Scientists discover Venus flytrap snaps shut through rapid cell wall softening

A research team led by physicist Yoël Forterre and postdoctoral researcher Jeongeun Ryu at Aix-Marseille University and CNRS has published findings in Science identifying the mechanism behind the Venus flytrap's remarkably fast closure. When trigger hairs inside the trap are stimulated, an electrical signal and calcium-ion wave spread across the leaf within a fraction of a second; the outer epidermal cell walls then soften by roughly 30–40% within about one second, releasing elastic energy stored in the pre-stressed tissue and causing the trap to snap shut via snap-buckling — analogous to a dome-shaped rubber popper toy flipping. To isolate this effect, the team immobilized traps with dental impression paste, used a nanoindenter to measure surface stiffness, and separately injected water into cells to time its transport, finding that water moves far too slowly — taking 30 to 60 seconds to cross the trap — to account for closure in under a second. Independent experts praised the work as extraordinary and novel, with biomechanics researcher Simon Poppinga calling it a 'breathtaking, very elegant paper,' while plant physiologist Sergey Shabala at the University of Western Australia raised objections, arguing that parallel rather than consecutive water transport could be fast enough and that no known biological mechanism could relax a cell wall on such a short timescale. The researchers acknowledge that the molecular trigger linking the electrical signal to cell-wall softening remains unknown, and plan further collaboration with biologists to identify it. Beyond basic plant science, the team suggests the principle of rapidly tuning material stiffness could eventually inspire soft robotic systems or smart adaptive materials.