Zooplankton are the heterotrophic (sometimes etritivorous) component of the plankton that drift in the water column of oceans, seas, and bodies of fresh water. The name is derived from Greek terms, zoon (ζῴον) meaning "animal", and planktos (πλαγκτος) meaning "wanderer" or "drifter". Many zooplankton are too small to be individually seen with the unaided eye.