Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 26. Chapters: 52-Hertz whale, Beached whale, Exploding whale, Husavik Whale Museum, Melon (whale), Tay Whale, Whale fall, Whale sounding, Whale sounds, Whale surfacing behaviour, Whale watching. Excerpt: Whale (origin Old English hwael from Proto-Germanic *hwalaz) is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to the suborder Odontoceti (toothed whales). This suborder also includes the sperm whale, killer whale, pilot whale, and beluga whale. The other Cetacean suborder, Mysticeti (baleen whales), comprises filter feeders that eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the blue whale, the humpback whale, the bowhead whale and the minke whale. All cetaceans have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings (blowholes) on top of the head. Whales range in size from the blue whale, the largest animal known to have ever existed at 30 m (98 ft) and 180 tonnes (180 long tons; 200 short tons), to various pygmy species, such as the pygmy sperm whale at 3.5 m (11 ft). Whales collectively inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3% to 13%. Cetaceans are divided into two suborders: Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla, which includes both whales and hippopotamuses. Whales are the hippopotamus's closest living relatives. Ambulocetus natans - a primitive cetacean All cetaceans, including whales, dolphins and porpoises, are descendants of land-dwelling mammals of the Artiodactyl order (even-toed ungulates). Both are related to the Indohyus, .