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Plants get most of their food from sunlight and air, but they also need nutrients like nitrogen to survive. And in parts of the world where the soil doesn’t have a lot of nitrogen, some plants have evolved a pretty macabre way to meet their needs: they kill and eat animals.

And it turns out that some carnivorous plants in Borneo go to even more extreme lengths to get their fix. They’ve gone back to playing nice, at least with some creatures, in exchange for a precious, nitrogen-rich resource: animal feces. Nepenthes is a genus of pitcher plants: carnivorous plants that make pitcher-shaped traps.

But in one species, the fanged pitcher plant, these traps are home to diving ants. Pitcher plants colonized by these ants have bigger leaves and a greater number of leaves, which make them more efficient at photosynthesis. And in order to grow more leaves, plants need more nitrogen, since it’s a key component of many cellular building blocks.

In fact, researchers estimate that fanged pitcher plants occupied by diving ants contain 200% more nitrogen! So, they really seem to benefit from these ants. At first glance, that seems weird, given that diving ants form their colonies inside the long hollow tendrils that the pitchers hang by, and they feed on the nectar that trickles out of the namesake teeth on the pitcher’s rim.

So their very presence costs the plant resources. Plus, they straight up steal the plant’s prey. The plant’s digestive juices aren’t that great at breaking things down.

And as their name suggests, these ants can dive into this weak digestive soup to fish out partially-eaten bugs before the plant has the chance to finish them. But they do actually help the plant in several ways. Like, they hunt other insects that hang out in the traps and munch on what the plant has caught.

Also, they hide under the pitcher’s rim and ambush insects as they land. And since they’re kind of messy eaters, they end up dropping bits that fall into the pitcher, which are way easier for the plant to digest. But most importantly… these ants poop directly into the pitcher juice, and by doing so, they give back some of the nutrients they borrow when they fish bugs out of the trap.

And that’s actually where most of that extra nitrogen comes from! Now, the fanged pitcher isn’t the only Bornean pitcher plant that’s figured out feces are full of nutrients. Some species partner with much larger poopers.

For example, Low's pitcher plants. When they’re young, they have typical pitcher traps. But as they mature, they start growing weirdly-shaped ones instead.

These new pitchers have a lid that secretes more nectar than any other Nepenthes species. And this nectar attracts the local mountain tree shrews, big-eyed rodents about 18 centimeters in length. The thing is, the only way the tree shrews can get the nectar is by positioning their rump right inside the pitcher.

And it just so happens that this species of shrew marks places where good food can be found with poop. So, as they’re licking off the nectar, the pitcher plant gets lots of nitrogen and other nutrients. Scientists found that this close relationship between pitcher plants and shrews also occurs in two other species.

All get up to 100% of their nitrogen from tree shrew poop! Though, each uses a slightly different setup to trap the shrew’s butt in the right place.  And even though more research is necessary, scientists hypothesize that the plants also evolved a mechanism to protect the structure of immature toilet pitchers from shrews until they’re sturdy enough to support their butts. The fully-mature shrew toilet takes on a dark purple hue that the tree shrew can actually see, so it’s thought the color signals that the nectar toilet is open for business.

And what’s cool about all this is that though these tree shrews are small by human standards, they’re not extremely tiny.  So the pitchers of these plant species are big, so big, that they make them the biggest carnivorous plants known to science!  Still, when it comes to pitcher reshaping, they’ve got nothing on their cousin, Nepenthes hemsleyana. Its pitchers grow a peculiar lid shaped sort of like a bat’s ear.  In fact, researchers discovered that, much like an actual bat’s ear, this structure is a perfect reflector of the ultrasound cries that bats use for echolocation. And there’s a good reason for that.

You see, Hardwicke's woolly bats roost in the pitchers. The pitcher walls shield them from the scorching sun during the day and keeps their skin free of parasites, since the noxious critters can’t lay their eggs on the pitcher’s waxy surface.  The pitchers are also shaped in a way that prevents the bats from completely slipping inside, and the plant actually limits the amount of digestive juice in the pitcher so that it doesn’t touch the bats’ behinds. So they’re quite the cozy place to roost.

And Nepenthes hemsleyana, in turn, receives the guano the bats release as they sleep. This mutualistic relationship explains that ear-like lid shape. In the Borneo swamp forest, it might be difficult to find the one species of pitcher plant that really wants you to snuggle in for a day of sleeping and pooping.

But because of the highly reflective, ear-shaped lids, bats can use their echolocation to navigate to these special pitchers, no matter how much other greenery surrounds them.  Whether we’re talking about their partnerships with bats, ants, or tree shrews,. Nepenthes pitcher plants remind us that there’s no one way to have a nutritious diet.  And one organism’s waste can always be another one’s treasure.  Thank you for watching this episode of SciShow! And a special thank you to our channel members here on YouTube.  The support of our channel members helps us keep making fun, freely available educational science videos like this one.  So thank you!

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