Freshwater animals would need a well-developed excretory system in order to get rid of excess water from their bodies.
Fresh water is hypotonic to the cells of the body of freshwater animals. This means that water will always enter the body of freshwater animals by osmosis.
Without finding a way to get rid of excess water in their bodies, the body cells of freshwater animals will become turgid and lyse their contents, as situation that will lead to the death of the animals.
Thus, excess water that enters their cells by osmosis needs to be rid of and this requires a well developed excretory system.
More on freshwater adaptation can be found here: https://brainly.com/question/1564017
