Identification
Physical Characteristics
Size: The body length of a mature female can be up to 40mm (4 cm). Males are slightly smaller, with a body length of around 30mm (3 cm).
Coloration: The spider has a uniform reddish-brown to dark-brown colouration over its entire body and legs. It lacks any distinctive patterns, stripes, or markings. The abdomen is slightly lighter brown and covered in fine, greyish hairs. This simple colour scheme is typical for a creature that lives in complete or near-complete darkness.
Key Features: Its giant size, with a leg span often exceeding 15cm, is its primary feature. It is the largest known araneomorph spider in terms of leg span. Its restriction to Tasmanian caves and forests, its primitive jaw structure, and the large, sheet-like webs it builds are also key identifiers.
Biology & Lifecycle
Development & Reproduction
Reproduction Rate: Reproduction is a very infrequent event. A female may only produce one or two egg sacs in her entire multi-decade lifetime.
Lifecycle Details
Egg Stage
After a successful and precarious mating, the female constructs a very large and distinctive egg sac. The sac is pear-shaped or teardrop-shaped, about 4-5 cm long, and made of brilliant white, papery silk. She hangs this sac from the cave ceiling with a strong silk stalk. The sac is sealed with a thick, glue-like substance that makes it waterproof and protects the eggs from fungus and predators. Each sac contains around 40-50 eggs. The female guards the sac until she dies.
Larval Stage
The eggs develop very slowly in the constantly cold cave environment. After hatching, the spiderlings (no larval stage) remain inside the highly protected egg sac for an extended period, possibly up to a year. They live off their yolk reserves and will go through their first moult inside the sac.
Pupal Stage
There is no pupal stage. Once the spiderlings emerge from the egg sac, they are on their own. They disperse into the surrounding darkness of the cave. They will begin to construct their own small sheet webs to catch any tiny invertebrates that are available.
Adult Stage
The Tasmanian Cave Spider has an exceptionally long lifespan, a trait common in stable, cold environments with low metabolic rates. It is estimated that they can live for several decades, possibly up to 30 years or more. They take many years to reach sexual maturity. This slow-paced life is perfectly adapted to the unchanging world of a cave.
Reproduction Rate
Reproduction is a very infrequent event. A female may only produce one or two egg sacs in her entire multi-decade lifetime.
Generations Per Year
Generations are not measured on an annual basis. A generation time could be a decade or more.
Development Time
The time from egg to sexual maturity is extremely long, likely taking 5-10 years or even longer.
Seasonal Cycle
Living in the eternal stability of caves, this spider has little to no seasonal cycle. Mating and other life events are not tied to the seasons of the outside world. It is active year-round within its dark domain.
Environmental Factors
The key factors are a permanent, stable environment with very high humidity (near 100%), constant darkness, and a stable low temperature. It is entirely dependent on the unique and fragile cave ecosystem.
Habitat & Distribution
Preferred Habitats
- Deep, dark, and wet limestone or dolerite caves in Tasmania.
- Sinkholes and deep, shaded, permanently wet forest gullies.
- Hollow logs and underground drainage systems in wet forests.
- Any environment that mimics a cave: constant darkness, stable low temperature, and near 100% humidity.
- They are a 'troglophile'—a species that lives in and is adapted to the cave environment.
Distribution Patterns
Australian Distribution
- Tasmania
Climate Zones
- Temperate
Urban vs Rural Distribution
Exclusively found in wild, natural environments. It cannot survive in urban or rural settings. It is found only in specific cave systems and deep, undisturbed wet forests.
Native Range
Endemic to Tasmania. It is found nowhere else in the world.
Introduced Range
Not introduced anywhere.
Introduction History
A native, relict species from the Gondwanan supercontinent.
Current Spread
No spread is occurring. The range is static and defined by the location of suitable caves. The main concern is range contraction due to habitat disturbance.
Limiting Factors
Its distribution is strictly limited by the availability of suitable cave habitats with high humidity and stable, low temperatures. It is highly vulnerable to changes in its environment.
Behavior & Diet
Activity Pattern
As a creature of constant darkness, it does not have a day/night activity cycle. It is perpetually active, waiting for prey in its web.
Dietary Preferences
Feeding Habits
It is a generalist predator of any invertebrate of a suitable size that lives in or wanders into the cave environment.
Health Risks
Always consult healthcare professionals for medical concerns related to pest exposure.
Disease Transmission
- None. Poses absolutely no health risk to humans.
Allergens and Respiratory Issues
None known.
Contamination Risk
None. It lives in environments far from human food sources.
Vulnerable Populations
- Not applicable. The spider is vulnerable to humans, not the other way around.
Symptoms of Exposure
- A bite has never been recorded. Even if it were to bite in defence, its venom is not considered dangerous to humans. It is an extremely timid creature.
- No adverse symptoms would be expected.
Transmission Methods
- A defensive bite is the only theoretical possibility, but it is extremely unlikely to ever happen.
Risk Severity
Low (Harmless). This spider is not medically significant.
Economic Impact
Treatment Costs
Professional Treatment
Not applicable.
Prevention Costs
Not applicable.
Diy Treatment
Not applicable.
Property Damage
Structural Damage
None.
Garden Damage
None.
Food Contamination
None.
Equipment Damage
None.
Business Impact
Restaurant Issues
None.
Retail Impact
None.
Reputation Damage
Its presence can be a significant positive for ecotourism businesses that run cave tours. It is an attraction, not a detriment.
Operational Disruption
None.
Agricultural Impact
Crop Damage
None.
Yield Loss
None.
Beneficial Aspects
Its primary value is scientific and ecological. As a top predator in the cave ecosystem, it is a keystone species, vital for the health of that unique environment. It is also a significant draw for cave-based ecotourism.
Economic Loss
None.
Indirect Costs
Healthcare Costs
Zero.
Cleanup Costs
The cost of cave restoration or protection if its habitat is damaged is the only, and significant, indirect cost.
Replacement Costs
Zero.
Preventive Maintenance
Costs associated with protecting its cave habitats from land clearing, pollution, and climate change.
Detection & Signs
Visual Signs
- 'Infestation' is not an appropriate term. Signs of its PRESENCE include:
- The large, conspicuous, horizontal sheet webs, which can cover large areas of a cave ceiling.
- Spotting the spider itself, hanging upside down beneath its web.
- Finding the large, white, pear-shaped egg sacs suspended from the ceiling.
Physical Evidence
- The webs and egg sacs are the primary physical evidence.
- Shed exoskeletons (moults) may be found within the web.
- The remains of prey, like cricket legs or beetle elytra, might be found on the cave floor below a web.
Behavioral Signs
- The spider retreating rapidly across its web when illuminated by a torch.
- This is the only behavioural sign most people will ever see.
Seasonal Indicators
- There are no seasonal indicators, as the cave environment is stable year-round.
Early Warning Signals
- Not applicable. Its presence is a sign of a healthy, ancient ecosystem, not a problem to be warned of.
Prevention
Sanitation Measures
- Not applicable. The goal is to preserve its environment, not prevent the spider.
Exclusion Methods
- Not applicable. Exclusion from its natural habitat would be a conservation disaster.
Landscaping Tips
- The only relevant 'landscaping' is the conservation of Tasmanian old-growth wet forests and the protection of cave systems from damage, pollution, and hydrological changes.
Monitoring Strategies
- Monitoring is conducted by scientists and conservation groups to track population health.
- This involves surveying caves, counting webs, and assessing the impacts of tourism or external environmental changes.
- Cavers are encouraged to report sightings and population estimates to relevant authorities.
Environmental Modification
- All environmental modification of its habitat should be avoided. This includes changing airflow, water flow, or temperature within a cave, all of which can be catastrophic for the spiders.
Control Methods
Professional Treatment Methods
Chemical Control
Never. It is illegal and ecologically reprehensible to use chemicals against this species.
Biological Control
Not applicable.
Physical Control
Not applicable.
Integrated Approach
The only integrated approach is for its CONSERVATION. This involves habitat protection, minimising human impact during cave tours (e.g., sticking to marked paths, using appropriate lighting), and public education.
DIY Treatment Options
Natural Remedies
Not applicable.
Home Made Traps
Not applicable.
Deterrent Methods
Not applicable.
Mechanical Control
Not applicable.
Treatment Effectiveness
Success Rate
Not applicable.
Timeframe
Not applicable.
Follow Up Required
Not applicable.
Seasonal Considerations
Not applicable.
Application Techniques
- Not applicable.
Professional Services
Professional Treatment Services
Chemical Control
Never. It is illegal and ecologically reprehensible to use chemicals against this species.
Biological Control
Not applicable.
Physical Control
Not applicable.
Integrated Approach
The only integrated approach is for its CONSERVATION. This involves habitat protection, minimising human impact during cave tours (e.g., sticking to marked paths, using appropriate lighting), and public education.
Professional Treatment Costs
Not applicable.
Treatment Success Rates
Not applicable.
Treatment Timeframe
Not applicable.
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Browse All ProvidersSeasonal Patterns
Spring Activity
No distinct seasonal activity. Life continues at its slow pace.
Summer Activity
No distinct seasonal activity.
Autumn Activity
No distinct seasonal activity.
Winter Activity
No distinct seasonal activity.
Breeding Season
Breeding is not tied to a specific season.
Peak Activity Period
Not a pest. Always present in its habitat.
Environmental Factors
Temperature Effects
Requires constant, low temperatures. Any significant fluctuation is a threat.
Humidity Effects
Requires constant, near-100% humidity. Drying of the cave environment would be fatal.
Photoperiod Effects
None, as it lives in perpetual darkness.
Weather Patterns
It is buffered from external weather. However, major droughts could lower the water table and affect cave humidity, while floods could destroy webs and drown spiders.
Legal Considerations
Pest Status
It has no pest status. It is a protected native species.
Control Regulations
Control is illegal. All regulations are aimed at its protection under Tasmania's wildlife and conservation laws.
Professional Requirements
Permits from Tasmania's Department of Natural Resources and Environment are required for any scientific study or interaction with this species.
Environmental Considerations
The species is a flagship for cave ecosystem conservation. Protecting the spider means protecting the entire fragile cave environment from pollution, physical damage, and changes to hydrology.
Compliance Requirements
- Strict adherence to Tasmanian and Australian wildlife protection laws.
- Cavers must follow minimal impact caving codes.
- Tourist operators must have management plans to minimise disturbance.
- Permits are required for research.
Frequently Asked Questions
Is the Tasmanian Cave Spider the biggest spider in Australia?
This depends on how you measure 'biggest'. In terms of sheer leg span, the Tasmanian Cave Spider is a contender for the largest in Australia, with its legs stretching up to 18 cm. However, when measured by body mass and bulk, the title of 'biggest' usually goes to the Australian Tarantulas, also known as 'Whistling Spiders' (genus *Selenocosmia*), found on the mainland. These tarantulas are much heavier and more robustly built, even if their leg span might be slightly less than a particularly large *Hickmania*. So, it's fair to say the Tasmanian Cave Spider is Australia's 'leggiest' giant, while the tarantulas are the 'heaviest'.
Why does this spider only live in Tasmanian caves?
*Hickmania troglodytes* is a living relic, the last known survivor of a family of spiders that existed on the ancient supercontinent of Gondwana. When Australia separated and drifted north, the climate became much warmer and drier. This spider, adapted for cool, damp, stable conditions, could not survive the changes on the mainland. Tasmania, however, remained cooler and wetter, and its extensive cave systems provided the perfect, unchanging refuge. These caves act as natural time capsules, preserving the exact conditions—constant low temperature, 100% humidity, and total darkness—that the spider needs to live. It is so specialised that it cannot survive outside of these specific habitats. Its distribution is a map of where these ancient Gondwanan conditions still persist.
I'm going caving in Tasmania. Am I likely to see one and is it dangerous?
If you are exploring one of the known habitats for this spider, then yes, you have a good chance of seeing one, or at least its large sheet web. They are a highlight for many cavers. However, you have absolutely nothing to fear. The Tasmanian Cave Spider is considered completely harmless to humans. It is an extremely timid creature whose only instinct when confronted with the light and vibration of a human is to retreat rapidly. Its venom is not medically significant, and its fangs are designed for tackling cave crickets, not people. To be bitten, you would have to capture one and severely provoke it, which is not only difficult but also illegal, as they are a protected species. When caving, follow your guide, stick to paths, and admire these magnificent creatures from a respectful distance.
What does it mean that it's a 'primitive' spider?
Calling it 'primitive' refers to the fact that it retains several anatomical features that were common in ancient spiders but have been lost or modified in most 'modern' spiders. It's like looking at a living fossil. One key feature is its fang structure (chelicerae), which is in an intermediate state between the ancient mygalomorphs (like tarantulas) and the modern araneomorphs (like orb-weavers). Another primitive trait is its respiratory system; it has two pairs of 'book lungs', which are simple, layered respiratory organs. Most modern spiders have modified this system, having only one pair of book lungs or replacing them with more efficient tubes called tracheae. Studying *Hickmania* gives scientists a precious glimpse into the evolutionary history of all spiders.
What are the main threats to the Tasmanian Cave Spider?
The main threats to this species are all related to the destruction or alteration of its incredibly specific and fragile habitat. Because it is so highly adapted to stable conditions, any change can be catastrophic. The primary threats include: deforestation of forests above the caves, which can alter water seepage and humidity levels; pollution of groundwater that flows into the caves; and direct human disturbance. This includes unregulated cave tourism, quarrying activities that can collapse cave systems, and anything that alters the temperature or airflow within a cave. Climate change also poses a long-term threat, as a significant increase in Tasmania's average temperature or changes in rainfall patterns could render these ancient refuges uninhabitable. Conservation efforts are therefore focused on protecting the entire cave catchment area, not just the cave entrance.
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Image Gallery
Images of Tasmanian Cave Spider showing key identifying features: