Answer These are microscopic organisms, similar to phytoplankton, who consume other plankton and digest waste. Some look like microscopic shrimp and others may look like tiny floating insects, depending on the type.
Phytoplankton are producers. They are like plants. They take in light and water and nutrients and put out energy. Phytoplankton do not eat any organisms, although they can cause things like red tides which would make it deabtable whether or not they are the direct cause of death.