This week in Biology, it was discussed that different organisms need different types of water for basic survival. This means. while animals are unique they can be organized by these traits. As was discussed, fish in particular have to have certain types of water to stay alive. Some fish strictly can only breath freshwater, while others can only breath types of saltwater. This is important to know. Fish who can only breath freshwater must stay in fresh water, because salt harms them. The same can be said about salt water fish. However, there are a select group of fish that can live and breath in both. One of these species is a fish called salmon. They spend half of their life in salt water and half of their life in freshwater. This makes them very unique.
However, not just salmon can do this. Other species like star fish, crabs, and lobsters can maintain a body to be able to handle the different types of water. A fish that uses salt water has to be careful in order to drink to mush salt. They have to use active transport inside of their bodies to remove the excess salt. Freshwater fish are risking drinking to much water and not enough salt. To combat this, they drink little water and urinate to keep and steady flow and healthy salt level.
JBSchool 