What are microscopic animals that swim or drift near the surface of aquatic environments called?

Microscopic animals that swim or drift near the surface of aquatic environments are referred to as zooplankton. These organisms play a crucial role in aquatic ecosystems as they serve as a primary food source for larger species, including fish and other aquatic animals.

Zooplankton include a diverse group of organisms, such as small crustaceans and the larval stages of various animals. Their presence near the surface allows them to take advantage of the light and nutrients available in this zone of the water, as well as to be accessible to their predators. Understanding the role of zooplankton is vital for studying food webs and the overall health of aquatic environments.

In contrast, phytoplankton are primarily plant-like microorganisms that use photosynthesis to create energy, benthic organisms are those that live on or in the bottom substrates of aquatic environments, and macroinvertebrates are larger invertebrates that are typically visible without a microscope. These distinctions highlight the importance of understanding the specific characteristics and roles of different groups within aquatic ecosystems.