The blue whale has a long tapering body that appears stretched in comparison with the stockier build of other whales.
[22] The head is flat,
U-shaped and has a prominent ridge running from the
blowhole to the top of the upper lip.
[22]The front part of the mouth is thick with
baleenplates; around 300 plates (each around one metre (3.2 ft) long)
[22] hang from the upper jaw, running 0.5 m (1.6 ft) back into the mouth. Between 70 and 118 grooves (called ventral pleats) run along the throat parallel to the body length. These pleats assist with evacuating water from the mouth after lunge feeding (see feeding below).
The
dorsal fin is small,
[22] ranging in height from 8–70 centimeters (3.1–28 in) (usually 20–40 centimeters (7.9–16 in)) and averaging about 28 centimetres (11 in).
[23] It is visible only briefly during the dive sequence. Located around three-quarters of the way along the length of the body, it varies in shape from one individual to another; some only have a barely perceptible lump, but others may have prominent and falcate (sickle-shaped) dorsals. When surfacing to breathe, the blue whale raises its shoulder and blowhole out of the water to a greater extent than other large whales, such as the fin or sei whales. Observers can use this trait to differentiate between species at sea. Some blue whales in the North Atlantic and North Pacific raise their tail fluke when diving. When breathing, the whale emits a spectacular vertical single-column spout up to 12 metres (39 ft), typically 9 metres (30 ft). Its
lung capacity is 5,000 litres (1320 U.S. gallons). Blue whales have twin blowholes shielded by a large splashguard.
[22]
The flippers are 3–4 metres (9.8–13 ft) long. The upper sides are grey with a thin white border; the lower sides are white. The head and tail fluke are generally uniformly grey. The whale's upper parts, and sometimes the flippers, are usually mottled. The degree of mottling varies substantially from individual to individual. Some may have a uniform slate-grey color, but others demonstrate a considerable variation of dark blues, greys and blacks, all tightly mottled.
[3]
Blue whales can reach speeds of 50 kilometres per hour (31 mph) over short bursts, usually when interacting with other whales, but 20 kilometres per hour (12 mph) is a more typical traveling speed.
[3] When feeding, they slow down to 5 kilometres per hour (3.1 mph).
Blue whales most commonly live alone or with one other individual. It is not known how long traveling pairs stay together. In locations where there is a high concentration of food, as many as 50 blue whales have been seen scattered over a small area. They do not form the large, close-knit groups seen in other baleen species.
Aerial view of a blue whale showing both pectoral fins
Physical description
Size
The small
dorsal fin of this blue whale is just visible on the far left.
The blue whale is the largest animal ever known to have lived.
[22] The largest known
dinosaur of the
Mesozoic Era was
Argentinosaurus,
[24]which is estimated to have weighed up to 90 metric tons (99 short tons).
Blue whales are difficult to weigh because of their size. As is the case with most large whales targeted by whalers, adult blue whales have never been weighed whole, but cut up into manageable pieces first. This caused an underestimate of the total weight of the whale, due to the loss of blood and other fluids. Nevertheless, measurements between 150–170 metric tons (170–190 short tons) were recorded of animals up to 27 metres (89 ft) in length. The weight of an individual 30 metres (98 ft) long is believed by the American
National Marine Mammal Laboratory (NMML) to be in excess of 180 metric tons (200 short tons). The largest blue whale accurately weighed by NMML scientists to date was a female that weighed 177 metric tons (195 short tons).
[9]As a whole, blue whales from the Northern Atlantic and Pacific appear to be smaller on average than those from sub-Antarctic waters.
There is some uncertainty about the biggest blue whale ever found, as most data come from blue whales killed in
Antarctic waters during the first half of the twentieth century, and was collected by whalers not well-versed in standard zoological measurement techniques. The heaviest whale ever recorded weighed in at 190 metric tons (210 short tons).
[25] The longest whales ever recorded were two females measuring 33.6 metres (110 ft) and 33.3 metres (109 ft), although in neither of these cases was the piecemeal weight gathered.
[26] The longest whale measured by scientists at the NMML was 29.9 metres (98 ft),
[9] a female caught in the Antarctic by Japanese whalers in 1946–47. Lieut. Quentin R. Walsh, USCG, while acting as whaling inspector of the factory ship
Ulysses, verified the measurement of a 30 m (98 ft) pregnant blue whale caught in the Antarctic in the 1937–38 season.
[27] The longest reported in the North Pacific was a 27.1 metres (89 ft) female taken by Japanese whalers in 1959, and the longest reported in the North Atlantic was a 28.1 metres (92 ft) female caught in the Davis Strait.
[17]
Due to its large size, several organs of the blue whale are the largest in the animal kingdom. A blue whale's
tongue weighs around 2.7 metric tons (3.0 short tons)
[28] and, when fully expanded, its mouth is large enough to hold up to 90 metric tons (99 short tons) of food and water.
[8] Despite the size of its mouth, the dimensions of its throat are such that a blue whale cannot swallow an object wider than a beach ball.
[29] Its
heart weighs 600 kilograms (1,300 lb) and is the
largest known in any animal.
[28] A blue whale's
aorta is about 23 centimetres (9.1 in) in diameter.
[30] During the first seven months of its life, a blue whale calf drinks approximately 400 litres (100 U.S. gallons) of milk every day. Blue whale calves gain
weight quickly, as much as 90 kilograms (200 lb) every 24 hours. Even at birth, they weigh up to 2,700 kilograms (6,000 lb)—the same as a fully grown
hippopotamus.
[3] Blue whales have relatively small brains, only about 15.25 lbs (6.91 kg), about 0.007% of its body weight
