zooplankton

noun

zoo·​plank·​ton ˌzō-ə-ˈplaŋ(k)-tən 

-ˌtän

plural zooplankton also zooplanktons

: freely floating or weakly swimming typically minute aquatic protozoans and animals (such as copepods, rotifers, and krill) or the eggs or larvae of aquatic animals (such as anemones, mollusks, and fish) : plankton composed of animals

… numerous varieties of adult gamefish depend on zooplankton for a substantial portion of their diets throughout their lives.

—Byron W. Dalrymple

Phytoplankton exhale life-giving oxygen and are consumed as food by zooplankton and small fish, which, in turn, are eaten by larger fish.

—Kenneth R. Weiss

Right whales eat zooplankton, which are tiny creatures that float along in the water column, by straining huge amounts of sea water through their baleen.

—Wendall Waters

compare phytoplankton

zooplanktonic

ˌzō-ə-ˌplaŋ(k)-ˈtä-nik 

adjective

zooplanktonic organisms

Examples of zooplankton in a Sentence

Recent Examples on the Web

Their diet is the most diverse of any of the smaller whales, eating over 100 species of marine and freshwater fish, mollusks, crustaceans, and zooplankton. —Kelsey Monstrola, USA Today, 17 Apr. 2026

Long roots create shelter for fish and insects and provide a home for zooplankton. —Jacob Wycoff, CBS News, 17 Apr. 2026

Rocks that make oil Oil and gas form from organic material such as marine zooplankton and phytoplankton, originally concentrated in shales, mud-rich limestones and other rocks exposed to elevated temperatures and pressures. —Scott L. Montgomery, The Conversation, 7 Apr. 2026

Those blooms feed zooplankton, which feed small fish, which feed larger fish like the walleye Feiner hopes to find. —Berly McCoy, NPR, 2 Mar. 2026

Word History

Etymology

zoo- + plankton

First Known Use

1897, in the meaning defined above

Rhymes for zooplankton

• nannoplankton
• phytoplankton

Kids Definition

zooplankton

noun

zoo·​plank·​ton ˌzō-ə-ˈplaŋ(k)-tən 

-ˌtän

: plankton that is composed of animals