phytoplankton

American  

[fahy-tuh-plangk-tuhn] / ˌfaɪ təˈplæŋk tən /

noun

1. the aggregate of plants and plantlike organisms in plankton.

---

phytoplankton British  

/ ˌfaɪtəˈplæŋktən, ˌfaɪtəplæŋkˈtɒnɪk /

noun

1. the photosynthesizing organisms in plankton, mainly unicellular algae and cyanobacteria Compare zooplankton

---

phytoplankton Scientific  

/ fī′tō-plăngk′tən /

1. Plankton consisting of free-floating algae, protists, and cyanobacteria. Phytoplankton form the beginning of the food chain for aquatic animals and fix large amounts of carbon, which would otherwise be released as carbon dioxide.

---

Other Word Forms

• phytoplanktonic adjective

Etymology

Origin of phytoplankton

First recorded in 1895–1900; phyto- + plankton

Example Sentences

These instruments measured fluorescence, which reflects energy released by phytoplankton when photosynthesis breaks down.

From Science Daily • Jan. 12, 2026

"As ice decreases in the future, we expect to see increased consumption of nutrients by phytoplankton in the Arctic, which has consequences for the food web," Pavia said.

From Science Daily • Nov. 13, 2025

She fed the zoae live phytoplankton and brine shrimp.

From Slate • Aug. 19, 2025

The creatures eat phytoplankton on the ocean surface which grow by transforming carbon dioxide into living matter through photosynthesis.

From BBC • Jul. 4, 2025

The phytoplankton, microscopic plants that float near the surface of water, had begun to remodel the lake into an environment that could once again sustain larger life.

From "Mountain of Fire" by Rebecca E. F. Barone