Bioluminescent creatures are organisms that produce light through chemical reactions within their bodies. This natural phenomenon can be found in various species, including certain types of jellyfish, fireflies, and deep-sea fish. The light they emit can serve different purposes, such as attracting mates, deterring predators, or luring prey. These creatures contain special proteins and enzymes that facilitate the light-producing reaction, often involving a molecule called luciferin. Bioluminescence is most commonly observed in dark environments, like the deep ocean, where it can create stunning displays of light. Scientists study these organisms to understand their biology and potential applications in medicine and technology.