They belong to the order Cetacea, which is further divided into two suborders:
* Odontocetes: toothed whales, such as dolphins, porpoises, and killer whales.
* Mysticetes: baleen whales, such as humpback whales, blue whales, and right whales.
So, while whales are a distinct group within mammals, they are still part of the broader class of mammals.