Last week the Osaka Zoo, Japan, announced that one of the hippos it houses is not a male, as it had always presented it to visitors, but a female. The zoo managers noticed this seven years after the animal’s arrival in their facility: the reason is that it is not so immediate to understand the sex of a hippopotamus just by looking at it.
The hippopotamus in question is called Gen-chan and has lived in Osaka since 2017. Previously she was in a Mexican zoo, Africam Safari, where she was born. At the Osaka Zoo they had always believed that she was a male because that’s how she had been introduced to them by Africa Safari and initially there was no reason to think that she wasn’t true. Male hippos do not have a scrotum and their testicles do not descend outside the abdominal cavity; the penis also remains retracted inside the body when not erect. And the genitals of females are also hidden.
Gen-chan had arrived in Japan when she was 5 years old and male hippos reach sexual maturity around 7 1/2 years old, so initially her behavior also gave no clues that contradicted the Mexican zoo.
The Osaka Zoo began to have doubts because as time went by the animal was not doing anything typically masculine for a hippopotamus. A spokeswoman explained to the news agency AFP that among other things Gen-chan did not spread his feces around himself using his tail, as male hippos generally do to mark their territory, nor did he give mating calls to the female hippos in the zoo. Furthermore, those responsible for the care of the hippos had never managed to see male genitalia, although this in itself was not conclusive, because hippos are potentially very aggressive animals and for this reason a close observation was not advisable.
To resolve its doubts, the zoo ultimately commissioned a genetic test from an external organization and found that Gen-chan is a female. The zoo has decided not to change her name and has made it known that in light of this experience it will now carry out independent sex checks on its new animals to prevent something like this from happening again.
The shape of the hippos’ genitals on the one hand and their aggressiveness on the other are also among the reasons why it is very difficult to sterilize the approximately 160 hippos that live in Colombia and which descend from the 4 imported into the country from Africa by the drug trafficker Pablo Escobar , between the seventies and eighties.
In Colombia the hippos have found very favorable environmental conditions, as well as an absence of predators, and for this reason they have reproduced in large numbers and have become a problem: they devour the vegetation, take away space for the local animals, pollute the soil and the water, dig paths in the earth, change the flow and conditions of waterways, such as acidity and oxygenation. Among the species that cause damage with their presence there are, for example, manatees. The Colombian government plans to sterilize 20 hippos by the end of 2024 and 40 a year thereafter. The surgical operations to do this are expensive, as well as complex: each costs the equivalent of almost 10 thousand euros.
– Read also: The bewildering variety of penises in the animal kingdom
Tags: easy understand sex hippopotamus
