plankton

noun

plank·​ton ˈplaŋ(k)-tən 

-ˌtän

plural plankton also planktons

: the passively floating or weakly swimming usually minute organisms (such as dinoflagellates, diatoms, copepods, radiolarians, and larval crustaceans and fish) of a body of water

Note: An individual organism found in plankton is technically referred to as a plankter.

… photosynthesizing plankton will grow at their intrinsic rates until nutrients become limiting, light is reduced by shading, and grazing organisms become abundant enough to check the increase …

—W. H. Berger

Almost all marine invertebrates, such as corals, clams, and starfish, reproduce by releasing microscopic larvae that drift in the plankton for a period ranging from minutes to months.

—Randy Olson et al.

Dense schools of menhaden … pour through these waters, toothless mouths … slurping up plankton and detritus …

—H. Bruce Franklin

The prolific zebra mussels have extremely efficient filtering systems, removing enormous quantities of plankton from the water …

—Nelson Bryant

see also phytoplankton, zooplankton

planktonic

plaŋ(k)-ˈtä-nik 

adjective

Other planktonic forms are grazers—tiny animals that filter algae and other organic matter out of the water and consume it.

—Wyoming Wildlife

Examples of plankton in a Sentence

fish that feed mainly on plankton

Recent Examples on the Web

According to the documents filed with Port Angeles, Ebb’s technology includes comprehensive monitoring, modeling, and reporting systems to track the chemistry of the seawater and health of the marine ecosystem, from tiny plankton, seaweed, and salmon to the largest orcas and humpback whales. —IEEE Spectrum, 26 Mar. 2024

Surprisingly, there were two very different sizes of plankton in their nets. —Laura Baisas, Popular Science, 17 Oct. 2024

But the method becomes more challenging when the water is not as clear, thanks to factors such as sediment or plankton, or the seafloor is not bright—perhaps because it is covered by grass. —Newsweek, 4 Nov. 2024

Unique to this species is a white band of denticles across its upper jaw, which researchers believe could reflect bioluminescent light from deep-sea plankton, potentially attracting prey in the dark waters where these sharks often roam. —Melissa Cristina Marquez, Forbes, 31 Oct. 2024

Word History

Etymology

German, from Greek, neuter of planktos drifting, from plazesthai to wander, drift, middle voice of plazein to drive astray; akin to Latin plangere to strike — more at plaint

First Known Use

1889, in the meaning defined above

Kids Definition

plankton

noun

plank·​ton ˈplaŋ(k)-tən 

-ˌtän

: the floating or weakly swimming animal and plant life of a body of water

planktonic

plaŋ(k)-ˈtän-ik 

adjective