Blue whale (Balaenoptera musculus)
The blue whale (Balaenoptera musculus) is the largest animal to have ever lived, being almost as big as a Boeing 737 and even larger than the biggest dinosaurs. The largest recorded length for a blue whale is 33.5 metres, although most individuals vary between 24 and 27 metres. The heart of this monstrous whale is actually around the size of a Volkswagen Beetle.
Like other rorquals (members of the family Balaenopteridae), the blue whale has a long, somewhat tapered and streamlined body, with the head making up less than one-fourth of its total body length. The rostrum (upper part of the head) is very broad and flat and almost U-shaped, with a single ridge that extends just forward of the blowhole to the tip of the snout. The body is smooth and relatively free of parasites, although a few barnacles may attach to the edge of the tail fluke, the tips of the flippers and to the small, triangular dorsal fin. There is a row of 300 to 400 black baleen plates on each side of the mouth, and approximately 90 throat grooves extend to the navel, which allows the throat to expand enormously during feeding.
The blow (or spout) of this species is the biggest amongst all whales, the slender upright column of air rising up to nine meters. Blue whales in the Northern Hemisphere are generally smaller than those in the Southern Ocean. The female may be up to 10 metres longer than the male.
Despite its common name, the blue whale is actually grayish-blue, with a mottled effect that is visible in some lights and can allow individuals to be identified. The underside often has a yellowish tinge, especially on whales living in polar waters, which is caused by microscopic algae called ‘diatoms’ and led to early whalers giving this species the nickname ‘sulphur bottom whale’.