Why can't starfish live in freshwater?

Starfish Distribution. All of the oceans around the world are home to the Starfish. They can only thrive in saltwater. They aren't able to live in freshwater due to the amount of calcium that they need to create their bodies. The largest number of them is found in theIndo-Pacific Ocean region. read more

Best Answer: Starfish, an echinoderm does not have excretory system. Hence they are not capable of performing osmoregulation. They keep the salinity isotonic with surrounding sea water. In freshwater they will be flooded with water and will be in position to expel the excess of water. That's why starfish can not survive in freshwater. read more

Saltwater fish are evolved to deal with water constantly rushing out of their bodies. The salt in the surrounding water exerts what is called osmotic pressure on the fish. read more