Luminous organisms are living beings that produce light through a natural process called bioluminescence. This phenomenon occurs in various species, including certain types of jellyfish, fireflies, and deep-sea fish. The light is generated by chemical reactions within their bodies, often involving a molecule called luciferin and an enzyme called luciferase. These organisms use their light for various purposes, such as attracting mates, deterring predators, or luring prey. Bioluminescence can be found in both marine and terrestrial environments, showcasing the diversity of life on Earth. Scientists study these organisms to understand their biology and potential applications in fields like medicine and environmental monitoring.