A penguin couple living in a Tel Aviv zoo have turned out to be more sapphic than first thought.
Zookeepers discovered both penguins were female during a routine blood exam and closer examination at the Safari Zoo revealed their friendship had blossomed into something more.
Staff initially thought the penguins had gotten together because of a scarcity of males in the enclosure, but on closer inspection discovered there was a deep bond between the pair.
The couple display signs of a mating ritual by jumping on top of one another, keepers explained, showing how serious they are about each other.
They have even gone so far as to effectively set up a family home together, despite not being able to breed.
Homosexuality is a known phenomena with animals but according to Porat it is more common among males than females, at least among those in captivity.
"We heard about two males, but we never heard about two females so this is something very special," she added.
German broadcaster RTL reported three pairs of homosexual male penguins in Bremerhaven in 2009.