Named after the benevolent Indian spirit Yuquiyu, El Yunque is the only rainforest in the U.S. National Forest System. Comprised of some 240 different species of trees, it is actually a series of forests, each one determined by its altitude. El Toro, the highest peak in the forest at 3,532 feet, has only odd dwarf vegetation clinging to its sides. Explore More>>
Coconut octopuses are among the most intelligent invertebrates around: They use tools, carry their shelters around for when they need them, and, fittingly, adopt an underwater walking motion that's very similar to humans.