Why do crystal jellyfish give out light?

Crystal jellyfish, like many other bioluminescent organisms, produce light through a chemical reaction involving luciferin, a light-emitting molecule, and the enzyme luciferase. This bioluminescence serves various purposes, such as deterring predators, attracting prey, and facilitating communication with other jellyfish. The light emitted can also help in camouflage, as it can match the light filtering down from the surface of the water, making them less visible to predators below.