|
Blue Whales The Blue whale is the largest creature of the sea; in fact, it’s
the largest creature known to man. Contrary to what most people think, even
though Blue whales live in the sea, they are mammals. They breathe air, have
their babies born alive, and can live anywhere from 30 to 70 years. The Blue
whale is a baleen whale, and instead of having teeth, Blue whales have around
300-400 baleen plates in their mouths. Baleen are rows of coarse, bristle-like
fibers used to strain plankton from the water. Baleen is made of keratin, the
same material as our fingernails.
The Blue whale is called a “rorqual”, a Norwegian word for “furrow” referring
to the pleated grooves running from its chin to its naval. The pleated throat
grooves allow the Blue whale’s throat to expand during the huge intake of water
during filter feeding; they can “hold 1,000 tons or more of food and water when
fully expanded” (Small 1971).
They average about 50-70 throat grooves. Blue whales grow up to about 80 feet
(25m) long on average, weighing about 120 tons. The females are generally larger
than the males, this is the case for all baleen whales. “The largest specimen
found was a female 94 feet (29m) long weighing more than 174 tons” (Satchell
1998). The head of the Blue whale forms up to a quarter of the total body
length.
Compared with other rorquals, the head is very broad. The blue whale heart is
also large, the size of a small car and can pump almost 10 tons of blood
throughout the body. They also have a very small, falcate (sickle-shaped) dorsal
fin that is located near the fluke, or tail. Blue whales have long, thin
flippers 8 feet (2.4m) long and flukes that are 25feet (7.6m) wide.
The blue whale’s skin is usually blue-gray with white-gray spots. The
underbelly has brown, yellow, or gray specks. During the winter, in cold waters,
diatoms stick to the underbelly, giving it a yellow to silver- to sulfur-colored
sheen; giving the blue whale its nick-name of “sulfur bottoms”. Other names
include Sibbald’s Rorqual and Great Northern Rorqual. Blue whales (like all
baleen whales) are seasonal feeders and carnivores that filter feed tiny
crustaceans (krill, copepods, etc), plankton, and small fish from the water.
Krill, or shrimp-like euphasiids are no longer than 3 inches.
It is amazing that the world’s largest animals feed on the smallest marine
life. Blue whales are gulpers, filter feeders that alternatively swim, then gulp
a mouthful of plankton or fish. “An average-sized blue whale will eat
2,000-9,000 pounds (900- 4100kg) of plankton each day during the summer feeding
season in cold, arctic waters (120 days)” (Hasley 1984). The blue whale has twin
blowholes with exceptionally large fleshy splashguards to the front and sides.
It has about 320 pairs of black baleen plates with dark gray bristles in the
blue whale’s jaws.
|
