The Largest Mammal

Balaenoptera musculus, also known as the Blue Whale, is a type of marine mammal with baleen. With a maximum verified length of 29.9 meters (98 feet) and a maximum weight of 199 tonnes (196 long tons; 219 short tons), it is the biggest animal that has ever been discovered.

In The tall, slender body of a blue whale can have several dorsal tints of greyish-blue and a darker underside. In the North Atlantic and North Pacific, B. m. musculus is the recognized subspecies; in the Southern Ocean, B. m. intermedia; in the Indian and South Pacific Oceans, B. m. brevicauda, or pygmy blue whale; and in the Northern Indian Ocean, B. m. indica. Another population that might make up a fifth subspecies is found in the waters off of Chile.




Nomenclature


The name "musculus" for the species in Systema Naturae may have been a pun by Carl Linnaeus, who named the species. The genus name Balaenoptera means winged whale.In [9] In 1692, Robert Sibbald saw a stranded whale in the estuary of the Firth of Forth, Scotland, and went on to write one of the earliest accounts of a blue whale in his Phalainologia Nova.

The term "blue whale" originated from the Norwegian word "blåhval," which was first used by Svend Foyn not long after he managed to perfect the harpoon gun. It was adopted as the common name in 1874 by the Norwegian scientist G. O. Sars.


Evolution


The Balaenopteridae family includes blue whales as rorquals. The Balaenopteridae family separated from other families between 10.48 and 4.98 million years ago during the late Miocene, according to a 2018 research.

A fragmentary skull fossil from the Early Pleistocene, or approximately 1.5–1.25 million years ago, was unearthed in southern Italy and is the earliest known example of anatomically contemporary blue whale.During the Last Glacial Maximum, the Australian pygmy blue whale diverged. The subspecies has a low genetic diversity due to their more recent divergence, and the genetic diversity of New Zealand blue whales is even lower.

Gray whales are the sister group to which blue whales are most closely related, according to whole genome sequencing. 


Satellite Monitoring


Blue whales use the Gulf of Corcovado in southern Chile as a major feeding place. On the other hand, both industrial and artisanal fisheries use it, and the nation's many salmon farms are located there. Together, they provide whales with a variety of risks, including vessel strikes, bycatch, and marine debris. With the use of satellite tags, WWF is able to determine the precise routes and places that the whales frequent. To avoid conflicts between whales and salmon farms or wild-caught fisheries, this information will be useful in making choices concerning protected areas.

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Hybridization


Since then, there have been reports of two blue-fin whale hybrids in the Gulf of St. Lawrence (Canada) and the Azores (Portugal). DNA tests conducted on a blue whale killed in July 2018 by the Icelandic whaling business Hvalur hf revealed that the whale was the progeny of a female blue whale and a male fin whale; but the findings are subject to additional independent testing and sample verification. 

Blue whales are considered "Protection Stocks" by the International Whaling Commission, hence trafficking their meat is prohibited and the kill is a crime that needs to be recorded. By analyzing whale meat samples from Japanese markets genetically, blue-fin hybrids have been found. Hybrid bluefin whales are potentially reproductive.


SIZE


According to some studies, the size of the ancient whale Perucetus and some shastasaurd ichthyosaurs may have rivaled that of the blue whale. Perucetus also weighed more than the blue whale, with a mean weight of 180 t (180 long tons); however, these estimates are based on fragmentary remains, and the proposed size for the latter has been disputed in 2024.

 Similarly, (mean weight: 110–170 tons) and Maraapunisaurus (mean weight: 80–120 tons) would have easily rivaled the blue whale on land; in fact, the former would have likely outweighed the whale even at its most generous estimates of 240 tons. However, these estimates are based on even more fragmentary specimens that had disintegrated by the time those estimates were made.


Description

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A narrow, U-shaped head, long, thin flippers, a short, sickle-shaped dorsal fin at the tail measuring 33 centimeters (13 in), and a big tail stock situated at the base of the wide, thin flukes characterize the blue whale. Between 70 and 395 black baleen plates line the upper jaw. There are 60–88 grooves in the throat area, which permit the skin to swell during eating.

 It has two blowholes that may shoot upwards to 9.1–12.2 meters (30–40 feet). Underwater, the skin appears blue due to its uneven grayish-blue hue. Each individual has a different pattern of mottling close to the dorsal fin. Due to diatoms in the water, the underbelly's coloring is lighter and it may seem yellow. 


Invertebrates and parasites


Although the number of fatal attacks by orcas is unclear, orcas are the only known natural predators of blue whales. Based on studies on photograph identification, it has been predicted that a significant number of blue whales in the Gulf of California bear scars resembling rakes, which are believed to be signs of interactions with orcas. Rake markings were found on 3.7% of blue whales photographed off the coast of Southeast Australia and 42.1% of photographed pygmy blue whales off the coast of Western Australia. Rarely have orcas been observed to prey. The first sighting of a blue whale mother and calf being pursued by orcas at great speed occurred off the coast of southeast Australia. The injured whale fled after five hours in the first attack that was ever recorded, which happened in 1977 off the southwest coast of Baja California, Mexico.


Threats

On the flensing platform, a dead blue whale

Because of their size and speed, blue whales were previously challenging to hunt. When projectile-capable harpoons were developed in the middle of the 19th century, this started to alter.  The greatest years for blue whale whaling were 1930–1931 when 30,000 animals were captured. The Antarctic saw a particularly high level of whale harvesting in the early half of the 20th century, with 350,000–360,000 whales taken out of the species. 9,500 whales in the North Pacific and 11,000 in the North Atlantic (mainly near Iceland) perished in the same time frame.

 In 1966, the International Whaling Commission outlawed the hunting of blue whales and granted them global protection.Reference 125 Up into the 1970s, though, the Soviet Union persisted in its illicit hunting of blue whales and other animals.

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