BLUE WHALE
| Blue whale a baleen whale, Balenoptera muscula. Also called the
sulfur-bottom whale and Sibbald's rorqual, it is the largest animal
that has ever lived. Blue whales have been known to reach a length
of 100 ft (30.5 m) and to weigh as much as 120 tons; however, specimens
even 80 ft (24.4 m) long are now very rare because of extensive
whaling. B. muscula is slate blue in color and has a dorsal fin. It
is toothless, and has fringed baleen, or whalebone, plates in its mouth,
which act as a food strainer. As water is expelled from the whale's mouth,
plankton is trapped behind the strainer. The neck of the blue whale has
80 to 100 conspicuous furrows called ventral grooves, which alternately
expand and contract as the animal takes in and expels water. The blue whale
is cosmopolitan in distribution. In summer it inhabits polar seas, feeding
in the water of melting icepacks; in winter it migrates to warmer latitudes,
occasionally reaching the equator. Mating occurs at the end of winter,
with a single calf born every second or third year, after a gestation period
of 10 to 11 months. The calf is nursed for 6 months, and reaches puberty
in about 3 yr. Blue whales may live as long as 50 yr. They are classified
in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Cetacea,
family Balaenopteridae. See G. C. Small, The Blue Whale (1971).
________________________________________ The 1998 Canadian & World Encyclopedia Copyright © 1997 by McClelland & Stewart Inc. |