spider's normal prey, and most spiders eat insects. Vertebrate-affecting venom is the exception.

Worldwide, around 30 species have venom of medical concern to humans. The headliners are:

• Australian funnel-webs (Atrax robustus and relatives) — produce a neurotoxin that affects primates including humans. No deaths since antivenom became available in 1981.
• Brazilian wandering spiders (Phoneutria) — large, aggressive, sometimes hitch rides in banana shipments.
• Widow spiders (Latrodectus) — the black widow and relatives. Their venom contains alpha-latrotoxin.
• Recluses (Loxosceles) — produce a tissue-damaging venom; bites can leave necrotic wounds.

The British situation

There are no native British spiders that can seriously injure a healthy adult. The noble false widow (Steatoda nobilis), established in southern England since the 1870s, is the most concerning resident — its bite can cause localised pain and swelling, occasionally with systemic symptoms, but is comparable in severity to a wasp sting. Documented serious reactions are rare, and almost always attributable to secondary bacterial infection rather than the venom itself.

About a dozen other British species can technically penetrate human skin (the woodlouse spider, the cardinal spider, the missing sector orb-weaver, etc.), but bites from any of them are extremely uncommon and produce nothing more than transient discomfort.

If you are bitten

Wash the bite with soap and water. Apply a cold compress to reduce swelling. Take a paracetamol if it hurts. Seek medical attention if you experience unusual symptoms (severe pain spreading from the site, fever, nausea, muscle cramps, or signs of infection over the following days). Don't try to capture the spider; a description is enough. Don't apply old remedies like sucking, cutting, or tourniquets — they make everything worse.

08Lifecycle

Spider lifecycles vary by family, but the broad shape is consistent: hatching from an egg, growing through a series of moults, reaching sexual maturity, mating, and (for the female) producing the next generation.

Egg sacs

Females produce silk-wrapped egg sacs containing anywhere from a handful to over a thousand eggs depending on species. Some carry the sac with them (wolf spiders, nursery webs); some attach it to the web; some hide it in a retreat and stand guard. Spiderlings hatch inside, undergo their first moult, and then emerge.

Ballooning

Many spiderlings — and some adults of small species — disperse by ballooning: climbing to a high point, releasing several silk threads, and being lifted by air currents and atmospheric electric fields. Ballooning spiders have been collected at over 4,500 metres altitude and 1,500 km from the nearest land. Charles Darwin watched them land on HMS Beagle hundreds of miles offshore.

Moulting

Spiders grow by shedding their exoskeleton, typically 5 to 9 times over their life. Mature spiders generally don't moult further, except for some long-lived species. Moulting is dangerous — the spider is briefly vulnerable and can die if interrupted or if conditions are wrong.

Mating

Males are usually smaller than females and considerably more nervous, with good reason. The male spins a small sperm web, ejaculates onto it, then loads the sperm into the bulbs at the tips of his pedipalps. He then seeks a female — sometimes following her dragline silk, sometimes ballooning huge distances.

Courtship is elaborate and family-specific: jumping spider males perform vibratory dances and waving displays; orb-weaver males pluck the female's web in a specific pattern to identify themselves as a suitor rather than dinner; nursery web spider males bring a silk-wrapped gift to occupy the female's fangs during mating.

Lifespan

Most British spiders live one or two years. Females tend to outlive males. The longest-lived spider on record — a wild Gaius villosus trapdoor spider in Australia — was at least 43 years old when she died in 2016, killed by a parasitic wasp.

09What they eat

Almost all spiders eat live prey, predominantly insects. They subdue prey with venom, wrap it in silk if necessary, and then digest it externally — pumping digestive enzymes into the prey through the bite, then sucking out the resulting soup. They cannot eat solid food, only liquid.

The total mass of prey consumed annually by the world's spiders is staggering: estimated at 400 to 800 million tonnes, comparable to the total biomass of human meat consumption. The world's spiders are the planet's largest insect-control service, by some margin.

What's on the menu

• Flies, mosquitoes, midges — the bread and butter of most web-builders.
• Other spiders — pirate spiders, some jumping spiders, and Pholcus all happily eat their relatives.
• Small vertebrates — large tropical species occasionally take frogs, lizards, even small birds and bats. A 2020 review documented 46 spider species worldwide eating snakes.
• Pollen and nectar — many orb-weavers consume pollen trapped in their webs while recycling the silk. The Central American Bagheera kiplingi is the only known mostly-vegetarian spider, eating specialised plant structures called Beltian bodies.

How long they can fast

Spiders have astonishingly slow metabolisms. A house spider in a corner can survive for several months without food. Garden spiders survive autumn lulls between flushes of prey. Cave-dwelling spiders may go years between meals.

10Where they live

Spiders are found on every continent except Antarctica, and in almost every conceivable habitat: rainforest canopy, grasslands, deserts, freshwater ponds, intertidal rocks, caves, mountain summits at 5,000 metres, your kitchen.

British habitats

• Houses and outbuildings — Eratigena and Tegenaria house spiders, Pholcus phalangioides, the missing-sector orb-weaver Zygiella x-notata, false widows.
• Gardens, parks, and hedges — garden spider Araneus diadematus, common cross-spider, garden orb-weavers, jumping spiders on sunny walls.
• Grassland and heath — wolf spiders, money spiders (vast numbers), labyrinth spider, nursery web spider.
• Woodland leaf litter — woodlouse spider, ground spiders, harvestman cousins.
• Wetlands and ponds — water spider Argyroneta, fishing spiders Dolomedes, swamp spiders.
• Caves and cellars — cellar spiders, cave-adapted Linyphiidae.

11UK species you'll meet

Britain has roughly 670 spider species, but the great majority are tiny money spiders living quiet lives in grass. The ones a person actually notices are a much smaller cast.

12The house spider question

The big indoor spiders you see in autumn — the ones that startle you in the bath or sprint across the carpet at 9 pm — are almost always male giant house spiders (Eratigena atrica, formerly Tegenaria gigantea) on the move, looking for females. They've spent the summer as adolescents in cracks behind furniture; now mature, they leave their funnels to find a mate. The "spider season" is real, and it peaks from late August through October.

Are they harmless?

Yes. Bites are vanishingly rare and produce nothing worse than a brief sting. They have very poor eyesight and panic in open space, hence the running-and-stopping behaviour that looks alarming.

Should I put it outside?

This is the difficult bit. Tegenaria and Eratigena spiders are genuinely synanthropic — they've lived alongside humans for so many centuries that British populations are essentially indoor specialists. Putting one outside in autumn often means it dies of cold within days. If you genuinely cannot live with one, put it in an outbuilding or shed rather than the open garden.

The kindest course is to leave it alone. They eat flies. They mostly stay out of sight. They live two to four years. They are, in their unobtrusive way, model lodgers.

13Foreign visitors

Spiders arrive in Britain regularly as accidental imports — usually in fruit shipments, packing materials, or container freight. Most cannot survive a British winter and don't establish populations. A few have, and the climate is making it more likely that more will.

The famous fruit-shop visitors

• Brazilian wandering spiders (Phoneutria) — periodically arrive in banana shipments. Genuinely venomous. Reports of one in your bananas tend to be sensationalised; actual confirmed instances are perhaps once or twice a year nationwide, and the spider is removed by trained pest controllers.
• Huntsman spiders (Heteropoda) — large, fast, harmless. Occasionally arrive in tropical fruit. They look terrifying and want nothing to do with you.
• Brown widow (Latrodectus geometricus) — has been recorded in UK ports but has not established.

Established non-natives

• Noble false widow (Steatoda nobilis) — first recorded in Torquay in the 1870s, probably from the Canary Islands or Madeira. Has spread north steadily and is now common across England, with records in Wales and southern Scotland.
• Mediterranean false widow (Steatoda paykulliana) — occasional, mainly southern.
• Tube web spider (Segestria florentina) — Mediterranean origin, well-established in coastal southern England since the 19th century. Glittering green fangs.
• Daddy long-legs spider (Pholcus phalangioides) — originally subtropical, now ubiquitous in heated buildings across Britain.

14Predators & parasites

Despite the venom and silk, spiders sit firmly in the middle of the food web. Their predators and parasites are numerous.

Predators

• Birds — swallows, swifts, blue tits, robins, and especially the spotted flycatcher all eat large numbers of spiders.
• Other spiders — pirate spiders, jumping spiders, and many species that simply blunder into stronger neighbours' webs.
• Mammals — shrews, hedgehogs, and bats take spiders. House mice will eat them too.
• Reptiles and amphibians — frogs, toads, slow worms, and lizards hunt them.
• Insects — assassin bugs, mantises (where they coexist), and large beetles.

Parasitoids — the horror show

Several wasp groups have evolved to specialise on spiders. Spider wasps (Pompilidae) sting a spider into paralysis, drag her to a burrow, lay an egg on her body, and seal her in alive — the larva eats her from outside while she's still alive but cannot move. The British Anoplius nigerrimus hunts wolf spiders in this way.

Even more sinister are the ichneumon wasps that lay eggs on a living spider's abdomen. The larva drinks the spider's haemolymph through a small hole. Just before pupating, it injects a chemical that causes the spider to spin a special, sturdy web — a web specifically designed to support the wasp's cocoon — and then the larva kills the spider and pupates inside the structure she has just built for it.

In short: nature is metal.

15Records & extremes

• Largest by leg-span — Goliath birdeater (Theraphosa blondi), South America, up to 30 cm. About the size of a dinner plate.
• Largest by body length — also the Goliath birdeater, around 12 cm. Eats frogs, mice, occasionally small birds.
• Smallest — Patu digua, a Colombian midget, around 0.37 mm. You could line up a thousand on a 30 cm ruler.
• Oldest — a wild trapdoor spider in Australia, "Number 16", at least 43 years old when she died in 2016 from a parasitic wasp.
• Highest altitude — Himalayan jumping spider (Euophrys omnisuperstes) found at 6,700 metres on Mount Everest.
• Deepest — cave-dwelling spiders in Croatia at over 1,000 metres below ground.
• Largest web — Darwin's bark spider (Caerostris darwini) of Madagascar, building orb webs across rivers up to 25 metres wide. Her silk is the toughest natural material known.
• Most venomous (per dose) — Sydney funnel-web (Atrax robustus), Australia. No human deaths since 1981.
• Largest British — cardinal spider (Tegenaria parietina), 14 cm leg-span. Lives in old buildings in southern England, including Hampton Court.
• Smallest British — various money spiders under 1 mm.

16In human culture

The spider's place in human imagination is singularly large. Few creatures have inspired so many myths, stories, art, and architectural metaphors.

Mythology

Arachne, the Lydian weaver in Ovid's Metamorphoses, challenged Athena to a weaving contest, won, and was transformed by the furious goddess into the first spider — fated to weave forever. The whole order Araneae takes its name from her.

In West African and Caribbean folklore, Anansi is the spider trickster — clever, vain, often greedy, but always coming out on top through wits. The Cherokee tell of Grandmother Spider bringing fire to the world in a tiny clay pot on her back.

The famous tale of Robert the Bruce sheltering in a cave and watching a spider try, fail, and finally succeed in spinning a thread between two beams — and resolving to try again himself — appears to be a 19th-century invention by Sir Walter Scott. Webster's grandmother is, sadly, only legendary.

Literature

Charlotte the Tiderwider in E. B. White's Charlotte's Web (1952) did more for the spider's reputation than any field guide. Tolkien's Shelob and Ungoliant pulled the other direction. Anansi has spawned a literature of his own, including Neil Gaiman's Anansi Boys.

Web as metaphor

Almost every modern technology metaphor — the World Wide Web, social networks, the web of significance — borrows the spider's architectural vocabulary. We are, in a real sense, living inside a metaphor she invented 200 million years before us.

17Myths & misconceptions

"You swallow eight spiders a year while you sleep"

An invention. The figure originated in a 1993 magazine column as an example of bogus statistics that get repeated; ironically, it then got repeated. Spiders avoid sleeping mammals because we breathe, snore, and rumble — all signals of a large, dangerous, non-prey item. The number is essentially zero.

"There's always a spider within three feet of you"

This one might actually be true outdoors in temperate grasslands, given the density of money spiders. Indoors it's overstated, and depends a lot on the room and the season.

"Daddy long-legs are the most venomous spiders but their fangs are too small to bite humans"

Comprehensively false. Pholcus phalangioides can bite humans (the bite is a brief sting, no worse than a nettle), and its venom is unremarkable. The myth started on a US TV show in the early 2000s. Actual experiments have shown the bite is barely detectable.

"All spiders bite"

Most British spiders' fangs cannot penetrate human skin at all. Of those that can, most won't try unless squeezed against the skin (a hand inside a glove, an arm rolled onto in bed). Bites are genuinely rare events.

"Spider plants attract spiders"

They don't. The chlorophytum was named for its spidery shape, not any arachnid affinity.

"You can identify a black widow by the red hourglass"

Only on the underside of mature females, only in some species, and there are several other UK spiders (woodlouse spider, false widow) with red or orange marks that get misidentified.

18Conservation

The British spider fauna is generally robust, but several specialist species are endangered, almost always because of habitat loss.

The fen raft spider

Dolomedes plantarius is the largest spider in Britain and one of the rarest — historically found at only three sites (Redgrave & Lopham Fen in Suffolk, Pevensey Levels in Sussex, and the Crymlyn Bog in Wales). A long-running reintroduction programme has now established new populations in the Norfolk Broads, raising hopes for the species. Adults float on pond surfaces hunting insects and small fish.

The ladybird spider

Eresus sandaliatus was thought extinct in Britain until rediscovered on a Dorset heath in 1980. The males are vividly red and black like a ladybird, the females larger and matt black. Currently confined to one small site in Dorset, despite reintroduction attempts elsewhere.

What you can do

• Don't squash spiders. Use a glass and a card.
• Leave a "messy corner" in the garden — long grass, leaf litter, old logs.
• Let some windowsill webs persist, especially in autumn.
• Submit records to the British Arachnological Society's Spider Recording Scheme; citizen-science records have been important in tracking the spread of false widows and the recovery of fen raft spiders.
• Support heath, fen, and grassland conservation — the habitats where the rare specialists live.

19Identification tips

Identifying a spider from a photo is roughly the job of this app, but knowing what to look at helps. The most important features:

1. Body shape and proportions

Is the abdomen rounder than the cephalothorax, or longer? Is the abdomen pointed, segmented, or smooth and bulbous? The ratio of body parts narrows down the family quickly.

2. Eye arrangement

If you can see the face, the eye pattern is diagnostic at family level. Two large forward eyes = jumping spider. Two large rear eyes plus four below = wolf spider. A circle of six eyes = woodlouse spider. Etc.

3. Leg length and posture

Legs much longer than body, slender, dangling = cellar spider. Front two legs much longer than the rest, held forward = crab spider. All legs roughly equal, body close to the ground = wolf or jumping spider.

4. Markings on the abdomen

Cross of white dots = garden spider. Single skull-shape = noble false widow. Folium (oak-leaf-like) pattern = many orb-weavers. Plain glossy black or brown with no pattern = several house and ground spiders.

5. Web type, if present

Tidy 2D wheel = orb-weaver. Flat sheet with knockdown threads = sheet-web spider (money spider). Funnel into a tube = funnel-web spider. Three-dimensional tangle = cobweb spider (Theridiidae).

6. Behaviour and pose

A spider with two pairs of front legs held out wide is probably a crab or huntsman. A spider holding its abdomen above the head and rocking is probably a long-jawed orb-weaver. A spider hanging upside down in the centre of its web in good light is almost certainly a garden spider.

7. Where you found it

The single most useful fact, often. Bath = Tegenaria/Eratigena. Window frame = Zygiella. Sunny brick wall = Salticus. Long grass = Pisaura/Pardosa. A pond = Argyroneta or Dolomedes.

20Glossary

Araneae

The order containing all spiders.

Arachnida

The class containing spiders, scorpions, mites, ticks, and harvestmen.

Cephalothorax

The fused head-and-thorax front body part of a spider. Also called the prosoma.

Abdomen

The rear body part. Also called the opisthosoma.

Pedicel

The narrow waist joining the two body parts.

Chelicerae

The pair of biting appendages, each tipped with a fang.

Pedipalps

The pair of small leg-like appendages flanking the chelicerae. Sensory; in mature males, also reproductive.

Spinnerets

The silk-extruding organs at the rear of the abdomen.

Dragline

The silk thread a walking spider trails behind it as a lifeline.

Trichobothria

Long, fine sensory hairs that detect air movement.

Slit sensilla

Tiny pressure-sensing slits in the cuticle that detect substrate vibration.

Tapetum

A reflective layer behind the secondary eyes that improves night vision.

Synanthropic

An organism adapted to live alongside humans, usually in buildings.

Ballooning

Wind-borne dispersal using silk threads.

Stridulation

Rubbing of body parts to make sound; a few spiders do it. Crickets do it more.

Folium

The leaf-shaped pattern on the abdomen of many orb-weavers.

Epigyne

The female reproductive structure on the underside of the abdomen; species-specific in shape.

Cribellum

A specialised silk-spinning plate possessed by some spider families that produces "wool" silk.

Calamistrum

A comb on the rear leg used by cribellate spiders to comb out the wool silk.

Sclerotised

Hardened cuticle, as in fangs and leg tips.

21Citizen science & research

British arachnology depends heavily on amateur recorders. Most distribution maps in modern guides — including the spread of the noble false widow, the recovery of the fen raft spider, and the seasonal patterns of every common species — are built from records submitted by gardeners, naturalists, and walkers, not full-time scientists. Your sightings, properly logged, can contribute to this.

What a useful record contains

A sighting becomes a record when it has the elements that let another researcher verify, locate, and contextualise it. The standard biodiversity-data format is called Darwin Core, and it asks for:

• Scientific name — to species level if confidence allows, otherwise to genus or family with a confidence note.
• Date observed — the actual date you saw the spider, not just when you logged it.
• Location — a name (place / habitat) and coordinates if possible. Coordinates without a placename are fine; placenames without coordinates are weaker but still usable.
• Recorder — who you are, so others can follow up if needed.
• Habitat — what kind of place was it (garden wall, leaf litter, pondside, indoors).
• Sex and life stage if you can tell — adult female and adult male spiders of many species look quite different and the data is more useful split out.
• Body length in millimetres — a rough measurement from the tip of the abdomen to the front of the head, not including legs.
• Count — was it a single specimen, or several?
• A photograph — the gold standard for verification. Top-down view if possible, on a plain background.

The sightings log in this app captures all of these. The CSV export uses Darwin Core column names so it can be uploaded to most biodiversity databases without reformatting.

Where to submit records

• British Arachnological Society — Spider Recording Scheme. The authoritative UK database. Submissions are reviewed by experts; verified records appear in distribution maps and the next national atlas. srs.britishspiders.org.uk
• iRecord. The UK Biological Records Centre's general-purpose tool, used across taxonomic groups. Records are forwarded to the relevant scheme. irecord.org.uk
• iNaturalist. International, photo-led, with a built-in identification community. UK records flow to the national database via an iNaturalist–iRecord integration. inaturalist.org
• GBIF (Global Biodiversity Information Facility). The worldwide aggregator; UK records reach it via NBN Atlas. gbif.org

Practical field tips

• Photograph from above and from the side, both. Eye arrangement, abdomen pattern, and leg proportions all matter.
• Include a scale if you have one — a 5p coin (18 mm), a ruler, a fingernail. Photos with no scale are nearly worthless for size verification.
• Don't kill voucher specimens casually. Most amateur records don't need a specimen; a good photo is better and lighter on conscience.
• Note the weather and time of day — phenology matters and these data are often missing.
• Geolocate at the spider, not from the car park later. Modern phones are accurate to within 10 metres; that level of precision matters for site-specific specialists like the ladybird spider.
• If you're uncertain, log it as the genus or family rather than guessing the species. "Theridiidae sp." is far more useful than "noble false widow (probably)" if you weren't sure.

22Quick questions

23Sources & further reading

1. British Arachnological Society. The authoritative UK body for spider research, recording, and identification. britishspiders.org.uk
2. Spider Recording Scheme. Citizen-science database run by the BAS, with distribution maps for every British species. srs.britishspiders.org.uk
3. Bee, L., Oxford, G. & Smith, H. (2017). Britain's Spiders: A Field Guide. Princeton University Press / WildGuides. The definitive modern field guide; photographs and identification keys for every species.
4. Roberts, M. J. (1995). Spiders of Britain and Northern Europe. Collins Field Guide. Older but unmatched for illustration quality.
5. Foelix, R. (2010). Biology of Spiders (3rd ed.). Oxford University Press. The standard scientific text on spider biology.
6. The World Spider Catalog. Continuously updated taxonomic database of all known species. wsc.nmbe.ch
7. Wikipedia: Spider. Comprehensive overview of biology, behaviour, and culture. en.wikipedia.org/wiki/Spider
8. The Society of Biology / Royal Entomological Society. Both publish accessible articles on spider biology and conservation.
9. Nyffeler, M. & Birkhofer, K. (2017). "An estimated 400–800 million tons of prey are annually killed by the global spider community." The Science of Nature 104:30. The source of the world-spider-biomass figure cited in chapter 9.
10. Mason, L. D., Wardell-Johnson, G. W., & Main, B. Y. (2018). "The longest-lived spider: mygalomorphs dig deep, and persevere." Pacific Conservation Biology. Reports the death of the 43-year-old trapdoor spider.