More species of cacti have been identified in Big Bend National Park than in any other national park. Prickly pear cactus are the most common type of cacti found here, but in the lower elevations one can find other varieties such as cholla, rainbow cactus, eagle claw cactus, barrel cactus, and tasajillo. Shallow surface roots collect all available water, which the cactus stores in thick, waxy-covered pads, or stems. The pads are a good source of moisture, fiber, and nutrients for animals that brave the spines. Rodents bite into the edges of the pads between the spines, while javalinas have tough mouths that allow them to eat the entire pad, spines and all. The juicy ripe purple fruits are also a good food source for many animals.