plankton

American  

[plangk-tuhn] / ˈplæŋk tən /

noun

1. the aggregate of passively floating, drifting, or somewhat motile organisms occurring in a body of water, primarily comprising microscopic algae and protozoa.

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plankton British  

/ ˈplæŋktən /

noun

1. the organisms inhabiting the surface layer of a sea or lake, consisting of small drifting plants and animals, such as diatoms Compare nekton

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plankton Scientific  

/ plăngk′tən /

1. Small organisms that float or drift in great numbers in bodies of salt or fresh water. Plankton is a primary food source for many animals, and consists of bacteria, protozoans, certain algae, cnidarians, tiny crustaceans such as copepods, and many other organisms.

2. Compare benthos nekton

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Other Word Forms

• planktonic
  adjective

Etymology

Origin of plankton

1890–95; < German, special use of neuter of Greek planktós drifting, equivalent to plang-, variant stem of plázesthai to drift, roam, wander + -tos verbid suffix

Explanation

If you set your pet goldfish free in a lake, he might dine on plankton instead of the food you sprinkle in his tank every day. Or, more likely, he might be dinner for a bigger fish. Lakes, seas, and oceans are full of plankton, most of which is so small it can't be seen without a microscope. Anything that floats near the surface is considered to be plankton, whether it's an animal, plant, or something smaller like bacteria, and it's one source of food for fish and whales. The Greek root, planktos, means "wandering or drifting."

Example Sentences

See Examples For:

plankton

"Hurricanes carry moisture and move ocean currents and plankton," he said, noting the consequences for seafood dishes at his restaurant Huniik, where he reimagines Mayan specialties.

From Barron's ● Sep. 26, 2026

The Journal’s Jason Zweig points out that Buffett “fed on the tiniest plankton of the stock market” in his heyday, buying stakes in unloved, small companies.

From The Wall Street Journal ● Sep. 24, 2026

"This includes sea temperatures, the availability of plankton for feeding, which peaks during the summer months when it is warmer, and ocean currents."

From BBC ● Jul. 28, 2026

It lived in the ocean almost 600 million years ago and spent much of its life in one place, filtering plankton from the surrounding seawater for food.

From Science Daily ● Jul. 26, 2026

Because of the plankton and the cold, green waters, he might only be able to see twenty feet in front of him on an average day.

From "The Line Tender" by Kate Allen