Here's a "sensitive plant" (genus Mimosa) I found while I was exploring down in Peru. Pretty cool, huh? This is one of the few plants capable of rapid movement. In response to shaking or touching, cells in the base of each leaflet quickly pump out water, causing the leaf to change shape and fold up. They unfold later, so while it costs the plant some energy, this doesn't harm it. Scientists think it's probably a defense mechanism to shrink away from or scare herbivorous insects and animals. You