Zooplankton

Animals (mostly microscopic) that drift freely in the water column.

A generic term referring to consumers that have limited ability to move against the current. Zooplankton can be permanent (i.e., rotifers or cladocerans) or temporary, as with the early life stages (i.e., eggs, larvae, juveniles, and adults) of many fish and invertebrate species.

Small, usually microscopic animals (such as protozoans), found in lakes and reservoirs.