BLUEWHALE

The Blue whale:-
is a marine mammal belonging to the suborder of baleen whales (called Mysticeti).[3] At up to 33.59 metres (110 ft 2.5 in) in length and 181 metric tonnes tons)or more in weight, it is believed to be the largest animal ever to have existed.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.
Taxonomy:-
also: Evolution of cetaceans
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.


Feeding:-
Blue Whales feed almost exclusively on krill, though they also take small numbers of copepods.[24] The species of this zooplankton eaten by Blue Whales varies from ocean to ocean. In the North Atlantic Meganyctiphanes norvegica, Thysanoessa raschii, Thysanoessa inermis and Thysanoessa longicaudata are the usual food.[25][26][27] In the North Pacific Euphausia pacifica, Thysanoessa inermis, Thysanoessa longipes, Thysanoessa spinifera, Nyctiphanes symplex and Nematoscelis megalops;[28][29][30] in the Antarctic Euphausia superba, Euphausia crystallorophias and Euphausia valentin