Lived as a Male for 12 Years but Turned Out to Be a Female... This Animal Surprised Japan

Tennoji Zoo Hippo 'Genchan'
Gender Corrected from Male to Female

A hippopotamus in Japan, long believed to be male for 12 years, has been revealed to actually be female, causing a shock.

Osaka Tennoji Zoo hippo 'Genjjang'.
[Photo by Tennoji Zoo SNS]

On the 23rd, local media reported that 'Gen-chan,' a hippopotamus raised at Tennoji Zoo in Osaka, Japan, had its gender corrected from male to female after 12 years since birth. Gen-chan was transferred to Tennoji Zoo from a wildlife park in Mexico in May 2017 at the age of five. At that time, Gen-chan was classified as male, but the gender traits that should have become clear as it grew did not appear. In fact, the male reproductive organs did not develop.

Additionally, Gen-chan did not exhibit any typical male hippopotamus behaviors, such as making courtship sounds toward female hippos or wagging its tail like a propeller to scatter excrement. Suspicious, the zookeepers conducted a DNA test on Gen-chan, which revealed that Gen-chan was not male but a female hippopotamus.

The Tennoji Zoo stated, "At the time, we were told by Gen-chan’s Mexican caretaker that the gender was male," and added, "Upon later verification, the customs documents listed Gen-chan’s gender as female. It seems there was a mistake when the documents were transferred from customs to the zoo." Kiyoshi Yasuhuku, deputy director of Tennoji Zoo, bowed his head and said, "We realized how important it is to reconfirm gender and will be careful not to repeat the same mistake."

Cases of animals’ gender being changed have occurred frequently. In January, a giant panda named 'Heoye' at the Sichuan Chengdu Giant Panda Research Base was surprisingly identified as female rather than male. Heoye’s caretaker said, "When Heoye was born, the gender seemed closer to male," adding, "Heoye showed characteristics such as large urine volume, lively personality, and tall stature, so everyone was confident it was male. However, as Heoye approached four years old, male panda traits did not appear, so we conducted a DNA test, which showed Heoye was female."