Electrical impulses aren’t exclusive to animals. Plants such as the Venus Flytrap also use electricity to sense and react to the world. In this experiment, you’ll record action potentials from a Venus Flytrap and discover how a plant knows it’s an insect moving inside the trap.
The Venus Flytrap is a carnivorous plant that supplements its diet by trapping and digesting insects—an ingenious solution to the nutrient-poor, boggy soils of the Carolinas. Instead of growing deep roots to find scarce minerals, the Flytrap hacked nature by extracting nutrients from animals.
How can a plant sense a fly and capture it? That sounds like something an animal would do. Do plants have brains? What even counts as a brain? In this experiment, you’ll tackle these questions and uncover the physiology behind the Flytrap’s lightning-fast snap.
Materials:
Insert the black ground pin into the pot’s soil so the Plant SpikerBox has a stable reference.
The recording electrode goes on the trap (the leaf), while the ground stays in the soil. Press the orange stake electrode into the soil next to the trap you want to record from, so its silver wire rests against the outside of the trap. Put a dab of electrode gel where the wire touches the trap.
Connect the yellow lead to the Plant SpikerBox, red clip to the stake wire, and black clip to the ground wire. Power on the SpikerBox and launch SpikeRecorder.
Begin recording. Gently touch one of the trigger hairs inside the trap (there are three on each side, about six in total). Wait about 60 seconds between touches. The trap only snaps shut when two touches come within about 20 seconds of each other—that’s how it tells a moving insect from a raindrop—and closing a trap over and over can kill it.
Examine your recordings. Do you see spikes that resemble action potentials? How do their shapes and timing compare with those recorded from animals such as the cockroach leg? Observe the Flytrap’s behavior when you touch a trigger hair. Does it always respond? What patterns can you spot in the electrical signals and the trap’s movement?
