Australia, a continent renowned for its diverse wildlife, often sparks curiosity and apprehension regarding its spider population. While the country is home to a vast array of spider species, the reality of their danger to humans is often less fearsome than popular perception suggests. This article aims to clarify the facts surrounding Australia’s spiders, distinguishing between common myths and scientific understanding.
Understanding Venomous Spiders in Australia
It’s important to distinguish between “poisonous” and “venomous” when discussing spiders. Almost all spiders are venomous, meaning they inject venom through a bite, typically to subdue prey. “Poisonous” refers to substances that cause harm when ingested or absorbed through the skin. Australia is home to approximately 2,000 spider species, but the vast majority pose little to no threat to humans. Only a small number are considered medically significant, capable of causing serious harm.
Fatalities from spider bites in Australia are exceedingly rare. There have been no confirmed deaths from spider bites in Australia since 1979, thanks to the development and widespread availability of effective antivenoms and prompt medical care. The risk of severe envenomation is low, and bites are usually manageable with appropriate first aid and medical attention.
Australia’s Medically Significant Spiders
Among Australia’s numerous spider species, the Sydney Funnel-web spider (Atrax robustus) and the Redback spider (Latrodectus hasselti) are the two most frequently cited as having significant medical impact on humans. The male Sydney Funnel-web possesses venom highly toxic to humans. These spiders are shiny and dark, ranging from blue-black to brown, with body lengths between 1 and 5 cm, and are known for their large, powerful fangs. They primarily inhabit moist, sheltered areas within a 160 km radius of Sydney, often found in burrows or around house foundations. A bite can cause immediate, severe pain, followed by symptoms such as sweating, nausea, vomiting, difficulty breathing, muscle spasms, and confusion.
The Redback spider, identifiable by the distinct red stripe on the female’s black, spherical abdomen, is found across Australia. The female, measuring about 10 mm in body length, is considerably larger than the male, which is only 3-4 mm. Redbacks reside in dry, sheltered locations like sheds, mailboxes, and under outdoor furniture, where they build untidy webs. Their neurotoxic venom causes intense localized pain that can spread, accompanied by sweating, nausea, vomiting, headache, and muscle weakness. While their bites can be severe, antivenom has been available since 1956, and no deaths have been reported since its introduction.
Other spiders, such as the Mouse spider (Missulena species) and White-tailed spider (Lampona cylindrata and Lampona murina), are sometimes mentioned as medically significant. Mouse spiders are stout, dark, and some species have distinctive red or orange heads. Their venom can be highly toxic, similar to funnel-webs, requiring similar first aid. White-tailed spiders are dark reddish to grey with a characteristic white spot on their abdomen. While their bites can cause localized burning pain, swelling, and itchiness, and rarely nausea or headache, scientific studies have shown no evidence linking them to severe skin ulceration, dispelling a common myth.
Safety and Dispelling Common Myths
Understanding how to prevent spider bites and what to do if one occurs is important for personal safety. To minimize encounters, wear gloves and closed-toe shoes when gardening or working outdoors. Regularly shaking out shoes and clothing before use, especially items stored outdoors, can also help prevent accidental bites. Installing flyscreens on windows and weather-strips on doors can deter spiders from entering homes.
First aid protocols vary depending on the spider. For suspected Funnel-web or Mouse spider bites, which are medical emergencies, apply a pressure immobilization bandage immediately to the bitten limb. The person should remain still while awaiting emergency medical assistance. This technique helps slow the spread of venom through the lymphatic system.
For Redback spider bites, wash the affected area with soap and water, and apply a cold pack to alleviate pain and swelling. Pressure immobilization is not recommended for Redback bites as it can worsen symptoms. For bites from most other spiders, cleaning the wound and applying a cold compress is sufficient. Seek medical attention if symptoms worsen. Always contact the Poisons Information Centre for expert advice if there are concerns about a spider bite.