The Venus flytrap (Dionea muscipula) is a carnivorous plant. As the name suggests, it does eat flies, but it also eats slugs, caterpillars, crickets, spiders and other insects. While the Venus flytrap gains most of its nutrients from the process of photosynthesis like any other plant, the acidic, boggy soil in which it lives is scarce in other necessary nutrients, such as nitrogen. Thus, the plant looks to insects and other living creatures to make up for what the soil lacks.
Open and Close
The leaves of the Venus flytrap work to trap and digest insects and other bugs. The process is both chemical and mechanical. The open leaves are coated with a sticky, sweet nectar, the scent of which attracts nearby insects. Each trap also has six trigger hairs on its surface. To set off the trap, the insect must brush two of these hairs, or one of the hairs twice, after which the leaves will close rapidly; in less than a second. This helps the plant differentiate between a non-living item, such as a twig, which would only trigger a hair once, and living items. If a hair is only triggered once, the trap will half-close, then slowly open again. While scientists do not fully understand the process by which the leaves close, the prevailing hypothesis is that the inner portion of the trap is comprised of a tightly compressed layer of cells, the tension of which keeps the trap open. The movement of the trigger hairs sets off a change (probably driven by adenosine triphosphate, or ATP) in the water pressure of the cells. The cells expand and relax, causing the trap to close.
Each trap is lined with cilia. These projections ensure an airtight seal when the trap is closed. This airtight seal keeps the insect fully inside the trap and protects the trap from mold or bacteria. After the trap closes, the plant releases digestive juices directly onto the insect. These juices break down the soft tissue of the insect, as well as destroy any bacteria that might have gained entry. The process takes between five and 12 days, depending on the size of the insect and the health of the plant. As soon as all of the nutrients have been absorbed by the plant, the digestive fluid recedes, the trap opens, and the remaining insect exoskeleton is washed out of the trap by the wind or rain.