The commonly known example is the penguin. It has a suborbital gland that converts sodium chloride out of the bloodstream where it's excreted as a brine on the bill. Penguins don't actually drink salt water, but they ingest it while swallowing prey.
I know of only two the bull shark and the salt and fresh water alligator.
probally fresh because no salt in mouth or eyes addition: it is easier to float/swim in seawater since seawater is denser than fresh water.
97% seawater, other 3% is freshwater.
by evaporation
No, it is seawater.
the seawater smells
clean fresh water should be used strate away to prevent infections
A lower freezing point than fresh water
no.they must have fresh water to live.
Flash Distillation
You've already answered your own question. The difference is that feshwater lochs contain fresh water while seawater lochs contain seawater.
Answer 1) At the Surface. Answer 2) I disagree with the above answer. For practical purposes water is not compressible. Therefore the density is the same all over. The difference in density at the surface and at the bottom is so small that it is negligible. However, fresh water is less dense than seawater, since the salts dissolved in the seawater makes it more dense. For that reason, if you consider seawater near the mouth of a river, that water will be less dense than the seawater in general.
Seawater because it contains salt which makes the water more dense than water which does not contain salt.