Density and Temperature

This picture perfectly shows the affect temperature has on density. The red water is colder, thus more dense. Because the Red water is more dense, the hot, clear water on top of it will not mix with it.If the two jars were reversed, the cold water would seep down into the hot water and mix. This helps my understanding of the aquatic ecosystem because knowing  the fact that hot water stays on top helps me understand why fish live in the places they do.