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,
Pacific barracuda however, when young, Pacific barracuda are found in bays in shallow waters. However, some Pacific Barracuda have been recorded to be found in deep waters, about 37 m. The Barracuda are known to form schools and move across the ocean in these schools of fish. However, in some larger species, it has been noted that they can be found swimming solitarily. The Pacific barracuda are a predatory fish, exhibiting aggressive behavior in order to feed on other small fishes. Their diet primarily consists of small fish such as anchovies, small pacific mackerels, grunions, squid, groupers, grunts, and even young barracuda.