Venus flytraps can act fast enough to catch flies.
(marcouliana/iStock/Getty Images Plus)
To succeed in a hunt, a predator often needs to be faster than its prey.
Plants are not known for their speed.
Even so, one plant has evolved a snappy survival strategy that lets it feast on insects and arachnids that, by most measures, should be safe from its clutches.
We're talking, of course, about the famous Venus flytrap (Dionaea muscipula) – a plant that lures prey into a leafy trap, then snaps shut around the unfortunate victim, holding it fast while the plant digests at its leisure.
Scientists have long puzzled over the mechanism that allows this plant to move faster than plants should be able to.
Now, a team of researchers led by physicist Jeongeun Ryu of the French National Center of Scientific Research (CNRS) say they have identified the trigger.
To activate its jaws, the plant rapidly softens the cell walls in the trap's outer skin.
That change lets the outer surface expand more easily than the inner surface, bending the leaf until it reaches a tipping point and snaps shut.
https://www.youtube.com/watch?v=O7eQKSf0LmY
"This represents the fastest modulation of wall mechanics reported in plants," the researchers write.
"Our finding reveals a mode of plant motility based on dynamic tuning of material properties, suggesting principles for muscle-free, bioinspired actuation."
Many plants can achieve relatively timely and precise movement. One of the more famous examples is seen in Mimosa pudica, or touch-me-not, whose symmetrical leaflets fold shut when touched, a delicate maneuver thought to help the plant evade predation or minimize damage from passers-by.
For a lot of plants, these movements are powered by the flow of fluid – simple hydraulics that change internal pressure and thus the shape of the plant.
Previously, scientists had supposed that the mechanism behind the flytrap's movements was similarly hydraulic, but that posed a problem.
The traditional hydraulic idea was that the trap closes because water moves from one side of the leaf to the other, causing one side to expand more than the other and bend the trap shut.
(Paul Starosta/Stone/Getty Images)
The researchers identified two main flaws with this model.
The first is that water moves relatively slowly through plant tissue. The researchers measured how quickly water moves through a Venus flytrap and estimated that transporting water across the thickness of the trap would take between 30 and 150 seconds.
That's far too slow for the speed at which a flytrap needs to operate in order to grab its prey.
Sure enough, the movements that initiate closure occur on a timescale of about a second, much faster than water could move through the trap.
The other problem is that a water-driven mechanism should produce a delayed wave of motion across the trap as water gradually diffuses through the tissue. But the researchers found no sign of such a pattern.
Well, the next question naturally is: If not hydraulics, then what is it?
In their new study, the researchers described the two-stage process of a snap.
The first is the active bending phase, in which the trap begins to bend inward toward a critical tipping point. The second is the snap-closure itself, which takes just 0.2 seconds.
The researchers identified two main flaws with this model.
The first is that water moves relatively slowly through plant tissue. The researchers measured how quickly water moves through a Venus flytrap and estimated that transporting water across the thickness of the trap would take between 30 and 150 seconds.
That's far too slow for the speed at which a flytrap needs to operate in order to grab its prey.
Sure enough, the movements that initiate closure occur on a timescale of about a second, much faster than water could move through the trap.
The other problem is that a water-driven mechanism should produce a delayed wave of motion across the trap as water gradually diffuses through the tissue. But the researchers found no sign of such a pattern.
Well, the next question naturally is: If not hydraulics, then what is it?
In their new study, the researchers described the two-stage process of a snap.
The first is the active bending phase, in which the trap begins to bend inward toward a critical tipping point. The second is the snap-closure itself, which takes just 0.2 seconds.
How the trap snapped under different experimental conditions.
(Ryu et al., Science, 2026)
To isolate what kicks off the active phase, the researchers devised two tests. In the first, traps were cut into thin strips to hinder the snapping mechanism. Under this condition, the traps were still able to bend, but much more slowly.
In the second test, traps were clamped open and equipped with a force sensor to measure the force required to maintain separation between the two lobes. This produced a similar result, revealing a gradual bending motion that precedes the rapid snap-buckling stage.
The final piece of the puzzle was observing what the plant is actually doing during that active bending phase. The researchers used a tiny probe to measure the stiff, cellulosic walls of the cells inside and outside the trap before and after closure.
Cell walls on the inner surface barely changed – but those on the outer surface softened, losing about 40 percent of their rigidity.
A diagram illustrating the stages of the Venus flytrap trap closure.
(A. Fisher/Science)
So, here's how it works.
Before triggering, turgor pressure – the force inside a cell that pushes the cell membrane against the cell wall – is evenly distributed across the inner and outer walls of the trap.
When a crawling critter triggers the trap by touching one of the sensitive filaments inside it twice in quick succession, the outer wall softens.
That allows the outer surface to expand more readily than the inner surface, creating a mismatch that bends the leaf.
In a relatively short space of time, this bending passes the snap-instability threshold, and the lobes slam shut, allowing the plant to respond quickly enough to a trigger to snap up a lovely dinner.
Here's the wild bit, though.
That cell-wall softening is essentially how plants grow. Venus flytraps essentially dialed up a tool they already had in their genetic kit so they could take a more proactive approach to securing nutrients.
"These fine-tuned adaptations that allow plants to have the upper hand when interacting with animals raise another question – how can they arise from a trial-and-error evolutionary process?" writes bioengineer Jacques Dumais of the Adolfo Ibáñez University in Chile in a related editorial.
We now know how the Venus flytrap works its magic, but it hasn't lost its allure, not while those bigger evolutionary questions remain to be answered.
The Life of Earth
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