Animals that use sight to navigate2 generally have a hard time getting around without light. Some, like owls, have very large eyes that they use to collect lots of light. They also use their other senses to gather information about their surroundings. Humans, on the other hand, have put a lot of effort into lighting their way by creating portable artificial light sources, from torches3 to automobile headlights. Bioluminescent life forms have an entirely different approach—they make light themselves and carry it around in their bodies.