This video clip shows the closure of the trap leaves of Dionaea muscipula, Venus Fly Trap.
This species of the Droseraceae, native only to parts of North and South Carolina, U.S.A.,
has a remarkable, specialized adaptation.

The blades are conduplicate and have long bristles along the margin.
There are 3, long trichomes on the upper (adaxial) surface of each leaf.
If two of these are mechanically agitated in sequence, e.g., by an insect,
the two halves of the leaf blade close rapidly, trapping the insect, which eventually dies.
Digestive glands on this adaxial leaf surface then release enzymes,
which break down the tissues of the insect into compounds that can be absorbed by the plant.

Carnivorous plants like this are often found in acidic, boggy habitats, where nutrients are limited.
Some have speculated that carnivory in these habitats functions to enhance nutrient availability,
e.g., of nitrogenous compounds.