Whales, dolphins, and porpoises are Cetaceans. The word cetacean comes from the Latin word cetus, which means "a large sea animal," and the Greek word ketos, which means "sea monster".There are currently 86 recognized species of whales, dolphins, and porpoises. Of these, 72 are Odontocetes, or toothed whales. Whales are classified into two major groups, those whales that have baleen plates in their mouths and those whales that have teeth in their mouths. Baleen whales also have two blowholes while toothed whales have one blowhole. There are 14 different species of baleen whales, with the largest being the blue whale. There are 72 species of toothed whales which includes all dolphins and porpoises, with the largest being the sperm whale.