The family Balaenopteridae contains the six species of rorqual whales such as the Blue Whale, Humpback Whale and other similarly shaped whales. The family Eschrichtiidae is represented by one modern species, the Grey Whale. The family Balaenidae once included all four species of Right Whales and this is still recognised by many people. The Monodontidae family is represented by three species, the Narwhal, the Beluga and the Irrawaddy Dolphin. There are six species of Pilot and Killer Whales in the Globicephalidae family.
Some taxonomists classify only two species though.
The Phocoenidae family is represented by the six species of porpoise. Many people confuse dolphins and porpoises, often due to the American custom of calling dolphins porpoises. Porpoises do belong in their own family and are quite different to a dolphin. The final family in the suborder Odontoceti is the Platanistidae family, including five species of river dolphins. They are generally regarded as separate species though.