Parameter Tree:
EARTH SCIENCE > BIOSPHERE > AQUATIC ECOSYSTEMS > PLANKTON > ZOOPLANKTON

Definition:
Zooplankton is the animal portion of the plankton; the animal community
in marine and freshwater situations that floats free in the water,
independent of the shore and the bottom, moving passively with the
currents. 


Reference:
Krebs, Charles K. Ecology - 4th ed. 1994. HarperCollins College Publishers,
New York, New York.