From Burmese pythons to pygmy marmosets, there is a roaring illegal trade in animals online. A recent convention on the International Trade in Endangered Species found one rare species – the Kaiser's spotted newt (an orange and black salamander in the highland streams of Iran) – now numbers fewer than 1,000 adults in the wild because of internet trading. So what can you find on the internet? In just one day, I discovered dealers who appear to be selling some of the rarest species on earth.

Within a few hours, I was staring at an advert for one of the world's most endangered creatures. It read, "Very superb, jumbo size and most of all very rare". Only 200 mature ploughshare tortoises survive in the bamboo scrublands of north Madagascar; the rest, it seems, are online. And what would this pair of 30-year-old tortoises cost? £24,000, and a trip to Kuala Lumpur: there's no international shipping.

It is against the law to remove the critically endangered Burmese starred tortoise from the forests of Myanmar, but I easily found an apparent seller in Bangkok, Thailand. The dealer's picture features 35 turtles in a laundry basket lined with newspaper and wilted lettuce. Ten years ago, a survey by the Wildlife Conservation Society found few specimens in the wild. They did, however, find a tortoise trader in every village. This seller was asking £320 in cash for each specimen.

Bosc's monitor lizard and ball python



Bosc or Savannah Monitor (Varanus exanthematicus). Strong and hardy lizard species which comes from an arid habitat. Bites are very painful due to venom that pools around teeth and passes from monitor to prey. Photograph: Martin Harvey/Getty

One classified advert offered a "snake show" and "horse riding" along with Bosc's monitor lizards (£70) and ball pythons (£75). International law requires that these African species come with permits from their country of origin – conservationists worry that few wild-caught Bosc's survive to maturity in captivity and supplies are replenished from wild populations. The ad doesn't mention permits.

Elephant ivory



An African elephant in the Queen Elizabeth National Park in Uganda. Photograph: R Sobol/AP/International Fund for Animal Welfare

In 2008, eBay banned the sale of ivory, finding it impossible to ensure trade was legal. It's still available online, however. I called one dealer who seemed knowledgeable about the required permits; the same can't be said of many online sellers. Some nod to legality by claiming their ivory is antique; others don't bother. On Craigslist I found an "Endangered Species Ivory Neclace" [sic] in California ($120). The seller claims it's "circa 1980", but without a permit, there's no way to tell.

Hawksbill turtle



Photograph: DiMaggio/Kalish/Corbis

In Japan, artisans began carving hawksbill shells – the only true source of tortoiseshell – in the 1700s, but banned import of the critically endangered sea turtle in 1993. I found what appeared to be a tortoiseshell item on eBay: a "Brand New Takayama Ex-Takahashi Chikudo Model Shamisen Bekko Bachi Plectrum". It's a pic for a banjo-like Japanese instrument. The seller in New York promised a "natural material" of premium grade. Price $370, will ship worldwide.

Shahtoosh



A Tibetan antelope, or chiru. Photograph: George Schaller/World Wildlife Federation/AP

It takes the wool from five dead Tibetan antelope to make one shawl. That means you could get about 30,000 luxury garments from the herd estimated to remain in north-western Tibet. It's illegal worldwide to sell the wool, but I found an online dealer in Kashmir claiming to sell shahtoosh shawls along with "fancy wicker baskets". Price unlisted.

In the wild, the radiated tortoise spends its days munching cactus in the bushlands of southern Madagascar. "Sub zero", a dealer in Prai, Malaysia, has two that are two-and-a-half years into a life that can last for 100. This pair could outlive the population as a whole: scientists have predicted it is headed for collapse in the next half century because of habitat loss and the wildlife trade. Price £710 and £1,220, although Sub zero is offering a "mega discount".

Parrots and macaws



A Google search for pet birds turned up an eight-year old Tucuman Amazon (£450) in Canada. The seller claimed the bird is from the wild, which would make it illegal: after 20,000 Tucumans left Argentina in the 1980s to become pets, international trade in the species was banned in 1990.