They may send a shiver down the spines of most people, but in Australia giant rodent-eating tarantulas are under threat of extinction from the pet trade. Despite their ferocious reputation, venomous bite and a penchant for tucking into everything from baby chicks to small rats, tarantulas - more commonly known as bird-eating, barking or whistling spiders - have become a popular pet and thousands of Australians keep them in cages and glass tanks. Selling for up to A$280 (HK$1,230) each, they are easier to keep than snakes or lizards and are widely available in pet shops. Experts estimate that unscrupulous collectors are removing tarantulas from the wild at the rate of 10,000 a year. In the wild they live for up to 25 years but in captivity their life span can be as little as five or six weeks. Dr Robert Raven, curator of spiders at the Queensland Museum in Brisbane, says science recognises five species of Australian tarantula but there may be another 20 species which have yet to be identified. 'The trade in tarantulas is completely unregulated. It is only illegal to take them from the wild if you remove them from a national park,' he said. It is, however, illegal to export the animals and there is a thriving black-market trade in shipping prized specimens to Europe and Asia, though most Asian collectors favour the more brightly-coloured species found in India, Sri Lanka and Southeast Asia, said Dr Raven. Worldwide there are about 800 species of tarantula. Australian tarantulas, which can grow to the size of a mouse, are among the world's most venomous. 'They can kill a dog or a cat within about an hour and if a person is bitten then they require immediate hospital treatment,' Dr Raven said. 'Their fangs are up to a centimetre long and they could quite possibly cut an artery. They are absolutely ferocious and will turn round and attack without provocation.' Dr Raven has appealed to the state government of Queensland, where most tarantula species are found, to put greater resources into spider research. 'The problem is most scientists are fully occupied with trying to conserve vertebrates. There is very little money for research into invertebrates. It's not a very chic area of science.'