Some pitcher plants use raindrops and rapid movements to catch the prey in their pitfall traps, a new research suggests.
It is important to know that all plants move. Ulrike Bauer, a biologist at the University of Bristol in the United Kingdom said that:
“People usually don’t think of plants moving, because they usually move so slowly you need time-lapse cameras to see them move.”
The carnivorous pitcher plants have modified rolled-up leaves known as pitfall traps – which are deep prey-trapping cavities that contain digestive fluids which help liquefy the insects that fall in.
Nepenthes gracilis is a pitcher plant native to the humid tropical regions in Southeast Asia. In order to survive, the plant usually turns its prey into fertilizer.
Each pitcher plant has a ‘lid’ structure that is attached to hinged leaves. The lids have the purpose of preventing the water from getting into the pitchers and flooding them during heavy rain.
Scientists have now discovered that the lid of Nepenthes gracilis also helps the plant capture its prey.
Compared to other pitcher plants, Nepenthes gracilis produces much more nectar on the lid’s lower surface, according to previous research findings. Insects are able to walk on the lower surface of the lid to harvest nectar, but they usually end up in the pitcher because they get knocked off the lid due to the impact of falling raindrops.
In the new research – published October 5 in the journal Proceedings of the National Academy of Science – the researchers used sensitive laser equipment, as well as high-speed cameras to observe the plant vibrations.
They found that the lid of Nepenthes gracilis moved like a springboard when hit by the raindrops, thus launching the insects directly into the pitcher. The lids of other pitcher plants do not tend to vibrate when struck by raindrops – they often only bend.
In an experiment with simulated raindrops, the researchers found that 14 out of 37 ants fell from the lid of Nepenthes gracilis, compared with one out of 20 ants that fell from the lid of a pitcher plant called Nepenthes rafflesiana.
The lid of Nepenthes gracilis moves at five feet (one and a half metres) per second at peak speed. That is about ten times faster than a snapping Venus flytrap, the researchers said.
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