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The blue whale (Balaenoptera musculus) can be about 30 meters long, weigh more than 150 tons, and is the largest animal that has ever lived on earth, as far as we know. The heart is as big as a car.
It feeds mainly on krill (small crustaceans), which it captures by filtering large amounts of water through comb-shaped bards in its mouth.
The number of blue whales was estimated at the beginning of the 20th century at around 400,000. Due to intensive hunting, the number dropped to less than 10,000 around 1950, after which the blue whale was protected in 1966. Today, the number is estimated to be between 10,000 and 25,000 individuals.
Blue whales are found in all major seas except the Arctic. However, it is very rare, since it habitually lives offshore and because the number of specimens remains low.
The sound of the blue whale can amount to 188 dB, which is significantly louder than a jet engine. However, the frequency is so low that the human ear cannot perceive it as sound; 17-20 Hz. Therefore, special instruments are required to record the song of choice.
Source: International Whaling Commission (iwc.int)
