Pig Kidneys

Frog Kidneys

All animals that live in fresh water must cope with a continual inflow of water from their hypotonic environment. In order to maintain homeostasis of its extracellular fluid (ECF), the freshwater fish must excrete this excess water.

The excretory system consists mainly of the kidneys, which have a vital role in eliminating nitrogenous waste products metabolism by body cells. The kidneys also maintain homeostasis (a pig) by regulating the PH as well as balance of water.