Australia is home to a variety of large, hairy spiders known as tarantulas. These arachnids are also commonly referred to by local names such as “whistling spiders” or “barking spiders” due to a unique sound they can produce. Australian tarantulas belong to the family Theraphosidae and represent the largest spiders on the continent.
Understanding the Classification of Australian Tarantulas
The common name “tarantula” in Australia is applied to a group of spiders within the family Theraphosidae. Most of the country’s described large species belong to the subfamily Selenocosmiinae, a group found throughout Southeast Asia and Oceania. There are currently seven officially described species in four genera, including Selenocosmia, Selenotholus, Selenotypus, and Coremiocnemis. Scientific understanding suggests the true number of species is much higher, with many remaining undescribed and awaiting formal classification.
The taxonomy of these spiders is complex, with ongoing research often resulting in name changes and reclassifications. Regardless of the specific genus, all Australian tarantulas are classified within the infraorder Mygalomorphae. This is a group of ancient spiders characterized by fangs that point straight down and move parallel to each other.
Key Species and Physical Characteristics
Australian tarantulas are characterized by a generally uniform color palette of browns, blacks, reddish-browns, or pale fawns, sometimes featuring a subtle silvery sheen. The largest species, such as the Queensland whistling tarantula, can reach a body length of up to 9 centimeters and a leg span of up to 22 centimeters, making them the biggest spiders in Australia. Their powerful fangs can be up to one centimeter long.
A defining characteristic of many Australian tarantulas is their ability to stridulate, which is the act of producing sound by rubbing two body parts together. This creates a distinctly audible hissing or whistling sound when the spider feels threatened. The genus Selenotypus contains the Australian featherleg tarantula, Selenotypus plumipes, which is uniquely identifiable by the long hairs on its rear pair of legs.
Venom Severity and Medical Risk
Australian tarantulas are venomous, but they are not considered life-threatening to humans, especially when compared to other medically significant Australian spiders. A bite is often painful due to the mechanical injury caused by their long fangs. The venom itself is not highly toxic to people, though it can still cause systemic symptoms.
Symptoms following a bite typically include severe localized pain and swelling at the site, followed by nausea, vomiting, and a headache that can last for several hours. The most serious medical risk is often related to a secondary bacterial infection from the puncture wound or a rare allergic reaction to the venom. The venom is known to be highly effective against smaller mammals, with bites potentially proving fatal to domestic cats and dogs within minutes or hours.
Geographic Distribution and Habitat
Australian tarantulas are widely distributed across the continent, preferring the warmer, more arid, and semi-arid regions. Their range spans across Queensland, the Northern Territory, Western Australia, and South Australia, with some species, like Selenocosmia stirlingi, reaching as far south as New South Wales and northern Victoria. They are found in a variety of environments, from tropical rainforests and coastal areas to open woodlands and deserts.
These spiders are primarily nocturnal and terrestrial, living in deep, silk-lined burrows that they excavate themselves. Female tarantulas are particularly sedentary, spending most of their decade-long lives inside these burrows, which can descend up to a meter into the ground. Encounters with people occur most frequently when the spiders are wandering in search of a mate, or if their underground homes are inadvertently disturbed.