Whale (origin Old English hwael) is the common name for any large marine mammal of the order Cetacea, which have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings on top of the head.  The term whale is sometimes used to refer to all cetaceans, but in more common usage it generally excludes those members of the Delphinoidea superfamily which are known as dolphins and porpoises.  These smaller species belong to the suborder Odontoceti (toothed whales), which also includes the sperm whale, killer whale, pilot whale, and beluga whale.
The suborder Mysticeti (baleen whales), are filter feeders that feed on small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder contains four families and fourteen species including the blue whale, the humpback whale the bowhead whale and the minke whales. Whales range in size from the blue whale, the largest animal known to have ever existed at 35 m (115 ft) and 150 tonnes (150 LT; 170 ST), to various pygmy species, such as the pygmy sperm whale at 3. m (11 ft). Whales collectively inhabit all the world’s oceans and number in the millions, with population growth rate estimates for various assessed species ranging from 3% to 13%.  For centuries, whales have been hunted for meat and as a source of raw materials. By the middle of the 20th century, however, industrial whaling had left many species seriously endangered, leading to the end of whaling in all but a few countries.