Baby Koalas Eat Something Truly Disgusting
Newborns aren’t very good at digesting stuff. We mammals have an alternative for babies who aren’t yet ready for real food: milk. All mammals drink milk when they’re first born, even the occasional weird mammal where no one in the species has nipples.
You could argue that there’s something gross about babies feeding off body fluids tapped right from their living mother. If a few red blood cells slipped into the breast milk, for example, we might find this vampirism deeply disturbing. But it’s not gross enough for koalas, who in addition to making milk, evolved another way of feeding their young.
Mother koalas produce something called pap. Koalas eat almost nothing but eucalyptus leaves, but baby koalas (who are called joeys, after singer Joey Fatone), aren’t able to digest the leaves, which are tough and also poisonous. So once the joey in the pouch starts transitioning off milk, it eats pap, eucalyptus leaves that the mother has already digested.
Are you picturing the mother vomiting into the baby’s mouth, like a momma bird? Sorry, the reality’s one step worse than that. The pap comes from the mother’s colon, popping out of the cloaca right after a load of feces, and then the joey engages in some coprophagia. To a layperson, pap is feces, but scientists point out that there’s a difference: Pap contains a whole lot more bacteria, live bacteria, which is essential for the joey to develop its own gut biome.
Very rarely are scientists able to observe the production of pap. Zookeepers have recently found themselves able to trigger pap production artificially, by manually stimulating the mother’s cloaca. The cloaca is also the koala’s reproductive opening, leading to the mother’s three vaginas, and you might not relish the thought of arousing the koala by rubbing it, but it’s all in a day’s work for a zookeeper.
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Top image: Benjamint444/Wiki Commons