Blue whale  (Balaenoptera musculus)

The blue whale is the largest animal to have ever lived, almost as big as a Boeing 737 (6), and even larger than the biggest dinosaurs (2). The skin is greyish blue in colour (3) with a mottled effect visible in some lights that can allow individuals to be identified (4). The underside, especially of whales living in polar waters, often has a yellowish tinge caused by microscopic algae (diatoms), and between 55 and 88 throat grooves run from under the chin to the navel (7). The blow (or spout) of this species is the biggest amongst all whales; the slender upright column of air can rise to nine meters (4).