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( Blue Whale)
The Blue Whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti).[3] At up to 33&_160;metres (110&_160;ft) in length and 181&_160;metric tonnes (200&_160;short tons) or more in weight, it is believed to be the largest animal ever to live.[4][5] Long and slender, the Blue Whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath.[6] There are at least three distinct subspecies B. m. musculus of the north Atlantic and north Pacific, B. m. intermedia, of the Southern Ocean and B. m. brevicauda (also known as the Pygmy Blue Whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists mainly of small crustaceans known as krill, as well as small fish and sometimes squid. Blue Whales were abundant in nearly all oceans until the beginning of the twentieth century. For over 40 years they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide[7] located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate.[8] Before whaling the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000).[9] There remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic and at least two in the Southern Hemisphere. Blue Whales are rorquals (family Balaenopteridae), a family that includes the Humpback Whale, the Fin Whale, Bryde's Whale, the Sei Whale and the Minke Whale.[3] The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene. However, it is not known when the members of those families diverged from each other. The Blue Whale is usually classified as one of seven species of whale in the genus Balaenoptera; one authority placed it in a separate monotypic genus Sibbaldus,[10] but this was not accepted elsewhere.[1] DNA sequencing analysis indicates that Blue Whales are phylogenetically closer to the Humpback (Megaptera) and the Gray Whale (Eschrichtius) than to other Balaenoptera species. If further research confirms these relationships, it will be necessary to reclassify the rorquals.
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