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

Microscopic plankton are at the heart of the ocean’s food chain, feeding much bigger animals like whales. —Laura Baisas, Popular Science, 17 Oct. 2024

Invasive mussels are filter-feeders, sucking out nutrients and plankton that native species rely on for food. —Caitlin Looby, Journal Sentinel, 12 Sep. 2024

Colorado Parks and Wildlife broke the news of the mussels' arrival earlier this month after veligers, or larvae, were confirmed in plankton samples taken from several locations along the upper reaches of the river. —Shaun McKinnon, The Arizona Republic, 22 July 2024

The buildup of acid in ocean waters reduces the availability of calcium carbonate, a key building block for the skeletons and shells of corals, plankton, shellfish, and many other marine organisms. —Alan B. Sielen, Foreign Affairs, 15 Oct. 2013

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