One of the plant world's most intriguing mysteries has been unraveled by researchers: how a Venus flytrap is able to trap its prey.
Using high-speed video and mathematical models, researchers found out that ‘tensile strength’ is behind the plant's speedy clampdown on a hapless insect.
Explaining the mechanism behind the flytrap (Dionaea muscipula), researchers said once trigger hairs are tripped by the prey, the plant bends its rubbery leaves into a convex shape, like a tennis ball or soft contact lens that has been flipped inside-out. The leaves instantly turn to a concave, as if the tennis ball is popped back to normal. The edges come together, trapping the insect inside.
To find out the answer to the mystery, Applied mathematics Prof. Lakshminarayanan Mahadevan of Harvard University and his team painted a field of dots on the outside of the leaf. From a video of the leaves clamping shut, they then tracked the path of each of the dots. This, in turn, allowed them to reconstruct the shape of the leaf at each moment, and build a computer model of the entire process.
They found out that the strain within the Venus flytrap leaf, probably created by water pressure, keeps the leaf poised near the point at which it will flip. Then, when an insect lands on the leaf and triggers an electrical signal, it takes only a tiny change in pressure to push the leaf over the brink, slamming it shut.
However, the exact mechanism the flytrap uses to change the pressures within the leaf remains unknown, Mahadevan said.
“We did not envision any immediate application of the work,” he said. But the insight might prove useful in microfluidics, a relatively new field concerned with creating devices that manipulate the flow of very small amounts of liquids and gases. The plant's ability to create a dramatic movement, without muscle, might inspire designs for such devices.
Venus flytraps - found in North and South Carolina and are fast becoming endangered - takes about 5 to 12 days to digest its prey by dissolving the insect’s soft inner parts.
