What causes the glow of luminescent sea life?

Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. read more

The deep-sea anglerfish lures prey straight to its mouth with a dangling bioluminescent barbel, lit by glowing bacteria. Attracting Mates Syllid fireworms can be found mainly on the seafloor, but they switch to a planktonic form to reproduce, where the females use bioluminescent signals. read more