The baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea. Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans, the toothed whales or Odontoceti. Living species of Mysticeti have teeth only during the embryonal phase. Fossil Mysticeti had teeth before baleen evolved. The suborder contains four extant families and 15 species.