These, Dr Mincer and Dr Amaral-Zettler found in the form of dinoflagellates, some of which like to snack on smaller creatures to supplement their photosynthesis.
Left alone, dinoflagellates won't produce much light, but if something like an ocean wave, a current, or a human disturbs them, they will flash brightly.
If you're a single-celled organism like a dinoflagellate, you're at the bottom of the food chain, so avoiding getting eaten involves hard work every day.