Floating microscopic heterotrophs are mostly grouped as

Floating microscopic heterotrophs are mostly grouped as zooplankton. Heterotrophs are organisms that cannot produce their own food and must consume other organisms for sustenance. Zooplankton are small, floating organisms that play an important role in the aquatic food chain, serving as a food source for larger aquatic animals such as fish. Zooplankton can be either microscopic or macroscopic, and they can include a variety of different types of organisms, including small crustaceans, mollusks, and some types of algae. In contrast, phytoplankton are microscopic, photosynthetic organisms that form the base of the aquatic food chain, producing energy through photosynthesis and serving as a food source for zooplankton and other organisms.