The bladderwort (here Utricularia inflata) is an aquatic carnivorous plant with suction traps that move in less than a millisecond. Prey animals are sucked in with up to 600 times the gravitational acceleration, leaving no chance for escape.
Credit: Phillipe Marmottant
CAMBRIDGE: In less than a millisecond, bladderworts trap their prey with a suction force more than 10 times that experienced by any human, and could be the fastest plant on Earth, according to researchers who recorded them using high-speed cameras.
They might be the smallest known carnivorous plant, but bladderworts exhibit a highly sophisticated morphology, using underwater suction traps to snare food. Their trap door creates a suction swirl that causes accelerations of up to 600 g-force. The highest recorded gravitational force survived by a human is 46g.
“The most impressive thing is that the trap can trigger many, many times,” said co-author Phillipe Marmottant from the Laboratoire Interdisciplinaire de Physique in France. “The trap mechanism is so precise that it can repeat itself until the plant dies. It's a very reproducible mechanism.”
The anatomy of surprise
There are 220 species of the rootless bladderworts - or Utricularia plants – that are either aquatic or semi-aquatic, and can catch prey such as water fleas or small mosquito larvae at speeds incomprehensible to human perception. “If you look with the naked eye, you see an animal, then you see an animal in a trap, but you don't see what happens,” said Marmottant.
Their millimetre-sized traps have intrigued scientists since Darwin’s pioneering work on carnivorous plants, but the aquatic trapping mechanism has eluded explanation for some time due to the limits of camera technology and human visual perception.
To slow down the motion, the researchers used cameras that can take up to 10,000 pictures per second, with specific magnification and illumination devices to make the trap transparent. The resulting images seem to depict an elastic buckle in the concave walls, including a complete inversion of the trapdoor itself.
Process takes less than a second
To set the trap, the bladderwort pumps water out of its chamber, setting up a pressure difference between the inside of the plant and the water lying outside. Elastic energy is stored in the plant's body, awaiting release.
Then, when animals brush the hairs near the trap's entrance, the door opens for less than a millisecond, using a swirling suction to ingest any surrounding water, insects or small vegetation. The liquid – and any of its living inhabitants – then loop inside the vacuum for a few milliseconds, while any nutrients are slowly dissolved by digestive enzymes.
The entire process takes less than one second. If there is no prey to set the trap, it instinctively fires every five hours, resetting and regenerating itself, according to the researchers who published their findings in the journal, Proceedings of the Royal Society of London B.
