Fauna of Europe of the Baltic Sea has led to the evolution of many slightly divergent species, such as the Baltic Sea herring, which is a smaller variant of the Atlantic herring. The most frequent benthic species are "Saduria entomon" and "Monoporeia affinis", which is originally a freshwater species. A great part of its bottom is anoxic and without animal life. The Baltic Sea and North Sea are also home to a variety of marine mammals (common seals, grey seals). Europe contains several important freshwater ecoregions, including the heavily developed rivers of Europe, the rivers of Russia, which flow into the Arctic, Baltic,
Ports of the Baltic Sea Ports of the Baltic Sea There are over 200 ports in the Baltic Sea. When only those ports that handle a minimum of 50,000 tonnes of cargo annually, and where at least part of this cargo is international are taken into account, the number of ports reaches approximately 190. In 2008, the total amount of cargo handled in the Baltic Sea ports amounted to 822.4 million tonnes, which was 0.4 per cent less than in 2007. Primorsk, Saint Petersburg and Muuga were the biggest ports in the Baltic Sea in 2008. Together the three top ports handled over one fifth