Wednesday, January 26, 2005

Secret of Venus flytrap's snap revealed

"LONDON - High-speed video and mathematical models have helped to unravel how a Venus flytrap is able to ensnare its victims.

Charles Darwin called the plant puzzle 'one of the most wonderful in the world.'

Since his time, scientists have pondered how the flytrap (Dionaea muscipula) is able to accomplish the feat without benefit of the nerves and muscles of swift animals.

Now researchers have found tensile strength is behind the plant's speedy clampdown on a hapless insect.

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.

Applied mathematics Prof. Lakshminarayanan Mahadevan of Harvard University and his team were able to follow the leaf action by painting dozens of fluorescent ultraviolet dots on the leaves.

They then filmed the leaves using a high-speed camera sensitive to UV to watch the leaves change shape during a snap.

How the plant seems to actively control the change in curvature within its leaves remains a mystery, but the study shows elastic strain plays a role in the process.

'In essence, a leaf stretches until reaching a point of instability where it can no longer maintain the strain,' Mahadevan said in a release.

A mathematical model filled in the details of when the plant snaps, how long it takes once stimulated and the timing of the steps.

Engineers hope to someday mimic the flytrap's ability in order to move tiny artificial devices that depend on minute movements of liquids or gases.

Moving valves, hydraulic sensors or time-released drug systems are some of the possiblities.

The study appears in Thursday's issue of the journal Nature."

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