These carnivorous plants are hunting underground

In the 1990 horror comedy Tremors (now streaming on Peacock!), Valentine McKee (Kevin Bacon), Earl Bassett (Fred Ward), and the rest of the residents of Perfection, Nevada, find themselves at the mercy of a strange species of massive underground worms.

The animals, not-so-lovingly referred to as Graboids, tunnel their way through the Earth in search of anything they can fit inside their gaping mouths. While we don’t expect them to be quite so large, we’re comfortable with the notion of predatory animals dwelling beneath our feet, swallowing up prey wherever they can find it. We expect our plants, however, to stay where we can see them and peacefully transform sunlight into oxygen. Somehow, a new species of carnivorous pitcher plant missed the memo.

Scientists from Palacký University, and collaborators, have discovered a new species of pitcher plant, known as Nepenthes pudica, which sets its traps underground and gobbles up subterranean prey. The new species is described in the journal PhytoKeys.

There are approximately 160 species of pitcher plant, all of which hail from the genus Nepenthes, which rely on what scientists call pitfall traps. They work by secreting nectar or using visual lures to attract prey, typically invertebrates like insects, but occasionally small vertebrates like reptiles and rodents. The rim of the pitcher acts as a sort of leafy event horizon. Once over the point of no return, moisture from condensation or additional nectar causes the prey to slip inside where they drown and are slowly devoured.

Generally, pitcher plants produce their traps — which are modified leaves which have curled in on themselves — above ground, and rely on flying or crawling insects to find them. Before now, there were no known pitcher plants which claimed subterranean hunting grounds. Nepenthes pudica’s unique resource acquisition strategy changes that.

Scientists found the plants in five regions in the lower montane rainforest of North Kalimantan Indonesia growing near large trees. Those trees send their large, branching roots into the soil and, when the trees die or their roots shift, they leave soil cavities behind. Nepenthes pudica exploits these soil cavities and lays their pitchers down inside them, but they aren’t wholly passive. If no soil cavities are present, this enterprising plant isn’t above making them itself.

It will build its pitchers directly in the soil or else beneath leaf litter or mossy coverings. They subsist mostly on ants which stumble into the pitfall traps while excavating underground, but scientists discovered other invertebrates in their soup death traps, as well, including mosquito larvae, nematodes, and annelids (worms).

Interestingly, some of the larvae didn’t show signs of digestion, indicating that they might be able to survive inside the pitchers. That’s not wholly unheard of. Other species of nepenthes have a symbiotic relationship with some larvae. The larvae live inside the liquid of the pitcher and eat the other insects which fall inside then they secrete nutrients which the plants consume.

Carnivorous plants were weird enough already, having already flipped the script on the predator-prey relationship. Moving underground, far from the shining light of the Sun, pushes them into another realm entirely. It just goes to show that nature is a whole lot weirder than we sometimes give it credit for.