Taxonomy/Description

Blue whales belong to the Mammalian Order Cetacea, in the suborder Mysticeti.  All baleen whales belong to the suborder Mysticeti, which is Latin for "mustached whales".  The blue whale belongs to the rorqual family, Balaenopteridae.  The word "rorqual" means "tube whale or furrowed whale", referring to the pleats on the lower jaws of rorquals.  All rorquals have baleen, a dorsal fin and throat grooves.  Other members of this family include the humpback whale, fin whale, and minke whale.  The blue whale's scientific name is Balaenoptera musculus.  Its generic name, Balaenoptera, means "winged whale", which refers to the blue whale's dorsal fin.  The blue whale's specific name, musculus, means "little mouse".  The blue whale is currently the largest extant animal.  Blue whales may exceed 100ft in length and 100 tons in weight.  Female blue whales are usually larger than males of the same age.  Blue whale's of the northern hemisphere are smaller in size than those of the southern hemisphere.

Habitat/Diet

Blue whales are found in all oceans.  Their major food sources, krill and euphausiids, live in all regions.  Temperate, tropical, and polar seas all supply the blue whale with its invertebrate prey.  The blue whale eats about four tons of krill per day during the summer feeding season.  That's about 40 million krill each day!  As the whale opens its large mouth to gulp up the krill, the pleats of its lower jaw expand to contain the large volume of water.  The whale then presses its tongue up against the roof of its mouth, straining the water through its 520-800 baleen plates.  These 20-40 inch plates are composed of keratin, the same substance of fingernails and hair.  The ends of baleen are brush-like, preventing the krill from escaping.  The krill remain inside, and are consequently swallowed.

Behavior/Reproduction

Blue whales migrate from cooler arctic waters to warmer temperate and tropical waters to calve and feed.  Calves are born at intervals of 2-3 years.  Gestation is about 12 months.  A single calf is born weighing three tons, with a length of 23-27 feet.  A blue whale calf drinks 100 gallons of milk daily.  From the fat rich milk it gains 200lbs and 1.5 inches in length each day.  The calf will nurse for 7-8 months, weaning when it reaches 52 feet.  Blues reach sexual maturity at 6-10 years.  Occasionally seen solitarily or in small pods, blue whales are usually observed in pairs.  Loose groups of 50 or more have also been sighted.

Conservation

Blue whales are so large that primitive whalers were unable to hunt them.  The paddle driven boats and hand harpoons were too small to bring down the enormous blue whale.  The use of steam powered boats, new whale inflation techniques, and the invention of the exploding harpoon gun by Norwegian whalers ended this animal's invulnerability.  One blue whale could yield 120 barrels of oil.  What was once a population of 350,000 individuals shrank by 95%.  The blue whale became so scarce that whalers began to hunt other cetacean species.  Only recently, under international protection, has the current blue whale population of 3,000-4,000 showed signs of recovery.

Photos courtesy Patty Geary, copyright © 2003, all rights reserved.