Melbourne has lost a much-loved gentle giant with the sudden death of Thembi the giraffe, with shocked staff struggling with the “tragic loss”.

Initial results from a necropsy (an animal autopsy) suggest the 11-year-old was startled, sometime on Wednesday evening, disrupting his normal blood flow and likely causing sudden heart failure.

Werribee Open Range Zoo, located in Melbourne’s west, had been Thembi’s home since 2009.

Thembi in 2009. Credit:Wayne Taylor

Keepers believe the incident which startled the giraffe happened in the walkway between the giraffes' night and day dens, where Thembi was found.