It is indeed true that only the water of marine ecosystems contains dissolved salt. Marine ecosystems, also known as salt water ecosystems, are aquatic ecosystems that waters harbor a substantial volume of dissolved salts. Definite features of individual salt water ecosystems differ significantly, however knowing their total basic surfaces gives an extensive image of their role, value and function. Furthermore, there are so many types of salt water ecosystem, the open ocean is not the only one. Other types include tidal zones, shorelines, estuaries, mangroves, coral reefs, salt marshes and swamps, hydrothermal vents and the ocean floor, just to name a few of the more main groups.