A Venus flytrap doesn’t have a brain, but it can count - and scientists have nailed down exactly how. The trap’s inner surface has stiff trigger hairs. Each touch sends an electrical signal through the leaf. The plant remembers these signals for about 20 seconds, basically holding a running total.
Touch one is “maybe.” The plant starts a count. Touch two within 20 seconds is “definitely an animal” - snap! The jaws close. But the trap doesn’t seal tight yet. It waits for more wiggling. Touches three and four make it squeeze harder. After about five touches, it commits to full digestion and starts pumping out enzymes.
This careful counting saves the plant huge amounts of energy. Closing a trap and producing digestive juice is expensive, and a raindrop or blown leaf would otherwise waste a meal’s worth of effort. The five-touch rule basically means: “Is this thing definitely alive and worth eating?”
