Question: does the salt in the ocean effect the animals in any way?

James Bell answered on 19 Jun 2014:

Yes definitely, blood and other fluids in an animal’s body have to be adapted to how much salt there is. In most of the sea, saltiness (salinity) doesn’t change a whole lot (only by a few percent and over long distances) but areas like estuaries or marginal seas like the Baltic, you see this change much more.

Changes in saltiness affect an animal through a process called osmosis. If the water surrounding a cell is saltier than inside the cell, water will move out of the cell to try and balance the difference (and vice versa). If you aren’t adapted to this then your cells could burst as the take on too much water or shrink as they lose too much. Most marine animals are restricted to where there is the right amount of salinity that they are adapted to but some animals have life histories that means they will change between fully saline seawater and zero salinity freshwater.

Fish like salmon spend most of their lives in the open ocean but they swim up rivers to lakes to breed. This means that throughout its life, a salmon is always adapting to how salty the environment is. Depending on whether it is in freshwater or seawater influences it’s behaviour and also things like how its kidneys function. To cope with this, Salmon often spend a few weeks in areas of mid-levels of salinity (like estuaries) just to slow down how quickly it must adapt to the new conditions.

http://www.unm.edu/~toolson/salmon_osmoregulation.html