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The blue whale is the largest animal ever known to have existed.
During the 20th century, the species was almost exterminated due to commercial whaling.
From conception to weaning, it represents a several billion-fold increase in tissue in just over a year and a half.
Life Cycle At birth, a blue whale calf is the largest baby on earth: approximately 8m long and weighing about 4 tonnes.
They grow at a rate of 90 kg per day and wean after 7-8 months, once they have reached about 15 m in length, and are able to follow the normal migration pattern alone. This growth rate is astonishing and is probably the fastest in the animal kingdom.
The largest ever recorded was a gargantuan 33.5 m long. The blue whale's heart is the size of a small car and its beat can be detected two miles away. Blue whales are the loudest animals on earth and their calls are louder than a jet engine: reaching 188 decibels, while a jet's engine hit 'just' 140 decibels.
Apart from their gigantic size, blue whales can be identified by their relatively small dorsal fin, a fairly rounded rostrum (anterior part of the skull), and approximately 90 ventral grooves, which reach the navel.
However, the blue whale has the most powerful voice in the animal kingdom and its low-frequency sounds can travel in deep water over hundreds, or even thousands, of miles.
Under these circumstances, animals which may appear to us to be traveling alone may actually be in constant contact with one another.
The species has slowly recovered following the global whaling ban but it remains endangered and faces a number of serious threats including ship strikes and the impact of climate change.
Blue whales are simply enormous with most ranging in length from 24-30 m. Just to put that in perspective: an adult male African elephant weighs 6 tonnes!
Blue whales mostly travel alone or in groups of 2-3.
Larger groups of up to 60 whales have been reported and are probably associated with feeding grounds.