Colo at Columbus Zoo
Colo, US' oldest known female gorilla, died at Columbus Zoo and Aquarium on 17 January Colombus Zoo and Aquarium

Colo, the oldest known female gorilla in captivity – who was also the first to be born in a zoo – has died in her sleep, Columbus zoo announced on Tuesday (17 January). Zoo authorities celebrated her 60thbirth anniversary in December 2016, as she surpassed the life expectancy of captive gorillas by more than 20 years.

Zoo officials said in a statement that Colo – a Western lowland gorilla – was the world's oldest gorilla in captivity.

Colo "was an ambassador for gorillas and inspired people to learn more about the critically endangered speicies and motivated them to protect gorillas in their native habitat," Tom Stalf, president and CEO of the zoo said.

He added: "At the Columbus Zoo and Aquarium out mantra is to touch the heart to teach the mind. Colo touched the hearts of generations of people who came to see her and those that cared for her over her long lifetime."

Colo was born in the zoo on 22 December 1956 and her 60th birthday was celebrated with immense fanfare, the zoo said in the statement.

She was diagnosed with malignant tumour in the recent past, which was operated and removed in early December 2016. Zookeepers and her doctors had said that she was recovering well from the illness, but are reportedly trying to determine the cause of her death.

"At that time surgeons felt they obtained clean, wide margins when they removed the mass [tumour] and until a necropsy (animal autopsy) is performed it is unknown if the cancer contributed to her death," zoo authorities said.

They added that her family and zookeepers spent time with her body on Wednesday morning, following which she was to be cremated and her ashes buried "at an undisclosed location in the zoo".

Colo gorilla at Columbus Zoo
Colo in a file photo from her childhood at Columbus Zoo and Aquarium Colombus Zoo and Aquarium