The largest animals ever to have lived on the planet (surpassing even dinosaurs), blue whales inspire awe and wonder with all the records they break: The largest blue whale ever recorded was 33 m long; a blue whale’s heart is the size of a small car; a child could crawl through a blue whale’s arteries; and blue whales produce the loudest sound on earth – even if it is too low in frequency for humans to hear it. There are at least five recognized sub-species of blue whale that occur in different ocean basins. These are
- B. m. musculus, Northern blue whale
- B. m. intermedia, Antarctic blue whale
- B. m. indica, Northern Indian Ocean blue whale
- B. m. brevicauda, Pygmy blue whale
- B. m. un-named subsp., Chilean blue whale.
Pygmy blue whales are smaller and are generally restricted to the Southern Hemisphere including the Indian Ocean. “True” blue whales refer to the larger musculus, intermedia, and indica subspecies. Antarctic blue whales (intermedia) are the largest of the species, but have been severely depleted after decades of whaling. Blue whales are usually found offshore, and their seasonal migrations and breeding and feeding grounds are generally poorly understood. However, there are a few places where they can be seen with some regularity during whale watching trips, such as the Gulf of California in Mexico, the Gulf of St. Lawrence in Canada, the California coast of the United States, and Sri Lanka.