Because plants cannot move to escape danger, many have developed defense mechanisms. Most plants today have one or more defenses that include poisons, physical structures (tough branches; sharp, pointy leaves; spikes; or thorns), irritants (such as hairs, prickles, or oils that annoy the skin), and bad flavors (that can cause stomach pain and diarrhea). These defenses ward off predators (animals that want to eat them) and some defenses protect them from invading diseases. For example, waxy or tough leaves make it hard for bacteria or fungi to get into the plant. In addition, many bacteria and fungi rely on water to live, move, and reproduce. If the plant’s leaves shed water quickly, it is less likely that a disease-causing pathogen will be able to make its way into the plant.