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Sources

Where the facts come from

Every factual claim on this site links to its source. This is the full list, and every place where the sources disagree.

How we checked

Each fact was written alongside its source. Our build script stores the source text and, for every fact, checks that the key words and figures really appear in it. 264 of 264 checks passed when this site was last built. All sources were read on 30 Oct 2026. Facts that can change (species counts, trends and records) carry “checked 30 Oct 2026” next to their source link.

Main sources: the Natural History Museum, London, the British Arachnological Society, The Wildlife Trusts, Manx Wildlife Trust, the Australian Museum, the Burke Museum, the World Spider Catalog, the University of Bristol, a peer-reviewed paper in PLoS ONE, the British Tarantula Society, the RSPCA, the Royal Veterinary College, legislation.gov.uk, Britannica (its main article text only) and Merriam-Webster.

When sources disagree

Where trusted sources give different figures, we don’t pick one: we show them all, each with its source.

How many kinds of spiders are there?

The World Spider Catalog is updated as new species are named; Britannica’s total is a rounder, older-looking figure. New species are still being described, so treat both as snapshots.

How many spider species does Britain have?

Four trusted sources, four figures. The 2025 checklist covers Great Britain and Ireland (and the Isle of Man); the others are rounded or older and cover slightly different areas. The sources don’t explain every gap.

How many spiders have been recorded on the Isle of Man?

The checklist figure is from 2019; Manx Wildlife Trust’s figure is more recent. Records are still being added, especially for tiny money spiders.

How many kinds of jumping spider are there?

Both sources agree jumping spiders are a huge family; they give different round figures.

How long do tarantulas live?

The two sources give different figures: a typical average from the British Tarantula Society and a range from the Royal Veterinary College. Lifespan varies with species and sex.

Do wolf spiders carry their young for days or weeks?

  • A female wolf spider carries her egg sac attached to her spinnerets, then carries the young on her back for a few days. The Wildlife Trusts: Wolf spider
  • Carrying the egg sac on the spinnerets is unique to wolf spiders. After hatching, the spiderlings ride on their mother’s back for several days to weeks. Britannica: Wolf spider

The Wildlife Trusts describes the common UK Pardosa amentata; Britannica covers the whole family, so its wider range is not a contradiction.

All sources (56)