Luciferin isn't what makes jellyfish glow, that's GFP. GFP, at least, requires a specific light input to cause the glow (UV at a particular wavelength depending on the molecule). I don't know about Luciferin, though.
Luciferin is what makes fireflys glow. Luciferin really produces light from chemical energy. GFP (Green Fluorescent Protein) is just fluorescent, not luminescent.
Luciferin is converted to a reactive intermediate by the enzyme luciferase in a reaction that uses ATP (produced by mitochondria), this intermediate reacts with O2 to produce light.
http://en.wikipedia.org/wiki/Luciferin