Secret of the Venus Fly Trap Revealed

Image: COURTESY OF FORTERRE AND MAHADEVAN Taking just a tenth of a second, the snapping mechanism that a Venus fly trap uses to capture its prey is one of the fastest movements in the plant kingdom. Scientists have long wondered how the plant manages such a feat without muscles or nerves. The answer, according to results published today in the journal Nature, is by shapeshifting. Lakshminarayanan Mahadevan of Harvard University and his colleagues used high-speed video to catch the Venus fly trap in action. The researchers first painted the plant's leaves with ultraviolet fluorescent dots and then filmed them shutting under ultraviolet light. By analyzing the images and modeling the movement using a mathematical formula, the team reconstructed the geometry of the leaves as they closed. When trigger hairs on the leaves are disturbed, the plant moves moisture in the leaf in response. This, in turn, affects the leaf's curvature. "In essence, a leaf stretches until reaching a point of instability where it can no longer maintain the strain," explains Mahadevan. "Like releasing a reversed plastic lid or part of a cut tennis ball, each leaf folds back in on itself, and in the process of returning to its original shape, ensnares the victim in the middle."

A better understanding of the Venus fly trap's impressive system could help researchers lean to emulate it. The team speculates that similar muscle-free movement could applied to valves or switches in microfluidic devices or sensors. --Sarah Graham