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

Researchers from the Virginia Institute of Marine Sciences (VIMS) and William & Mary’s Batten School of Coastal & Marine Sciences were in Antarctic waters hoping to catch zooplankton. —Ryan Brennan, Miami Herald, 19 Feb. 2026

Phytoplankton establishes on the branches, which attracts zooplankton and insects. —Bryan Hendricks, Arkansas Online, 15 Feb. 2026

Marine microbes such as bacteria and phytoplankton form the foundation of ocean food webs, providing sustenance for creatures ranging from zooplankton to whales and supporting fisheries that feed billions of people. —Noah Lyons, San Diego Union-Tribune, 27 Jan. 2026

Those blooms then ripple through the food web, supporting zooplankton, fish, and higher predators, while also increasing the ocean’s capacity to absorb carbon from the atmosphere. —New Atlas, 22 Jan. 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