The Life of Animals | Blue Whale | The blue whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti) At 30 metres (98 ft) in length and 180 metric tons (200 short tons) or more in weight, it is the largest known animal to have ever existed Long and slender, the blue whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath There are at least three distinct subspecies: B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia of the Southern Ocean and B. m. brevicauda (also known as the pygmy blue whale) found in the Indian Ocean and South Pacific Ocean. As with other baleen whales, its diet consists almost exclusively of small crustaceans known as krill
Blue whales were abundant in nearly all the oceans on Earth until the beginning of the twentieth century. A 2002 report estimated there were 5,000 to 12,000 blue whales worldwide located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate Before whaling, the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000) There remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. Blue whales are rorquals (family Balaenopteridae), a family that includes the humpback whale, the fin whale, Bryde's whale, the sei whale and the minke whale The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene.
DNA sequencing analysis indicates that the blue whale is phylogenetically closer to the sei whale (Balaenoptera borealis) and Bryde's whale (Balaenoptera brydei) than to other Balaenoptera species, and closer to the humpback whale (Megaptera) and the gray whale (Eschrichtius) than to the minke whales (Balaenoptera acutorostrata and Balaenoptera bonaerensis). Researchers working off of Fiji believe they photographed a hybrid humpback/blue whaleThe first published description of the blue whale comes from Robert Sibbald's Phalainologia Nova (1694). In September 1692, Sibbald found a blue whale that had stranded in the Firth of Forth—a male 78-feet-long—which had "black, horny plates" and "two large apertures approaching a pyramid in shape
Other common names for the blue whale have included Sibbald's rorqual (after Sibbald, who first described the species), the great blue whale and the great northern rorqual. Authorities classify the species into three or four subspecies: B. m. musculus, the northern blue whale consisting of the North Atlantic and North Pacific populations, B. m. intermedia, the southern blue whale of the Southern Ocean, B. m. brevicauda, the pygmy blue whale found in the Indian Ocean and South Pacific and the more problematic B. m. indica, the great Indian rorqual, which is also found in the Indian Ocean and, although described earlier, may be the same subspecies as B. m. brevicauda.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. Some blue whales in the North Atlantic and North Pacific raise their tail fluke when diving. When reathing, the whale emits a spectacular vertical single-column spout up to 12 metres (39 ft), typically 9 metres (30 ft). Blue whales have twin blowholes shielded by a large splashguard
The whale's upper parts, and sometimes the flippers, are usually mottled. substantially from individual to individual. 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 When feeding, they slow down to 5 kilometres per hour (3.1 mph). Blue whales most commonly live alone or with one other individual. In locations where there is a high concentration of food, as many as 50 blue whales have been seen scattered over a small area. Blue whales are difficult to weigh because of their size. Most blue whales killed by whalers were not weighed whole, but cut up into manageable pieces first. The largest blue whale accurately weighed by NMML scientists to date was a female that weighed 177 metric tons (195 short tons) The heaviest whale ever recorded weighed in at 190 metric tons (210 short tons) while the longest whale ever recorded was 33.3 metres (109 ft).
The blue whale is the largest animal ever known to have lived The largest known dinosaur of the Mesozoic Era was the Argentinosaurus, which is estimated to have weighed up to 90 metric tons (99 short tons), though a controversial vertebra of Amphicoelias fragillimus may indicate an animal of up to 122 metric tons (134 short tons) and 40–60 metres (130–200 ft). 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 longest whales ever recorded were two females measuring 33.6 metres (110 ft) and 33.3 metres (109 ft).The longest whale measured by scientists at the NMML was 29.9 metres (98 ft)
A blue whale's tongue weighs around 2.7 metric tons (3.0 short tons) and, when fully expanded, its mouth is large enough to hold up to 90 metric tons (99 short tons) of food and water. 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 Its heart weighs 600 kilograms (1,300 lb) and is the largest known Blue whale calves gain weight quickly, as much as 90 kilograms (200 lb) every 24 hours. Blue whales are not easy to catch or kill. Soon, blue whales were being hunted in Iceland (1883), the Faroe Islands (1894), Newfoundland (1898), and Spitsbergen (1903). In 1904-05 the first blue whales were taken off South Georgia. By 1925, with the advent of the stern slipway in factory ships and the use of steam-driven whale catchers, the catch of blue whales, and baleen whales as a whole, in the Antarctic and sub-Antarctic began to increase dramatically. In the 1930–31 season, these ships caught 29,400 blue whales in the Antarctic alone. Blue whale hunting was banned in 1966 by the International Whaling Commission, and illegal whaling by the USSR finally halted in the 1970s by which time 330,000 blue whales had been caught in the Antarctic, 33,000 in the rest of the Southern Hemisphere, 8,200 in the North Pacific, and 7,000 in the North Atlantic. Since the introduction of the whaling ban, studies have failed to ascertain whether the conservation reliant global blue whale population is increasing or remaining stable. The IUCN Red List counts the blue whale as "endangered" as it has since the list's inception.
This group is estimated to total about 500. Beyond Iceland, blue whales have been spotted as far north as Spitsbergen and Jan Mayen, though such sightings are rare. Scientists do not know where these whales spend their winters. The total North Atlantic population is estimated to be between 600 and 1,500.In the Southern Hemisphere, there appear to be two distinct subspecies, B. m. intermedia, the Antarctic blue whale, and the little-studied pygmy blue whale, B. m. brevicauda, found in Indian Ocean waters. The most recent surveys (midpoint 1998) provided an estimate of 2,280 blue whales in the Antarctic of which fewer than 1% are likely to be pygmy blue whales Estimates from a 1996 survey were that 424 pygmy blue whales were in a small area south of Madagascar alone thus it is likely that numbers in the entire Indian Ocean are in the thousands. For example, pygmy blue whales have been recorded in the northern Indian Ocean (Oman, Maldives and Sri Lanka), where they may form a distinct resident population In addition, the population of blue whales occurring off Chile and Peru may also be a distinct population. Efforts to calculate the blue whale population more accurately are supported by marine mammologists at Duke University, who maintain the Ocean Biogeographic Information System—Spatial Ecological Analysis of Megavertebrate Populations (OBIS-SEAMAP), a collation of marine mammal sighting data from around 130 sources.
