The blue whale (
Balaenoptera musculus) is a marine mammal belonging to the baleen whales (
Mysticeti).[9] At 30 metres (98 ft)[10] in length and 190 tonnes (210 short tons)[11] or more in weight, it is the largest existing animal and the heaviest that has ever existed.[12]
Long and slender, the blue whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath.[13] 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 almost exclusively of small crustaceans known as krill.[14]
Blue whales were abundant in nearly all the oceans on
Earth until the beginning of the twentieth century. For over a century, 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,[15] located in at least five groups. More recent research into the
Pygmy subspecies suggests this may be an underestimate.[16] Before whaling, the largest population was in the
Antarctic, numbering approximately 239,000 (range 202,000 to
311,000).[17] There remain only much smaller (around 2,000) concentrations in each of the eastern North Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic, and at least two in the
Southern Hemisphere.
As of 2014, the
Californian blue whale population has rebounded to nearly its pre-hunting populationBlue 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.[9] The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene (28 Ma ago). It is not known when the members of those families diverged from each other.
The blue whale is usually classified as one of eight species in the genus Balaenoptera; one authority places it in a separate monotypic genus, Sibbaldus,[19] but this is not accepted elsewhere.[1]
DNA sequencing analysis indicates that the blue whale is phylogenetically closer to the sei whale (
Balaenoptera borealis) and Bryde's whale (
Balaenoptera brydei) than to other Balaenoptera species, and closer to the humpback whale (
Megaptera) and the gray whale (
Eschrichtius) than to the minke whales (
Balaenoptera acutorostrata and
Balaenoptera bonaerensis).[20][21] If further research confirms these relationships, it will be necessary to reclassify the rorquals.
There have been at least 11 documented cases of blue/fin hybrid adults in the wild. Arnason and Gullberg describe the genetic distance between a blue and a fin as about the same as that between a human and a gorilla
.[22] Researchers working off
Fiji believe they photographed a hybrid humpback/blue whale[23] including the case of discovery thorough
DNA analyzing from a meat sample found on
Japanese market.[24][25]
The first published description of the blue whale comes from
Robert Sibbald's Phalainologia
Nova (1694).
In September 1692,
Sibbald found a blue whale that had stranded in the
Firth of Forth—a male 24 m (78 ft)-long—which had "black, horny plates" and "two large apertures approaching a pyramid in shapeThe first published description of the blue whale comes from Robert Sibbald's Phalainologia Nova (1694). In September 1692, Sibbald found a blue whale that had stranded in the Firth of Forth—a male 24 m (78 ft)-long—which had "black, horny plates" and "two large apertures approaching a pyramid in shape".[26]
The specific name musculus is
Latin and could mean "muscle", but it can also be interpreted as "little mouse".[27]
Carl Linnaeus, who named the species in his seminal
Systema Naturae of 1758,[28] would have known this and may have intended the ironic double meaning.[29]
Herman Melville called this species sulphur-bottom in his novel Moby-Dick due to an orange-brown or yellow tinge on the underparts from diatom films on the skin. Other common names for the blue whale have included
Sibbald's rorqual (after Sibbald, who first described the species), the great blue whale and the great northern rorqual. These names have now fallen into disuse.
- published: 02 Feb 2015
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