Koala moms make their kids eat poo. It’s for their own good.

When it’s time to feed the kids, koala moms do their doody. Then the little ones snack on it.

Before you poo-poo the idea, a koala mom feeding a form of excrement to their young is a life-saving precaution called papping. 

“Pap is a different type of feces than their normal feces,” says Sally Bornbusch, a research associate at the Smithsonian’s National Zoo and Conservation Biology Institute. Adult koalas eat only eucalyptus leaves, which are toxic to most animals—and baby koalas, aka joeys, can’t digest them yet. 

When they’re born, koalas are less than an inch long, and they look more like a gummy bear than a koala bear. They make their way from the birth canal to mom’s pouch, where they will stay and nurse for about seven months. 

The babies don’t have the guts, so to speak, to break down those toxic and fibrous eucalyptus leaves. But pap provides joeys with the microbes, literally passed on from mom, “to digest complex plant fiber and probably to also start detoxifying some of those nasty compounds in eucalyptus,” Bornbusch says.   

Joeys instinctively know they’re ready to add pap to their diet, says Chris Massaro, senior vice president and chief zoological officer at ZooTampa at Lowry Park, in Florida, who helped welcome koala baby Sydney in 2019. 

Pap is “a mushy substance that’s produced in the cecum,” a part of the digestive tract beginning at the large intestine, he says. That mushiness makes it different in appearance from regular feces, which is pellet-like. 

At around 5 to 6 months old, when they’re still in the pouch, the joey is ready and starts initiating pap production. Like urine and feces, pap comes out of the mother koala’s cloaca, a multipurpose opening for the urogenital and digestive tracts, as captured on film recently in National Geographic’s new Underdogs series. 

“They joey will kind of hang down and stimulate down by the cloaca to get this pap out,” Massaro says. In short, koala moms are the world’s cutest soft-serve machines.

Within a few weeks, joeys start to experiment with eating leaves on their own, but will continue to nurse until they’re one year old.

Have your poo and eat it too

Bornbusch compares pap to the cecotropes consumed by both adult and baby rabbits, which allows them “to get a second crack at nutrition from their diet that potentially was missed during the first run at digestion,” says Erin Kendrick, clinical nutritionist at the Smithsonian Conservation Biology Institute.

Many animals, including guinea pigs, capybaras, and naked mole rats all produce and eat cecotropes. “They get sick and sometimes even die if they don’t eat the soft feces,” Bornbusch says. “It’s part of their natural ecology.” 

Bornbusch and Kendrick’s 2024 paper in the journal Animal Behaviour notes there are more than 150 species that consume their own regular fecal matter “at some point in their lives for nutritional reasons,” Bornbusch says, including juvenile animals, such as ostriches, iguanas, and African elephants. 

Adult animals who routinely order their meal “to go” include western lowland gorillas, leopard tortoises, and of course dung beetles, whose common name comes from their propensity to eat other species’ feces, which provides them with important nutrients and, remarkably, helps with waste management and keeping flying populations under control. 

Thankfully, there are always some folks that will go for seconds.

Underdogs will premiere on National Geographic June 15^th and stream the next day on Disney+ and Hulu. Please check local listings.