Most plants obtain the foods they need to survive from photosynthesis, a process that converts light into other forms of useful energy; however, plants also need nutrients, such as nitrogen, which photosynthesis cannot provide. Although most plants are able to extract nitrogen from the soil around them through their root system, not all plants live in nitrogen-rich environments. They can't rely on a steady supply.

For some plants, the answer lies in a carnivorous lifestyle - basically, eating meat. These plants have special adaptations that allow them to hunt organisms such as insects, frogs, or even birds and rats, then digest them to obtain the necessary nutrients.

One of the smaller of the 600 or so species (yet one of the most widely known) of carnivorous plants is the Venus flytrap, whose leaves are effectively spring-loaded. Tiny hairs line the surface, and they are sensitive to touch. When an insect lands, the leaf snaps shut, trapping its victim inside. Glands inside the leaf then release a fluid that breaks down the soft parts of the insect's body; this material flows into the plant, and the nitrogen is absorbed. The leaf subsequently reopens, and the process begins again.