Phytoplankton are microscopic, photosynthetic organisms that float in watery environments and form the base of aquatic food webs. They include algae and similar tiny producers that convert light into chemical energy, supporting higher trophic levels. As a noun, the term denotes these planktonic plants or plant-like microorganisms collectively. The word emphasizes their plant-like (phyto) and drifting (plankton) nature.
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