Atrax robustus
Geographic Range
Found only in Australia within a 160-kilometer radius of Sydney. There are other species of funnel-web spiders in Eastern Australia, Victoria, South Australia and Tasmania.
(Atknison, 1981; Brown, 1999)
- Biogeographic Regions
- australian
Habitat
Sydney funnel-web spiders tend to live in lush gullies beneath rocks and fallen timber. They also live in moist soil beneath houses, crevices in garden rockeries and compost heaps. Their white silk webs are 20 to 60 cm long and go into ground that has stable, high humidity and low temperatures. The entrance is either y-shaped or t-shaped and is woven into a funnel, hence the name funnel-web spider.
(Mascord, 1980)
- Terrestrial Biomes
- forest
Physical Description
Sydney funnel-web spiders have large fangs and venom sacs. Males grow to 25mm long while females grow to 35 mm long. The color is a glossy blue-black and there are fine, velvety hairs covering the abdomen. Funnel-web spiders have shiny, solidly built limbs, a row of teeth along the fang groove and another row on their paired claws. Males are smaller, slimmer, and have longer legs.
(Brown, 1999; Hunter, 1982)
- Other Physical Features
- ectothermic
- bilateral symmetry
Reproduction
Male reproductive organs consists of testes and a tube that connects the testes to a small opening. Sperm is discharged onto a small silk mat that the spiders weave. Sperm is then discharged into the female's genital opening where it is either used or stored by the female. Reproduction usually occurs towards the end of summer or early fall. Males reach sexual maturity at about four years of age and the females take just a little bit longer. Females lay from 90 to 120 yellow-green eggs.
(Brown, 1999; Brunet, 1997)
- Key Reproductive Features
- gonochoric/gonochoristic/dioecious (sexes separate)
Behavior
Sydney funnel-web spiders are solitary animals except when mating. Females tend to stay in the same location except when forced out by flooding. Males tend to roam around in search of a mate after reaching sexual maturity. Males locate females by sensing the female's pheremones.
(Gray, 1988; Atkinson, 1981)
Food Habits
The diet of Sydney funnel-web spiders consists of beetles, cockroaches, insect larvae, native land snails, millipedes and occasionally frogs and other small vertebrates. All food is taken at the edge of their 'funnel-webs.' The webs are made entirely of dry silk. Insects often times land on the web; once they land, the trapped insects have trouble moving on the slippery web. Sydney funnel-web spiders have no trouble moving and repeatedly bite the trapped insect and takes it back into the funnel for feeding.
(Brunet, 1997)
Economic Importance for Humans: Positive
Silk made by Sydney funnel-web spiders is used as crosshairs in optical instruments.
(Overton, 1998)
Economic Importance for Humans: Negative
Sydney funnel-web spiders are very aggressive and will attack. They are known to have killed at least 15 people. A bite from this spider will not be fatal if treated immediately.
(Overton, 1998)
Conservation Status
The Australian Reptile Park has over 1000 funnel-web spiders where the venom is being extracted and tested to find a cure.
(Overton, 1998)
-
- IUCN Red List
- No special status
-
- US Federal List
- No special status
-
- CITES
- No special status
Other Comments
Sydney funnel-web spiders are probably the most deadly spider in the world; they do not hesitate to attack. They have fangs that can easily penetrate a human fingernail. Venom of Sydney funnel-web spiders has different affects on different animals; humans are highly affected by the venom.
(Atkinson, 1981)
Contributors
Jason Fathallah (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
Glossary
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
References
Atkinson, R. 1981. Naturally Occurring Inhibitors of the Venom of Funnel-web Spiders. Australian Journal, Vol. 22.
Brown, S. 2002. "Spider Envenomations, Funnel Web" (On-line). eMedicine. Accessed 10/27/04 at http://www.emedicine.com/emerg/topic548.htm.
Brunet, B. 1997. Spiderwatch: A Guide to Australian Spiders. Australia: New Holland Publishers Pty Ltd.
Gray, M. 1988. Australian Arachnology. Brisbane: A.D. Austin & N.W. Heather.
Hunter, H. 1982. The uffin Book of Spiders. Oxford Press.
Mascord, R. 1980. Australian Spiders. Tokyo, Japan: Charles E. Tuttle Co..
Overton, M. Feb. 9, 1998. Atrax Robustus, The Funnel-web Spider. Arachnids Weekly Digest, Vol. 1.