You searched for: “plankter
plankter (s) (noun), plankters (pl)
An individual or single member of all the tiny free-floating organisms that wander in fresh or salt water; such as, the seas and oceans: "As a student of planktology, Josh spent a great deal of time in the Pacific ocean near California trying to identify the varieties of plankters that randomly move from place to place in the water."
This entry is located in the following unit: plankto-, plankt-, -plankton (page 5)