Many "active" carnivorous plants require vast stores of energy to trap insects, while "passive" species tend to wait until insects get trapped of their own accord. But Nepenthes gracilis -- an unusual species of pitcher plant-- has other ideas: it uses the energy of raindrops to fling ants into its jug-shaped leaves.
How does it work? Nepenthes gracilis has a particularly rigid "lid" to its pitcher (compared to other related species). This means that when a raindrop strikes the lid, it turns into a vibrating springboard that launches any onboard ants into its maw (and the digestive juices waiting therein). Further, this plant's lid has special wax crystals that reduce friction-- making it harder for ants to hold on.
Because N. gracilis uses an external power source, it achieves velocities that are an order of magnitude faster than the iconic "jaws" of Venus flytraps or the sundew's catapult tentacles. The tip of the lid moves at a staggering 1.5 m/s.
This study joins a growing body of work that overtunrs classic notions about carnivorous pants. Just in the past few years, we've seen
- a pitcher plant that "talks" to bats to entice them to spend the night in the pitcher (and give the pant nutritious guano)
- genome sequencing of the Venus flytrap, indicating that "the plant may have imported from its insect prey nerve-related genes that in turn allowed the plant’s trapping mechanism to shut faster."
- at least nine independent origins of carnivory in plant species between 8 and 72 million years ago.
What will we find next?
A carnivorous pitcher plant uses power from falling raindrops to fling ants to their doom, biologists have discovered. The team, from the University of Bristol, found that raindrops kick off very fast vibrations in the lid of the plant's jug-shaped leaves. This propels ants from the lid into the pitcher trap below, where they drown and are consumed by digestive juices. The findings, published in the journal PNAS, are based on high-speed cameras and laser vibration measurements.