phytoplankton
noun
phy·to·plank·ton
ˌfī-tō-ˈplaŋ(k)-tən 
-ˌtän
plural phytoplankton also phytoplanktons
: minute aquatic photosynthetic organisms (such as dinoflagellates, diatoms, and cyanobacteria) : photosynthetic plankton of freshwater or marine environments
Twenty to 40 different species of phytoplankton … can coexist within a single cubic centimeter of water, all vying just for light and a handful of nutrients.—
O. Baker
O. BakerPhytoplankton—myriad small, mostly unicellular algae and bacteria that occupy the surface waters of seas and lakes—dominate aquatic primary production, and over time they have radically altered Earth's atmosphere.—Robert Riding
Robert RidingPhytoplankton form the foundation of marine food chains, and their seasonal blooms are responsible for more than half the photosynthesis, and the resulting production of oxygen, that occurs on Earth.—Robin George Andrews
Robin George AndrewsAntarctic krill are thumb-sized crustaceans that feast on drifting phytoplankton …—Usha Lee McFarling
compare zooplankton
Usha Lee McFarlingExamples of phytoplankton in a Sentence
Recent Examples on the Web
During a bloom, environmental conditions cause microscopic phytoplankton to proliferate.
—Sarah Kuta, Smithsonian Magazine, 27 Mar. 2025
While there is no permanent human population on the remote island, South Georgia supports abundant life, from seals and penguins to tiny phytoplankton.
—Samantha Mathewson, Space.com, 11 Mar. 2025
Nutrients released from the melting iceberg can help support phytoplankton life, which in turn may aid carbon sequestration—the capture and storage of carbon dioxide—from the surface ocean to the deep, though scientists need to research this further.
—Thomas G. Moukawsher, Newsweek, 4 Mar. 2025
For phytoplankton, the organisms sink to the bottom of the ocean during dormancy, and they are eventually covered by sediment over time and preserved by the lack of oxygen.
—Julia Jacobo, ABC News, 1 Apr. 2025
See All Example Sentences for phytoplankton
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Sarah Kuta, Smithsonian Magazine, 27 Mar. 2025
While there is no permanent human population on the remote island, South Georgia supports abundant life, from seals and penguins to tiny phytoplankton.
—Samantha Mathewson, Space.com, 11 Mar. 2025
Nutrients released from the melting iceberg can help support phytoplankton life, which in turn may aid carbon sequestration—the capture and storage of carbon dioxide—from the surface ocean to the deep, though scientists need to research this further.
—Thomas G. Moukawsher, Newsweek, 4 Mar. 2025
For phytoplankton, the organisms sink to the bottom of the ocean during dormancy, and they are eventually covered by sediment over time and preserved by the lack of oxygen.
—Julia Jacobo, ABC News, 1 Apr. 2025
See All Example Sentences for phytoplankton
Cite this Entry
“Phytoplankton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phytoplankton. Accessed 5 May. 2025.
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phytoplankton
noun
phy·to·plank·ton
ˌfī-tō-ˈplaŋ(k)-tən
-ˌtän
: plankton that is composed of plants
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