zooplankton

https://doi.org/10.1351/goldbook.15139
Small floating or weakly swimming animals that drift with water currents and which, with phytoplankton, make up the planktonic food supply upon which almost all oceanic organisms ultimately depend.
See also: plankton
Source:
PAC, 2009, 81, 829. (Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)) on page 964 [Terms] [Paper]