The Venus Fly trap plant (Dionaea Muscipula) is found in the southeastern USA. It is a carnivorous plant (eats insects and such) in addition to a plant-like metabolism (absorbing nutrients from the ground, and photosynthesis). Uptil now, the mechanism of its insect-trapping operation was not clear, since the plant does not have a nervous system or any muscles or tendons.
Lakshminarayanan Mahadevan and colleagues (Yoël Forterre, Jan M. Skotheim, Jacques Dumais) have written a paper in Nature explaining how the Venus flytrap is able to snap shut almost instantaneously.
Since the plant lacks any kind of nervous system, it achieves this trapping feat through hardware. When the insect lands on one of the leaves, it excites the small hairs on its surface. This moves water inside the plant leaves, which changes the curvature of the leaves. This causes the leaves to gain some elastic energy, which they lose by closing on the hapless insect. It then takes hours for the leaves to open, by which time the insect is dead, and digested. The exoskeleton of the insect is not digested, and it falls away as the leaves reopen.
Mahadevan developed a mathematical model to describe the movements, and used a high-speed ultraviolet video to observe the movements of the leaves. He had to excite the same hair on the leaf twice within a time period of 10-15 seconds in order to get the leaves to close. This enables the plant to avoid a false alarm.