# plankton

/ˈpɫæŋktən/ (US) · /plˈæŋktən/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/plankton
Updated: 2026-05-09

## Definition

tiny plants and animals that drift in the ocean or fresh water. They are a very important food source for many larger sea creatures like whales.

For teachers: a diverse collection of organisms that live in large bodies of water and are unable to swim against a current. Provides a crucial foundational role in aquatic food webs and the global carbon cycle.

## Examples

- Many whales eat tiny plankton to survive.
- The health of the local fish population depends heavily on the seasonal availability of plankton in the upper layers of the ocean.

## Usage notes

- Usually treated as a collective singular noun; occasionally used as a plural in scientific contexts to refer to different species.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.