Vanishing Species - The Blue Whale

An article by Mohan Pai

The Blue Whale

Balaenoptera musculus


Critically endangered Blue Whale is the largest animal to have ever lived, almost as big as Boeing 737 and even larger than the biggest dinosaurs.

With lengths up to 100 feet (30 m) and weights up to 150 tons (136 metric tons), the blue whale is the largest animal that ever lived on this planet. An average individual is 70 feet (21 m) long and weighs 100 tons (90 metric tons). The female, which is larger than the male, gives birth to a calf that averages 25 feet in length and weighs about 2 tons. The calf drinks about 106 gallons of milk every day. An average adult has almost 2,500 gallons of blood and burns up to 3 million calories a day. Its heart weighs more than a ton and the tongue alone weighs about 2 tons! Linnaeus must have had his tongue in his cheek when he gave this species the Latin name "musculus," which means "little mouse."As the common name indicates, the upper parts of the body are mottled blue-gray. The undersides are whitish or light yellow. This whale has a relatively small dorsal fin and black baleen plates. The straight, column-like water spout can reach 20 feet into the air. Speeds of up to 23 miles per hour (20 knots) have been recorded for the blue whale.

For many, many years ancient sailors had rare encounters with these gigantic ocean mammals and were terrified by their overwhelming size and powerful tails. You can understand a little of the fear and trepidation they might have felt upon seeing these huge, mysterious creatures for the first time. Today we know them to be virtually harmless to humans and that they have quite a bit in common with us – they, too are warm-blooded mammals that must breathe air. They are highly social animals with complex languages and intelligence. Most importantly, they are not monsters at all, but gentle giants we have come to respect, admire and protect.

Size comparison against an average human

Diet

Blue whales diet consists mainly of krill, a tiny shrimp that lives in tremendously large schools in almost every ocean of the world. Krill is probably one of the most plentiful food species (outside of insects) anywhere on earth. It's got to keep up with the blue whale's big appetite. A big blue can eat over a thousand krill at one time swallowing them with a tongue that weighs as much as an elephant! Blue whales eat the krill using a special type of filter on their mouths called a baleen. By gulping enormous amounts of sea water containing the live krill the blue whale closes its mouth and flushes the sea water back out through the filter leaving the krill behind for it to swallow. Small fish and plankton are also favorite food items of the whale. It takes about 8,000 lbs/3600kg of fresh seafood a day to keep the blue whale well fed.

Vocalisation

Probably the most spectacular thing about blue whales that's bigger than big is the sounds they make. Scientists have measured the low-frequency (deep rumbling) sounds they make when they communicate with each other by using a decibel meter. Some of their vocalisations have been recorded as loud as 188 decibels and can be heard as far as 530 mi/848km away. To give you an idea of just how loud 188 decibels is a commercial jet taking off makes a sound of 120 decibels. That makes whales, by far, the loudest living thing anywhere on earth!

Range

Found in the Atlantic, Pacific, Arctic and Indian Oceans, with a range that extends from the periphery of drift-ice in polar seas to the tropics . Three main populations persist: one in the southern hemisphere, one in the North Pacific and one in the North Atlantic ).

In India, the Blue Whales have been washed ashore in Karnataka, Maharashtra, Gujarat, Tamil Nadu, Kerala and Andhra Pradesh.

Red area indicates the range of the Blue Whale

Life History

Blue whales migrate several thousand miles to wintering grounds and fast for the duration of their stay; the fat on their body is enough to see them through the whole winter. The mating season occurs for 5 months over the winter. A single calf is born after a gestation period of one year. It nurses for 7 months and will reach sexual maturity at 5-15 years of age. Females give birth every 2-3 years.

Status

The blue whale is currently one of the world's most endangered whales. It was not hunted until somewhat modern techniques made them more easily attainable.

Blue Whales were abundant in nearly all the oceans until the beginning of the twentieth century. For over 40 years, they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide, located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate. Before whaling, the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000). There remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic, and at least two in the Southern Hemisphere.

Blue Whale skeleton, outside the Long Marine Laboratory at the University of California, Santa Cruz

Major Threats

The main threat in the past was direct exploitation, which only became possible in the modern era using deck-mounted harpoon cannons. Blue whale hunting started in the North Atlantic in 1868 and spread to other regions around 1900 after the northeastern Atlantic populations had been severely reduced. The Antarctic and North Atlantic populations were probably depleted to the low hundreds by the time whaling ceased, but are increasing . Blue whales have been protected worldwide since 1966, although they continued to be caught illegally by former USSR fleets until 1972. The last recorded deliberate catches were off Spain in 1978.

References: Dept. Of Environmental Conservation, New York State, Wikipedia, IUCN Red List.

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