Currently taxonomists divide the mysticetes into the following four families although recently the fact that the Gray Whale stands alone in the family Eschrichtiidae has been challenged. * Balaenopteridae - Rorquals * Eschrichtiidae - Gray Whale * Balaenidae - Right Whales * Neobalaenidae - Pygmy Right Whale The suborder Odontoceti, the largest within the order Cetacea, comprises the toothed whales, which includes all dolphins and porpoises. Between them, the ten families contain 36 genera and 70 species, which include Sperm Whales, White Whales, the little known Beaked Whales and Pilot and Killer Whales. The largest Odontocete or toothed whale is the Sperm Whale reaching lengths of 20 metres. An animal of great extremes the Sperm Whale has the largest brain of any animal and probably makes the deepest dive of any whale, possibly up to 3000 metres deep that may last up to two hours in duration. The Sperm Whale is truly global in its coverage and may be found in all oceans of the world. * Physeteridae - Sperm Whales * Kogiidae - Dwarf and Pygmy Sperm Whales * Monodontidae - White Whales and Narwhal * Ziphiidae - Beaked Whales and Bottlenose Whales * Delphinidae - Dolphins, Humpbacked Dolphins, Pilot & Killer Whales * Plantanistidae, Iniidae, Lipotidae, Pontoporiidae - River Dolphins * Phocoenidae - Porpoises
