"She had been sick yesterday with, in effect, heart failure," Hangar told ABC radio.

"She had a fairly acute heart attack and thankfully passed away quietly overnight."

Hangar said Harriet, who had made it into the Guinness Book of World Records as the world's oldest living animal, had been credited with helping Darwin pioneer his theory of evolution.

"It's thought she may have been taken off there (Galapagos) by Charles Darwin," he said. "She's spent a period of time in Britain and found herself at the Botanic Gardens in Brisbane from about 1850 or 1860 onwards and eventually she found her way up to Australia Zoo."

Harriet was originally named Harry, as she was mistakenly identif...

"She had been sick yesterday with, in effect, heart failure," Hangar told ABC radio.

"She had a fairly acute heart attack and thankfully passed away quietly overnight."

Hangar said Harriet, who had made it into the Guinness Book of World Records as the world's oldest living animal, had been credited with helping Darwin pioneer his theory of evolution.

"It's thought she may have been taken off there (Galapagos) by Charles Darwin," he said. "She's spent a period of time in Britain and found herself at the Botanic Gardens in Brisbane from about 1850 or 1860 onwards and eventually she found her way up to Australia Zoo."

Harriet was originally named Harry, as she was mistakenly identified as male, an error which was not rectified for more than a century.