Short answer: The spiders usually called “cave spiders”, such as the European cave spider (Meta menardi) and the Tasmanian cave spider (Hickmania troglodytes), are not regarded as medically significant. Like nearly all spiders they have venom, but they are shy predators of small invertebrates and are not listed among the spiders that health agencies treat as a medical concern.
The one real caveat is regional. “Cave spider” is not a single species, and in the Americas some recluse spiders (Loxosceles), a genus that includes medically important species, also live in caves. If you are bitten and symptoms are severe or getting worse, get medical advice rather than guessing which spider was involved.
“Cave spider” means different spiders in different places
There is no one animal called the cave spider. The name gets attached to whichever large spider people notice near cave entrances in their part of the world. In Britain and Europe that is usually Meta menardi. In Tasmania it is Hickmania troglodytes. In northern New South Wales, the Carrai cave spider (Progradungula carraiensis) is the best-known example.
Scientists also use a few more precise terms. A troglobiont is an animal that lives only underground and often shows cave adaptations such as reduced eyes and pale colouring. A troglophile can complete its life cycle in caves but also lives in similar dark, damp places outside them. Most of the spiders people meet at cave entrances are troglophiles.
Cave life has evolved many times. A 2017 review by Stefano Mammola and Marco Isaia found cave-dwelling species scattered across many unrelated spider families, from primitive segmented spiders to wolf spiders. The first eyeless cave spider to be scientifically described was Stalita taenaria, named by Jørgen Schiødte in 1847 from caves in what is now Slovenia; it is still an accepted species in the family Dysderidae.
Cave spiders you are most likely to hear about
The table below covers the spiders most often meant by “cave spider” in English-speaking countries, plus the one group where caution is genuinely warranted.
| Common name | Scientific name & family | Where | Size | Medical significance |
|---|---|---|---|---|
| European cave spider | Meta menardi, Tetragnathidae | Europe, plus records from North Africa, Turkey and Iran | Body about 11–12 mm (male), 15–17 mm (female) | Not considered medically significant |
| North American cave spider | Meta ovalis, Tetragnathidae | USA and Canada | Not verified here | Not considered medically significant |
| Tasmanian cave spider | Hickmania troglodytes, Gradungulidae | Tasmania only | Body 13–20 mm; leg span up to about 18 cm | Not listed as medically significant in Australia |
| Carrai cave spider | Progradungula carraiensis, Gradungulidae | Carrai Plateau, northern New South Wales | 8–12 mm | Not listed as medically significant in Australia |
| Recluse spiders (cave-dwelling species) | Loxosceles spp., Sicariidae | Parts of the Americas, including caves in Brazil | Varies by species | The genus includes medically important species; treat with caution |
European cave spider (Meta menardi)
This is the spider most British and European cavers mean. It is a member of the long-jawed orb-weaver family, Tetragnathidae, with a glossy, rounded abdomen and long legs. It lives in the dim zone just inside caves and mines, and the British Arachnological Society’s recording scheme also has records from cellars, culverts, ice-houses and drain covers. Females hang distinctive white, teardrop-shaped egg sacs from the ceiling.
Despite its size, it spends most of its time motionless on the cave wall, feeding on small invertebrates that move through the entrance zone. Recording-scheme notes on the species focus on its habitat and egg sacs, not on any risk to people.
Tasmanian cave spider (Hickmania troglodytes)
Tasmania’s cave spider is a big spider, with a leg span that can reach about 18 cm and a body of 13–20 mm. It is widespread in Tasmania wherever there are caves or underground drainage, and it also uses hollow logs, the undersides of bridges and other cool, dark spots. It hangs beneath a broad sheet web that can be more than a metre wide.
The species belongs to an ancient lineage. The World Spider Catalog currently places it in the family Gradungulidae, alongside the Carrai cave spider, although some older references still list it under Austrochilidae. The Australian Museum notes a slow life history: spiderlings take eight to ten months to emerge from the egg sac, and individuals can be long-lived.
Its size makes it look intimidating, but it is not one of the spiders Australian poison authorities treat as harmful. The NSW Poisons Information Centre names funnel-web and redback spiders as the Australian species that can harm people.
Carrai cave spider (Progradungula carraiensis)
This small spider, 8–12 mm long, is known from limestone caves and moist forest on the Carrai Plateau in northern New South Wales, and it probably also lives on rocks and tree trunks outside the caves. Inside caves, the Australian Museum notes that webs are usually placed near entrances or where bat guano collects, areas with more insect prey.
Its hunting method is unusual. It builds a small, ladder-like platform of woolly cribellate silk, about 25 by 6 mm, suspended just above the ground by a network of threads. The spider hangs head-down on this platform with its long, hooked front legs just above the floor. When an insect walks underneath, it lunges, scoops the prey up onto the sticky silk and bites it. Beetles, flies, moths and crickets have been recorded as prey.
Its unusual web has made it a useful species in research on how web-building evolved in spiders. Two related species are now recognised: Progradungula otwayensis from Victoria and P. barringtonensis, described from New South Wales in 2024.
Recluse spiders in caves
Recluse spiders (Loxosceles) are the reason “cave spiders are harmless” should not be stated as a universal rule. Several recluse species live in caves in Brazil, most of them troglophiles that also occur outside caves, and the genus includes species whose bites can cause serious skin damage. In the United States, the CDC notes that the brown recluse favours dry, sheltered, undisturbed places in the Midwest and South.
That does not mean a spider in a cave is likely to be a recluse. It means location matters: a large orb-weaver-type spider near a British cave entrance is a very different situation from a recluse-type spider in a dry cave in the southern United States or Brazil.
Venomous, not poisonous
People often ask whether cave spiders are poisonous, but that is the wrong word. A poisonous animal harms you if you eat or touch it. A venomous animal injects venom, and spiders do this through their fangs.
Almost all spiders are venomous, because venom is how they subdue prey. Having venom says very little about risk to humans, though. What matters is whether a spider’s fangs can easily pierce human skin, how much venom it delivers, and whether that venom affects mammals. Only a small number of spider species worldwide cause serious bites, and the cave spiders described above are not among them.
Thinking of the game? In Minecraft, the cave spider is a hostile mob that can poison the player. That is a game mechanic, not biology, and real cave spiders do not behave that way.
Could a cave spider bite you?
Any spider with fangs strong enough to break skin could bite if it is grabbed, pressed against the body or trapped in clothing. Cave spiders spend most of their time still, in places people rarely touch, so bites are unlikely during a normal cave visit. If one did bite, the most likely outcome for the non-medically-significant species above would be a local reaction such as pain, redness or swelling.
Two points matter more than any symptom list:
- A skin mark does not prove a spider bite. Many skin infections and other conditions are mistaken for spider bites, and symptoms alone cannot tell you which spider, if any, was involved.
- Do not catch or handle an unknown spider to identify it. A photo taken from a safe distance is more useful and avoids a second bite.
What to do after a suspected spider bite
For a mild local reaction, general first-aid advice from public-health agencies includes washing the area with soap and water, applying a cold compress wrapped in cloth, raising the area if you can, and avoiding scratching. Watch for signs of infection, such as increasing redness, heat, swelling or pus.
Get urgent help for any sign of a serious allergic reaction (swelling of the lips or throat, difficulty breathing, fainting), severe or spreading pain, sweating, vomiting, muscle twitching, or symptoms that are getting worse. Advice depends on where you are:
- Australia: call 000 in an emergency. For a suspected funnel-web bite, keep the person still and apply a pressure bandage while waiting for help. For other spider bites, the Poisons Information Centre is on 13 11 26.
- United States: call 911 in an emergency, or Poison Help on 1-800-222-1222 (free, 24 hours).
- United Kingdom: call 999 in an emergency, or NHS 111 for urgent advice.
- Elsewhere: use your local emergency number or national poison centre.
For more on how to judge bite risk in general, see the Spider Bite & Danger section.
Visiting caves safely around spiders
- Look before you put your hands on ledges, in crevices or under rocks, especially near cave entrances where spiders are most common.
- Wear gloves when moving rocks or debris, particularly in regions where recluse or widow spiders occur.
- Shake out boots, gloves and clothing left on the ground before putting them back on.
- Leave webs and egg sacs alone. Some cave spiders are slow-breeding, range-restricted species, and disturbance can matter more to them than to you.
Cave spiders are part of a fragile underground food web, and several are known only from a few sites. If you are trying to work out which spider you found, start with location and a combination of features rather than colour alone; our spider identification guide walks through the clues that help most. You can also read more about where spiders live in the Spider Habitat section, or why predators like these matter in why spiders are important.
References
- World Spider Catalog (2026). Version 2026. Natural History Museum Bern. Entries for Hickmania troglodytes, Stalita taenaria, Meta ovalis and Progradungula barringtonensis. wsc.nmbe.ch
- Nentwig, W., Blick, T., Bosmans, R., Gloor, D., Hänggi, A. & Kropf, C. Spiders of Europe: Meta menardi. araneae.nmbe.ch/data/755
- British Arachnological Society, Spider and Harvestman Recording Scheme. Notes on Meta menardi. srs.britishspiders.org.uk
- Australian Museum. Carrai Cave Spider. australian.museum
- Australian Museum. Tasmanian Cave Spider. australian.museum
- Mammola, S. & Isaia, M. (2017). Spiders in caves. Proceedings of the Royal Society B 284: 20170193. doi.org/10.1098/rspb.2017.0193
- Bertani, R., von Schimonsky, D. M., Gallão, J. E. & Bichuette, M. E. (2018). Four new troglophilic species of Loxosceles Heinecken & Lowe, 1832: contributions to the knowledge of recluse spiders from Brazilian caves. ZooKeys 806. doi.org/10.3897/zookeys.806.27404
- NSW Poisons Information Centre. Spiders. poisonsinfo.nsw.gov.au
- Centers for Disease Control and Prevention (NIOSH). Venomous Spiders. cdc.gov
- NHS. Insect bites and stings. nhs.uk
- Health Resources and Services Administration. Poison Help line. poisonhelp.hrsa.gov
