It is every drop of waterís dream to live at sea level. Water
precipitates on land and travels to sea through rivers. The rivers erode
the land and chemically dissolves the components of rocks into ions.
Over eons of time, most elements become dissolved in seawater. These
ions help give the "flavor" to salt water.
Many of these ions can be combined into molecules that are used by
living organisms. For example, little critters (protist) like
foraminifers require CaCO3 (calcium carbonate) to make
skeletons. Radiolaria another protozoa require SiO3 (silica
dioxide) to make their skeleton. Other components can be dissolved in
marine water while maintaining their own properties. Gases, like oxygen,
are very important to help large organisms like fish survive. Small
plants on the oceanís surface contribute the majority of oxygen in the
water and the atmosphere.
The oceans become the largest holder of water. However, most land
animals cannot use salt water directly. The only parts of the oceans
that can be used as "fresh" water are icebergs. Only pure
water can freeze, leaving behind the salt.