Tarantulas
Whistling spider (Selenocosmia
species). Photo: R Raven ©
Queensland Museum
Introduction: The Australian tarantulas belong to the family Theraphosidae. In this family, there are nine species described from four genera, Selenocosmia, Selenotholus, Selenotypus, and Coremiocnemis. Tarantulas in Australia have often been called whistling, barking or bird-eating spiders because of the sounds individuals make when disturbed. The whistling noise is most often produced when the spider is disturbed and takes up a threatening defensive pose. This may act as a deterrent against predators.
Description: There is a large range in size of Australian tarantulas. Some species have a leg span of 5cm and the largest species may reach a body length of 6cm and a leg span of 16cm. Females are usually larger than males. In general, tarantulas have a large, heavy body, which varies in colour from dark chocolate-brown to pale fawn. As there are many species yet to be described in Queensland, it can be very difficult to identify individuals to species level.
Habitat and distribution: Species from the genus Selenocosmia are known from Queensland, New South Wales, South Australia and Western Australia. They inhabit many habitats ranging from rainforest to desert as but are not found in the southern coastal areas. Selenotypus are found in northeastern Queensland, Selenotholus in the Northern Territory and Coremiocnemis in northern Queensland.
Diet: Although tarantulas are often referred to as 'bird-eating spiders', they rarely eat birds. They are nocturnal, generalist feeders and their most common prey items are insects, lizards, frogs, and other spiders. Small hatchlings may be taken occasionally from nests on the ground.
Life history and behaviour: Adult female Australian tarantulas can live up to 20 years in web-lined burrows in the ground. Burrows can be quite deep, 40 – 60cm, and the width usually varies depending on the size of the spider. Some burrows may have a thin film of web around or across the entrance. Younger individuals and males, which are smaller than females, tend not to use burrows and are usually found in silk retreats under rocks and/or logs. The temperature of the burrow remains fairly constant, except in the warmer months from September to May. This is usually referred to as the feeding and growth season.
During spring and early summer, males search for females hidden in their burrows and entice them out to mate at the burrow entrance. Several days after mating, the female lays about 50 eggs into a 3cm diameter sac, which is stored in the burrow and protected by a tough cover of silk. After moulting once in the egg sac, the juvenile spiders leave the sac and moult a second time before leaving the burrow as free-living individuals. Males stop moulting once they reach sexual maturity while females continue to moult throughout their lifespan. Adult males can be distinguished by their swollen palps (pair of front sensory/mating organs).
Australian tarantulas are large spiders and can be much more aggressive than their South American relatives. If disturbed, individuals may 'rear up' and appear rather menacing. The bite is painful, as the fangs are large and can grow up to one centimetre long. Severe illness sometimes results and nausea and vomiting for six to eight hours have been reported from bites. These large spiders should not be handled. If someone is bitten, seek medical attention and collect the spider for positive identification.
Threatening processes: Collecting these spiders for the pet trade may have a negative impact on populations with an estimated 10 000 being taken annually from the wild in Queensland. By removing the large adults from small local populations, collectors may be inadvertently threatening species that have not yet been properly studied or described and that may have limited distributions.
What can be done to help these species?
People need to be aware that pet spiders can sometimes have originated from the wild. This threatens wild populations of tarantulas and wild collection should be discouraged. Also, do your bit to help protect habitats that are known to contain tarantulas.
Last updated: 01 September 2006
