Tasmanian Cave Spider Identification in Australia

About the Tasmanian cave spider

Tasmanian cave spiders are distinctive large spiders confined to Tasmania. They are most strongly associated with caves, but can also be found in cool, damp, dark places such as hollows, old tunnels, mine workings and sheltered natural retreats. Their size can be unnerving, yet they are not usually considered aggressive or dangerous to people.

Exact-species hero photograph: Hickmania troglodytes by Marshal Hedin, CC BY-SA 2.0 via Wikimedia Commons.

How to identify the Tasmanian cave spider

The accepted species on this page is Hickmania troglodytes (Higgins & Petterd, 1883), a cribellate araneomorph currently placed in the family Gradungulidae by the World Spider Catalog. Older museum and field references may place it in Austrochilidae or use the earlier names Theridion troglodytes and Ectatosticta troglodytes; those historical labels do not indicate separate Tasmanian species. The most useful field combination is a large, very long-legged spider associated with a broad suspended sheet of woolly cribellate silk in Tasmania. Australian Museum measurements give a body length of about 13–20 mm and a leg span up to 180 mm, so the spider can create a hand-span impression even though the body is much shorter. The body is usually brown, grey or subdued patterned rather than brightly marked. A cave entrance, hollow log, bridge underside, old tunnel or other cool dark retreat strengthens the identification, but a location alone is not proof. The web is a broad, simple sheet that may exceed a metre across; it is not a neat orb and should not be treated as a typical funnel-web burrow. Photographs should show the whole web, support surface and spider in context. A specialist specimen or genital examination remains more reliable than a casual photograph, especially when the web is damaged or only the long legs are visible.

Clues that are not enough on their own

• A hand-span or coin comparison without a measured body and leg scale
• Any long-legged brown spider in a cave, cellar or shed
• A sheet, funnel or dusty web without seeing the spider and its supports
• Tasmania as the only clue when the locality and habitat are unrecorded
• A pale underside or four light patches inferred from a distant photograph
• A web that is wider than a metre treated as mandatory for every individual
• A cave entrance assumed to contain Hickmania rather than another cave invertebrate
• An old Theridion, Ectatosticta, Austrochilidae or “ancient spider” label treated as a current identification
• A related long-legged spider photographed on the mainland assigned to this species

Colour, sex and life-stage variation

Body colour and contrast vary with age, sex, moult, cave light, wet silk and camera exposure. Females are generally larger and heavier-bodied; adult males may look slimmer and can be encountered away from the centre of a web while searching for a mate. Juveniles build smaller sheets and may be much harder to recognise. A web can be sparse, dusty, torn or partly hidden by rock, wood, a bridge beam or cave decoration, so the famous metre-wide sheet is not present at every observation. The long legs may be folded beneath the sheet or stretched across it, changing the apparent size. The four pale book-lung patches sometimes described on the underside are not a safe feature to inspect in the field because handling is unnecessary and the view is often unavailable. Do not turn a brown colour, a hand-span estimate, a cave name or a single long-legged silhouette into a species call without the web, Tasmania-only range and body context agreeing.

Behaviour, web and retreat

Hickmania is a web-associated predator. It hangs beneath or alongside the sheet and waits for cave crickets, beetles, flies, spiders, millipedes and other arthropods to fall, jump or walk into the dense woolly silk. The cribellate fibres are not a sticky orb-web spiral; the tangled surface intercepts prey and gives the spider traction while it runs over the sheet. Webs may span cave mouths or walls, but the species also uses hollow logs, gaps between boulders, bridge recesses, cellars and other sheltered structures outside caves. The spider can retreat when a torch beam, vibration, rain or a person reaches the silk, so an empty web does not prove that it has left. Courtship is unusually prolonged: the male plucks the female’s web and taps or beats with his legs before mating, and research records a specialised kink on the second leg used to restrain the female safely. Females guard unusual pear-shaped egg sacs; young may remain inside for eight to ten months before emerging. Do not lift bark, probe a cave wall or place a hand under a sheet to make the spider move.

Australian distribution

The World Spider Catalog and Australian biodiversity records treat Hickmania troglodytes as a single accepted species confined to Tasmania. It is widely distributed across the island where suitable cool, moist and sheltered structures occur, including cave systems and cave entrances, but it is not a mainland Australian species. Mole Creek and other karst areas are well-known settings, yet a Tasmanian observation outside a show cave can still be plausible in a hollow tree, rock gap, tunnel, bridge recess or cellar. The species should not be widened to Victoria or New South Wales because a long-legged cave spider looks similar there, and the presence of a cave does not establish H. troglodytes unless the locality is Tasmania. Tasmanian cave fauna is sensitive to trampling, changed airflow, lighting and web damage, particularly around cave entrances where crickets and spiders concentrate. Keep the state filter narrow, preserve the exact locality and note whether the web was in the entrance, twilight zone or a dark sheltered structure. Museum or biodiversity review is appropriate when a photograph lacks the spider and web together.

What to do if you find one

Treat the web and its cave as protected habitat. Stay on marked paths, keep clear of cave walls and entrances, do not touch silk, and never collect the spider or egg sac. Photograph from the trail with the whole sheet, its supports and a distant scale reference already present in the scene; do not put a ruler, hand, phone or flash against the web. In a cellar, tunnel or bridge recess, use a torch without reaching into the retreat and leave the spider where it is. Wear closed shoes and gloves when moving firewood or stored materials, and keep children and pets away from unknown webs. This species is not usually regarded as medically important, but any suspected spider bite should be washed and observed. Seek medical advice for severe or spreading pain, allergic features, infection signs or uncertainty about the animal; call 13 11 26 for poisons advice and 000 for collapse or breathing difficulty. The site is an identification aid, not a substitute for an expert determination or medical diagnosis.

Compare with similar spiders

Use body shape, web or retreat, location and behaviour together before settling on a likely match.

• Black house spider — Sombrero spider / sheetweb spider - Stiphidion facetum makes a broad sheet with a raised central retreat and can share sheltered rock, bark or garden edges; its eastern Australian range and web architecture differ from Tasmania-only Hickmania.
• Curtain-web spider — Curtain-web spider - a large sloping sheet and dark retreat can suggest a curtain-web spider, but the spider, retreat and locality must agree; do not infer a funnel-web from a sheet alone.
• Sombrero spider — Black house spider - Badumna webs around buildings can be messy and lace-like, but the smaller body, wall setting and retreat structure usually differ from a giant cave-spider sheet.
• Huntsman spider — Huntsman spider - huntsman have long laterigrade legs and may enter caves or sheds, yet they do not build the suspended cribellate sheet; a long-legged silhouette without the web is not enough.

Sources for this profile

These accessible authoritative sources support the identification and bite-safety context on this page.

• World Spider Catalog: Hickmania troglodytes
• Australian Faunal Directory: Hickmania troglodytes
• Atlas of Living Australia: Hickmania troglodytes
• Australian Museum: Tasmanian cave spider
• Doran, Richardson & Swain 2001: reproductive behaviour
• Australian Museum: Prey capture and feeding
• Tasmania Parks and Wildlife Service: invertebrates
• Tasmanian Government: cave fauna management
• Australian Museum: Spider webs
• healthdirect: Spider bites

Profile review

Published by Spider Identifier Australia. Last factual review: 13 August 2026.