- Education and Science»
- Life Sciences
Blue Whale: Getting To Know The Largest Animal On Earth
Blue Whale, Balaenoptera musculus, is not only the largest mammal but also the largest animal that walks, rather swims, on Earth today. They belong to the group 'rorqual whales'; the whales that have pleats on their throat.
It's larger than one of the largest dinosaur ever walked on Earth, Argentinosaurus, and equal to 25 African elephants, which is the third largest animal on Earth today.
Speaking of size, their tongue itself can weigh as much as a single elephant, and heart up to a family car!
Their classification goes like this:
- Kingdom- Animalia
- Phylum- Chordata
- Class- Mammalia
- Order- Cetacea
- Suborder- Mysticeti
- Family- Balaenopteridae
- Genus- Balaenoptera
- Species- musculus
Characteristics Of Blue Whale
Despite having 'blue' associated with its name, a blue whale is actually not blue in colour, instead, they are mottled blue-grey. However, they appear true blue under water.
They provide an excellent home to several microorganisms like diatoms, algae, phytoplankton etc, which imparts yellow to orange-brown colour on their bottom part. They tend to attach and grow on their skin.
The 'blue' colour of the whale was first studied by a Scottish naturalist, Robert Sibbald in 1694 and therefore, they are also known as 'Sibbald's Rorqual'. They are also called 'Sulfur Bottom Whale' due to the yellowish colour of its bottom-belly.
The blue whale has a flat, U-shaped and broad head with a long and tapering body. Their body ends with a long, triangular tail, which is called flukes.
The average width of a blue whale fluke is about 25 fts (7.6 m).
All the cetacean's head consists of a hole called a blowhole, which it uses to breathe air. A blowhole is homologous to mammalian nostrils. Blue whale exhales air, along with mucus and nitrogen from its metabolism through the blowhole when it reaches to the surface in the form of a spray called the blow. The blow from the blowhole can reach up to 30 ft (9 m) in the air.
The average length of this largest mammal is about 98fts, with an average weight of 170-190 tons. Females are larger in all the rorqual whales, in general.
The heaviest blue whale, as per records was 210 tons and the longest blue whale was a female with 33.6m (110fts)!
On an average, the blue whales found in Pacific and North Atlantic oceans are smaller than those from the sub-Antarctic ocean.
They have pleats on their throat. These pleats help them to expand the area of the throat to take in a huge gulp of food-laden water.
They have a small falcate dorsal fin which is located near the tail. Their flippers are long but thin, about 8 fts (2.4 m) in length.
Their body circulates about 10 tons of blood each time their heart pumps to complete the need of such a huge body!
Blue whales are usually a solitary creature but sometimes they move in small groups or in pairs. They usually spend their summers in the poles and winters in the equator regions.
Their casual speed is about 5 miles per hour but they can move as fast as 20 miles per hour when needed, despite their huge body!
Irrespective of the fact that it has a huge, huge body, Blue Whales eat only krill and sometimes other small fishes. An adult Blue Whale eats about 4 tons of krill each day!
They open wide their mouth, expanding the throat using the pleats- taking in a huge amount of water with food. The whale then expels out the water through the thin baleen plates using its tongue.
There are three subspecies of blue whales-
- the pygmy blue whale, Balaenoptera musculus brevicauda, which is found in the Southern Hemisphere and Northern Indian Oceans. These are the shortest ones with length about 24 m but have a larger head than others. Their body is torpedo-shaped and hence these can be easily distinguished from other whales.
- Balaenoptera musculus musculus is another subspecies which is found in the Northern Hemisphere. These are about 23-27 m long.
- The third subspecies is Balaenoptera musculus intermedia which is the Antarctic Blue Whale with an average length of 29 m and longest recorded 33.6 m.
Reproduction And Motherhood
Blue whale breed in the winter season. Their babies are called calf.
They give birth to calf like other mammals and unlike fishes who lay eggs. They usually give birth to one calf (rarely twins- 1% cases) in a duration of 2 years.
Calves are usually 25 fts long and 6-8 tons by weight when they are born! Being the future ruler of the sea they are, a blue whale calf can swim perfectly within minutes of their birth.
The 'mommy' Blue Whale feeds her calf with her milk like all the other mammals do. The newborn calf remains dependent on his mother's fatty milk for about 7-8 months and takes about 100 gallons of milk per day and gains about 200lbs each day!
The mother and baby live together for a year or so and then it's set off to live his life on his own. By this time the calve becomes about 45 ft or 13 m long.
Blue whales reaches maturity at 10-15 years.
Sounds Produced By Blue Whales
Now, this is one fascinating feature of Blue Whales.
They produce sounds to communicate with each other, which is a pulsating sounds, groans or moans.
Though Blue whales don't have external ears, but their bones and flesh carries the sound to the skull, where they "sense" the sound. As per reports, Blue Whale's sounds are more felt than heard.
These sounds are produced by the air-sacs present below the blowhole. These are filled with air, which when released produces sound.
They produce a low-pitched sounds which at the maximum recorded as 188 decibel. And it's the loudest sound produced by any animal!
As per scientists, blue whales not only communicate with each other using these sounds but also utilizes the same to check the light-less portions of the sea.
Amazingly, blue whales can hear the voices of another blue whale from a distance of 1000 miles!
Blue whales live a pretty long life. Their average lifespan is about 80-90 years. The maximum age of the whale, counted using the earwax like earplug layer of the whale, was about 110 years!
Blue Whale's Greatest Enemy!
It's sad to say that the number 1 enemy of these huge but beautiful creatures are "WE", the humans!
They've been hunted for meat and oil since 3000 B.C!
The group of people who hunt Blue Whale are called the "Whalers".
However during that era hunting whales was not as easy as it is now due to the lack of technology, after all hunting a creature of about 98 fts is not an easy task. Therefore, whales were still flourishing and stayed that way until the 20th century, when even more modern equipment for whaling were discovered.
Hunting Whales, called Whaling, took place at it's maximum in the period of 1930s. In 1931 alone, about 29,649 whales were killed! And as the years passed by, in 1930s some about 50,000 Blue Whales were killed every year!
The most common whales that are being killed are the Common Minke Whales and the Antarctic Minke Whale.
Problems In Recovering The Damage To The Whale Population
The obvious reason is the huge Whaling rate. An adult female gives birth to ONE calf in every two years. Since the rate of reproduction of Whale's is so slow, it's impossible to recover the damage when we compare the rate of reproduction with the rate of whaling.
As per the World Wildlife Fund for Nature, 90% of the North Pacific and Atlantic Whales are killed due to the human interference, i.e. collision with the boat, whaling and also in unintentional catchings
Step Took By International Whaling Commission (IWC)
Finally in 1966, whales were declared protected and they banned the commercial whaling. However, whaling is still in peak in countries like Japan; who say that they have enough stock to do limited hunting!
Between 10,000 t0 25,000 whales are still swimming freely in the large oceans. The huge whaling happened in the 1900s brought this beautiful creature on the line of extinction. Blue whales are now classified as endangered on the World Conservation Union (IUCN) Red List.
What We Can Do?
- We can spread our words by interacting with others.
- We should not buy Whale products; meat or oil.
- We should support various organizations like WWF to actively take action against the whalers.
Their future is in our hands. Take Action because if you'll not then nobody will!
Have you ever participated in animal conservation programs or campaigns?
© 2012 Sneha Sunny