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Blue Whale Balaenoptera musculus


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Blue Whale
credit: NOAA

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Family: Balaenopteridae, Rorquals view all from this family

Description The world’s largest animal, and the largest animal ever to exist, they are mottled blue with a U-shaped head and tiny dorsal fin. Larger than Fin Whale, with a blue mottled back (not smooth gray), a more rounded head, and a less prominent dorsal fin. Shape of dorsal fin varies from round to pointed. Belly may be light blue, white, or yellow. Long slender flippers tipped in white. Thick, smooth tail stock. Females are larger than males, and may weigh as much as 30-40 African elephants. Animals are larger in the southern hemisphere. High, slender blow.

Dimensions 22-28m, 64,000-195,000kg

Endangered Status The Blue Whale is on the U.S. Endangered Species List. It is classified as endangered in the states its range reaches, California and Massachusetts. Whalers in the 19th and 20th centuries hunted this giant nearly to extinction, killing 29,000 in 1931, probably the peak year. Since coming under the protection of the International Whaling Commission in 1965, the Blue Whale has shown encouraging signs of recovery. Its numbers do not approach what they were before its exploitation, but they have been on the increase in the North Pacific and North Atlantic Oceans. Whereas there were once probably 200,000 Blue Whales in Earth's oceans, today there may be about 5,000.

Breeding Mating and calving must occur well offshore. Calves are 6-7m at birth in fall and winter, and they nurse for 7-8 months to reach 16m. The nursing young put on 90kg per day. Sexual maturity is reached at about 5 years, when the animals are about 20m long.

Habitat Offshore waters

Range New England, Mid-Atlantic, Florida, Texas, California, Northwest, Eastern Canada, Western Canada, Alaska

Discussion A rare and Endangered species. Migrates along both coasts between summer Arctic waters and winter southern waters.