<span>I think for the most part, the warmth of the waters determine what lives in them. In warmer coastal waters, you are going to find coral reefs that provide homes to millions of species of fish and micro-organisms.</span>
In the atmosphere, the density of air particles decreases with height, with more gas particles remaining near the surface of Earth. When only taking into account humidity, dry air is more dense than moist air because of molecular weights of the gases.
The troposphere has the highest density.