Blue Whale

Scientific Classification

Common Name

blue whale, sulpher-bottom

Kingdom

Animalia

Phylum

Chordata

Class

Mammalia

Order

Cetacea; more recently Cetartiodactyla

Suborder

Mysticeti

Family

Balaenopteridae

Genus Species

Balaenoptera musculus

Fast Facts

Description

Blue whales, named for their bluish-gray coloration, are known for their immense size. Their coloration often includes grayish or whitish areas. When viewed from above, the rostrum appears broad and U-shaped and a large splashguard surrounds two blowholes. A blue whale's slender, vertical blow can reach a height of 9 m (30 ft.). Blue whales have 55 to 68 vertical grooves extending back almost to the navel. The dorsal fin is very small and set ¾ of the way back and the trailing edge of the flukes are smooth except for a small notch in the center.
Female:  Females tend to be slightly larger than males

Size

For adults, a maximum of 33.5 m (110 ft.), but lengths of 21 m (70 ft.) are more common. Blue whale calves measure about 7 m (23 ft.) in length.
Male: For Antarctic adults at physical maturity, lengths of 25 m (82 ft.) are common; specimens from the Northern hemisphere are typically smaller
Female: For Antarctic adults at physical maturity, lengths of 27 m (88.6 ft.) are common; specimens from the Northern hemisphere are typically smaller; females tend to be slightly larger than males.

Weight

Long ago, Antarctic blue whales weighed 145,280 kg (320,000 lbs.). Newborn calves weigh 2,700 to 3,600 kg (6,000 to 8,000 lbs.).

Diet

Blue whales feed almost exclusively on euphausiid crustaceans (krill), with a variety of species being taken by different blue whale populations. They feed both at the surface and also at depth, following the diurnal vertical migrations of their prey to at least 100 m.

Incubation

12 months

Nursing Duration

Calves are weaned at eight months, when they gain as much as 90 kg (200 lbs.) a day

Sexual Maturity

At about 6 to 10 years of age

Life Span

At least up to 30 years, possibly to well over 40 years

Range

The blue whale is a cosmopolitan species, found in all oceans except the Arctic, but absent from some regional seas such as the Mediterranean, Okhotsk and Bering seas.

Habitat

Primarily found along the edges of continental shelves and sea ice. Some populations appear to be resident year-round in habitats of year-round high productivity, while others undertake long migrations to high-latitude.

Population

Global: the global population of blue whales is plausibly in the range 10,000–25,000. The population is severely fragmented but does appear to be increasing

Status 

IUCN: Endangered
CITES: Appendix I
USFWS: Endangered

Fun Facts

1. Blue whales belong to the cetacean suborder Mysticeti, the baleen whales. Whales in this suborder lack teeth. Instead, they have stiff, hair-like baleen plates that hang from their upper jaws. With the baleen plates, blue whales filter vast quantities of krill (tiny shrimp-like crustaceans), consuming as much as four tons per day.
2. Blue whales typically travel either singly or in pairs, although sometimes more whales may be found within close range in areas high in krill concentrations.
3. Blue whales are capable of producing low-frequency sounds, which can travel hundreds of miles in deep water. The function of these long-ranging vocalizations is not quite known although it is theorized that some of the vocalizations aid in navigation by imaging seamounts, islands and other underwater formations.
4. The blue whale is the largest animal in the world, probably the largest that ever lived. Long ago, Antarctic blue whales measured 30.5 m (100 ft.) and weighed 145,280 kg (320,000 lbs.). Whale hunters took the most massive whales, the biggest blue whales today measure about 26 m (85 ft.), but lengths of 21 m (70 ft.) are more common. A blue whale's heart alone may weigh 908 kg (2,000 lbs.), as much as a small car.
5. For more information about baleen whales, explore the Baleen Whales Info Book.

Ecology and Conservation

Widespread commercial whaling during the 19th and 20th centuries, severely depleted blue whale populations. The current worldwide population is a fraction of the more than 200,000 blue whales that once roamed the seas.

Several U.S. and international treaties and agencies including the International Whaling Commission, the U.S. Marine Mammal Protection Act of 1972 and the U.S. Endangered Species Act of 1973 protect blue whales. But despite more than 50 years of protection, blue whale populations have not recovered.

The Blue Whale was first listed as endangered in 1986.  The Antarctic blue whale (B. m. intermedia) subspecies should be listed separately as Critically Endangered due to a population reduction of over 97%.

The International Whaling Commission had granted protection to blue whales by 1966. They are protected by national regulations in many range states. Local measures may be required to protect the habitat of specific local populations in order to ensure their long-term viability in the face of increasing human impacts.

Bibliography

Jefferson, T.J. Leatherwood, S. and M.A. Webber. FAO Species Identification Guide. Marine Mammals of the World. Rome. FAO, 1993.

Leatherwood, Stephen, and Reeves, Randall R. The Sierra Club Handbook of Whales and Dolphins. San Francisco: Sierra Club Books, 1983.

Nowak, Ronald M. (ed.). Walker's Mammals of the World. Vol. II. Baltimore: Johns Hopkins University Press, 1991.

Parker, S. (ed.). Grizmek's Encyclopedia of Mammals. Vol. IV. New York: McGraw-Hill Publishing Co., 1990.

Reeves, R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell (Peter Folkens illustrator). National Audubon Society: Guide to Marine Mammals of the World. New York: Random House, 2002.

http://animaldiversity.ummz.umich.edu