Copepods, such as the one above, use there bioluminescence in two ways. They can be used to find a mate, or to distract a predator by shooting something like bioluminescence glue. It will then be stuck to a predatory fish, leaving it vulnerabile
Bioluminescence is a big thing to me, since I would like to get a career in marine biology. My favorite creature in finding nemo was the angler fish, and, as discussed, anglerfish use bioluminescence