A 12-year-old giraffe named 'Forest' at Australia Zoo has been named by Guinness World Records as the world's tallest living giraffe standing at 5.7 metres (18 ft 8 inches). "The process of measuring his (height) was far from straightforward...Staff had to create a specially marked measuring pole," Guinness said. The zoo is owned by late Australian conservationist Steve Irwin's family.