World's oldest animal turns 175

Harriet was picked up on the Galapagos by Darwin and brought to England. She has spent the past 160 years in Australia, but her fame is about to become worldwide

She was born when slavery was still legal in Britain, and was an adult by the time of the American Civil War. She witnessed the invention of the bicycle and Morse Code, and helped Charles Darwin to formulate his theory of evolution. Her name is Harriet, and next week she celebrates her 175th birthday, the oldest creature on Earth.

A giant Galapagos land tortoise, Harriet lives in a spacious enclosure, complete with mud-bath and heated cave, on Queensland's Sunshine Coast. Darwin picked her up during his epic voyage aboard HMS Beagle, so the story goes, and transported her home to England. She was then taken to Australia, where she has ended up in a zoo run by Steve Irwin, the Crocodile Hunter, who infamously dangled his baby in front of a crocodile a couple of years ago.

Harriet was one of three tortoises collected by Darwin in the Galapagos; he called them Tom, Dick and Harry, believing them all to be male. They were only the size of dinner-plates back then, and thus escaped the indignity inflicted on adult tortoises by Darwin, who rode on their backs, rapping on their shells to persuade them to lumber along. Not the behaviour that one expects from one of the greatest scientific minds ever, but those were different times.

Harriet now weighs 150kg and is treated with the respect appropriate for a lady of her extremely advanced years. She receives a wash and rub-down from keepers at the Australian Zoo every morning, and is fed a nutritious vegetarian diet that includes courgettes, celery and green beans. For a special treat she is given red hibiscus flowers, which she adores – equivalent, perhaps, to a chocolate bar for humans.

The Guinness Book of Records cites her as the world's oldest living animal, not far off smashing the all-time record of 188 years, set by another Galapagos tortoise, now deceased. Harriet, whose correct gender was established only a few decades ago, was born in 1830, when Charles Dickens was still an 18-year-old lad.

Much of her lengthy life story is shrouded in mystery, for the only records documenting it were washed away in floods that swept Brisbane in 1893. Harriet was living at the time in the city's Botanical Gardens, where she spent nearly a century in the zoo after emigrating to the Antipodes in 1842.

But it appears that she was about five years old when HMS Beagle arrived in the Galapagos, bound for home after three years spent charting the coasts of South America.

Darwin, the ship's young naturalist, had already amassed a large quantity of specimens en route. But in the islands off Ecuador he found plants and animals that had developed in isolation from mainland populations and were noticeably different. Certain creatures, such as finches, even differed from one island to the next. The long-held view that species were fixed, and had not changed over time, appeared to be incorrect.

In this living laboratory, Darwin found the raw materials that would form the basis of his theories on evolution, natural selection and the origin of the species. The giant tortoises struck him because of their massive size and apparent longevity. He already had two in his collection when the Beagle dropped anchor off the island of Santiago. Now he was to add a third: Harry.

In his diary, he recorded his fascination for the species. "I was always amused when overtaking one of these great monsters, as it was quietly pacing along, to see how suddenly, the instant I passed it, it would draw in its head and legs and, uttering a deep hiss, fall to the ground with a heavy sound as if struck dead."

That Tom, Dick and Harry reached England intact was quite an achievement in an era when the tortoises were treated as long-distance stores of meat by seafarers, particularly whalers. Indeed, 50 of them were eaten by the Beagle's crew, including Darwin himself, on the journey home.

The trio were studied by Darwin as he worked on his theories, but they did not flourish in England, starved of the sunshine that they required for energy and reduced to a state of virtual hibernation. After enduring a series of freezing winters, they were transported to Australia in 1842 by the Beagle's former first lieutenant, John Wickham.

Wickham settled in Brisbane, where he held colonial offices including police magistrate, while the tortoises found lodgings at the Botanical Gardens. Dick died soon afterwards, while Tom survived until 1929; his embalmed remains are still in the Queensland Museum.

When the zoo at the Gardens closed in 1952, Harry was taken to a wildlife park owned by David Fleay, a Queensland zoologist who succeeded in breeding the platypus for the first time in captivity. Fleay was also, famously, bitten on the thigh by the last surviving thylacine, or Tasmanian tiger, a species now extinct.

It was during "his" sojourn at Fleay's sanctuary that Harry was examined by a visiting director of Hawaii's Honolulu Zoo and declared to be a she. Harriet, as she was known from then on, moved again in 1988, to the Queensland Reptile Park, which had been founded by Steve Irwin's father, Bob.

While Steve is not nearly as old as Harriet, he has become far more famous. An extrovert latter-day Crocodile Dundee type, he has exported himself around the world as the Crocodile Hunter, star of a television series and one feature film. He achieved notoriety of a different sort when he was photographed feeding a crocodile while holding his one-month-old baby son, Bob.

But while stunts like those may draw the crowds, Harriet is a big attraction at the zoo, where she leads a pampered existence around the clock. Never a fast mover, she spends most of her time being patted by zoo staff and slumbering on her outdoor bed of grass in the sun.

As with all the best stories, many of the key "facts" in this one are disputed. There is, sadly, no proof that the Harry who sauntered on to the deck of the Beagle in 1835 is the Harriet who wows visitors in Queensland today. DNA tests have verified her age, but her birth date, said to be November 15th, is a guess, based on the fact that turtles hatched in the Galapagos in November.

That will not deter the zoo from staging a birthday party for her on Tuesday. They plan to bake a massive cake for her to share with guests, and her enclosure will be filled with the red hibiscus to which she is so partial. Her fame is spreading; a children's book about her, Darwin's Tortoise, written by Robin Stewart, just been published.

Laura Campbell, the zoo's effervescent public relations manager, claims that a series of journalists who visited Harriet recently to write sceptical articles were utterly melted by meeting her in the flesh. At the end of the day, Ms Campbell believes, the truth of the link wth Darwin is immaterial.

"She's an absolutely incredible animal, whether she travelled with Charles Darwin or not," she said yesterday. "If the story was ever proved, it would just be the icing on the cake. As far as we're concerned, we've got the coolest animal in the world living right here."

Terri Irwin, Steve's wife, is similarly smitten. "She absolutely loves people," Mrs Irwin told the Australian Broadcasting Corporation. " She stands up really tall so you can scratch underneath her shell and feel her soft neck, and she puts her head out for something to eat, and she's got the most beautiful little eyes, and she's got little discs where her ears are and the softest skin on her head.

"And her great big shell has to be cleaned with cool water every morning because everybody uses her as a mobile rock. Lizards bask on her, birds perch on her, and so we clean everything off of her - so that she's nice and pretty."

Whether or not she personally inspired Darwin, Harriet is one of the last members of a dwindling species. Of the 15 sub-species of Galapagos giant tortoise that once existed, only 11 remain, all of them endangered and one on the brink of becoming extinct. As well as being hunted by sailors, they suffered from the release of feral animals which destroyed their food and ate their eggs.

Among the islands' present-day inhabitants is Lonesome George, the last representative of a sub-species found on Pinta Island. George has resisted three decades of encouragement to mate with females from a relatively close sub-species.

Despite all the publicity surrounding Harriet's birthday, zoo staff say the day will be relatively low-key. "With her being 175, we don't want to excite her too much," said Ms Campbell. "There won't be any table-top dancing."