MANILA: Bertha, believed to be the world's oldest hippopotamus, has died aged 65, the Manila zoo said Monday, having beaten the typical lifespan for the mostly herbivorous mammals by decades, reports AFP.

The 2.5-tonne female was found dead Friday in her enclosure, with a post mortem examination concluding that Bertha, the zoo's oldest resident, had died from multiple organ failure, zoo director James Dichaves said.

"Bertha was among the pioneer animals here. Her mate died sometime in the 1980s and the couple failed to produce any offspring," he told AFP.