Baltic Sea as species in 2005 and 2018 respectively, having formerly been confused with more widespread relatives. The tiny Copenhagen cockle ("Parvicardium hauniense"), a rare mussel, is sometimes considered endemic, but has now been recorded in the Mediterranean. However, some consider non-Baltic records to be misidentifications of juvenile lagoon cockles ("Cerastoderma glaucum"). Several widespread marine species have distinctive subpopulations in the Baltic Sea adapted to the low salinity, such as the Baltic Sea forms of the Atlantic herring and lumpsucker, which are smaller than the widespread forms in the North Atlantic. A peculiar feature of the fauna is that it contains a
Baltic Sea such as minke whales, bottlenose dolphins, beluga whales, orcas, and beaked whales visit the waters. In recent years, very small, but with increasing rates, fin whales and humpback whales migrate into Baltic sea including mother and calf pair. Now extinct Atlantic grey whales (remains found from Gräsö along Bothnian Sea/southern Bothnian Gulf and Ystad) and eastern population of North Atlantic right whales that is facing functional extinction once migrated into Baltic Sea. Other notable megafauna include the basking sharks. Satellite images taken in July 2010 revealed a massive algal bloom covering in the Baltic Sea. The area of the bloom