What are the two main types of freshwater organisms based on their mobility?

The distinction between plankton and nekton is fundamental in understanding the types of freshwater organisms based on their mobility. Plankton refers to organisms that are typically small and unable to swim against currents; they drift with the flow of water and are often carried along by tides or water movement. This group includes microscopic organisms such as algae and small zooplankton.

On the other hand, nekton consists of organisms that are strong swimmers and can navigate through the water independently of currents. Common examples of nekton in freshwater systems include fish, amphibians, and larger aquatic invertebrates.

Understanding these categories is crucial in aquatic science, as it helps in studying ecosystem dynamics, food webs, and organism behavior in freshwater environments. Other options present different categories that do not specifically pertain to mobility; for instance, benthic and pelagic refer to habitats rather than organism mobility, and producers and consumers classify organisms based on their role in the food chain rather than how they move through water.