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 arrow worms) 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 short, fine tentacles help capture prey such as zooplankton and small crustaceans. —Neetika Walter, Interesting Engineering, 20 Aug. 2025

According to the Aquarium of the Pacific, the jellies feed primarily on zooplankton. —Laylan Connelly, Oc Register, 20 Aug. 2025

The basin is an ideal test site, according to Subhas, because there is little presence of phytoplankton, zooplankton, commercial fish larvae, and endangered species, including some whales, during this season. —ArsTechnica, 11 Aug. 2025

But there’s also phytoplankton and zooplankton — microscopic plants and animals living in the water. —Sheryl De Vore, Chicago Tribune, 22 July 2025

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