A common feature of Baltic Sea organisms is the fact that their diversity is rather unexplored with respect to potential for biotechnological applications. As a brackish water body, one that is more saline than freshwater but less than seawater, the Baltic Sea comprises a diverse combination of freshwater and marine groups of microorganisms, with indigenous populations that have adapted to these unique conditions. According to census estimates, the Baltic Sea hosts at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, 1,199 zooplankton, 569 meiozoobenthos, 1,476 macroozoobenthos, 380 invertebrate parasites, about 200 fish, 3 seal and 83 bird species.