Which type of organism is not typically included when discussing freshwater ecosystems?

When discussing freshwater ecosystems, the focus is generally on organisms that directly inhabit or depend on freshwater environments. Fish, amphibians, and various insects are integral components of these ecosystems, living in or around water bodies such as rivers, lakes, and wetlands.

Fish are well-adapted to aquatic life, playing crucial roles in food webs and nutrient cycling within these ecosystems. Amphibians typically breed in freshwater and require it at various life stages, highlighting their dependence on these environments. Insects, including various aquatic larvae and adult forms, are also key members of freshwater ecosystems, contributing to energy flow and serving as food sources for other organisms.

In contrast, most terrestrial mammals are not typically discussed as part of freshwater ecosystems because they primarily inhabit land environments. While some terrestrial mammals may interact with freshwater systems (for example, by visiting to drink or reproduce), they do not reside in these ecosystems exclusively. Therefore, they are not considered integral to freshwater ecosystem discussions in the same way that fish, amphibians, and insects are.