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

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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

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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

Regulators should be doing more—not less—to protect the plankton.

From The Wall Street Journal ● Oct. 23, 2026

"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 whale shark is famous for being the largest fish on earth, Talwar said, but they have very small teeth and feed on plankton.

From Los Angeles Times ● Sep. 13, 2026

Hot weather increases plankton levels at the water's surface, drawing jellyfish up, experts say.

From BBC ● Aug. 27, 2026

Because, his brother Ahmad said, on moon-filled nights the plankton would be visible everywhere, spread out all over the sea, and the sardines could see and eat the glowing organisms with ease.

From "Zeitoun" by Dave Eggers

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