Complex sentence: They include the various marine mammals, who dwell in oceans, as well as various river-dwelling species, such as the Platypus, the European Otter, all species of manatee save the West Indian manatee and the Amazon River Dolphin.
Split into simpler sentences: They include the various marine mammals, who dwell in oceans, as well as various freshwater species, such as the Platypus, the European Otter. The classification all species of manatee save the West Indian manatee and the Amazon River Dolphin.