They need only sunlight and certain nutrients for growth. Other kinds live more as animals do, and consume bacteria and other tiny organisms. Still other kinds change back and forth between a plantlike and an animallike lifestyle. Many possess thick cell walls that look like plates of armor. Some can even produce a chemical light called bioluminescence .
Dinoflagellates change form during their life cycle.
Most go through an active, swimming stage of life and a more stationary stage. In the stationary period, some dinoflagellates develop into thick-walled, seedlike forms called cysts . Scientists believe that cysts settle at the bottom of oceans and lakes, enabling dinoflagellates to survive when water conditions are unfavorable for growth. Dinoflagellates make up part of plankton, a drifting mass of water organisms. Plankton provides food for much sea life.