plankton

Word family

• planktonic
  adjectiveC2
• phytoplankton
  nounC2
• zooplankton
  nounC2

Synonym discussion

Sense: noun/1

For noun sense 1, plankton names the tiny life in water that drifts with currents and often feeds larger sea animals. Microorganisms is broader: it can mean very small living things anywhere, including soil, food, or the human body. Algae overlaps with only part of plankton, because algae are plant-like forms and do not include tiny drifting animals. Marine life is much wider and covers everything from plankton to whales and coral. In science, people may also divide plankton into phytoplankton and zooplankton, but those are subgroups, not everyday replacements for the whole term. So you can say that sardines feed on plankton, that a pond sample contains microorganisms, and that sea turtles are part of marine life.

Common collocations

Etymology

Plankton entered English in the late 1800s from German Plankton, a scientific term built on Greek planktos, meaning 'wandering' or 'drifting'. The history matches the meaning, because plankton are carried along by water movement instead of traveling far by their own power.