THE BLUE WHALE
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Balaenopteridae
Genus: Balaenoptera
Species: B. musculus
(Linnaeus,
1758)
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Also known as Antarctic blue whale, great Northern
rorqual, North Atlantic blue whale, North pacific blue whale, Sibbald’s
rorqual, Sulphur bottom whale.
·
The blue whale is the largest animal to have ever lived, being almost
as big as a Boeing 737 and even larger than the biggest dinosaurs. The largest
recorded length for a blue whale is 33.5meters, though most individuals vary
between 24 and 27m.
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The heart of this monstrous whale is actually around the size of a
Volkswagen beetle weighing as much as 900kg with blood vessels so broad that a
full-gown trout could swim through them.
·
It has a long tapered and streamlined body with the tail making up less
than 1/4th of its total body length. The body is smooth and
relatively free of parasites, although few may attach to the edge of the tail
fluke, the tip of the flippers and to the small triangular dorsal fin.
·
There is a row of 300 to 400 black baleen plates on each side of the
mouth and about 90 throat grooves that extends to the navel and allows the
throat to expand enormously during feeding.
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Despite its common name, the blue whale is actually grayish-blue, with
a mottled effect visible in some lights and can allow individuals to be
identified. The underside often possess a yellowish tinge, especially on whales
living in polar waters which is caused by the microscopic algae called
‘diatoms’ and led early whalers to nickname the animal as sulphur bottom whale.
·
They are often alone or in groups of two or three, but occasionally
large group of up to 60 may form in areas of high food abundance. It feeds
mainly on shrimp-like krill which are filtered through the baleen plates.
During feeding, large volume of water and food can be taken into the mouth and
as the mouth closes, water is expelled though the plates which trap the food
inside to be swallowed.
·
The blue whale reaches sexual maturity at 7 to 10 years of age, when it
will mate with several partners during winter and early spring. A single calf
is produced after a gestation period of 10-11 months and weaned at the summer
feeding grounds when it is about 7 months old.
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It inhabits the open ocean frequently along the continental shelf edge
and near polar ice. It feeds at both the surface and at depth, undertaking
diurnal vertical migrations as it follows its krill prey to depths of a least
100meters.
·
The blue whale is classified as endangered on the IUCN (International
Union for Conservation of Nature) red list. Although commercial whaling of the
blue whale is now banned (since 1966), its population is so small that any
further mortalities may seriously impact on the survival of the species. It is
still subject to a number of threats including ship strikes, noise and chemical
pollution and net entanglement.
Compiled and edited by
Jemimah
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