None of them can lay an egg, but the heart wants what the heart wants and two sets of male penguins have coupled up this nesting season at Melbourne aquarium.

The aquarium has announced the same-sex duos of Tiger and Branston and Jones and Klaus are among its latest gentoo penguin partnerships.

Lead bird keeper Tanith Davis said the aquarium often fostered eggs to male-male penguin pairs and same-sex couples were not unusual in the animal kingdom.

“Same-sex penguin pairs will court each other and incubate an egg exactly the same way as a male-female pair,” she said.

“As male-male pairs can’t lay their own eggs, we will sometimes foster an egg to them from another pair.

“Sea Life Melbourne has had many same-sex couples in our breeding history, and they have been doting parents.”

Gentoo penguins nest once a year just before the start of spring, with both sexes sharing parenting duties and collecting rocks to build a comfortable home for their eggs.

Same-sex sexual behaviour has been observed in over 1500 animal species, according to a 2019 study published in peer-reviewed online journal Nature Ecology and Evolution.

-AAP