The blue whale is a marine mammal, not only the largest living animal on Earth, but also the largest animal in the history of the earth, with a total length of more than 30 meters and a weight of 177 tons.
Until the beginning of the 20th century, blue whales were found in almost every part of the world, and after 40 years, whalers hunted them to near extinction. It was not until the international community began conserving blue whales in 1966 that the number of blue whales gradually increased.
The species name musculus comes from Latin and means "strong", but can also be translated as "little mouse". Linnaeus, who probably knew the naming of the species in his seminal 1758 book Systema Naturae, humorously used this ironic pun.
Carl von Linnaeus
Title page of the 1758 edition of Natural Systems
Blue whales are called Sulphur-bottom in Hermann Melville's novel Moby Dick, because diatoms attach to the skin of blue whales, giving them an orange-brown or pale yellowish underside, hence the name Sulphur-bottom whales.
Other common names include the Seabad whale, the Sibbald's Rorqual (named after Robert Seabad), and the Great Blue Whale and the Great Northern Baleen whale and the Giant Baleen Whale, though these names have been forgotten in recent decades.
Current authoritative experts classify blue whales into 3 or 4 subspecies:
.m Musculus: lives in the North Atlantic and North Pacific;
Southern blue whale B.m. intermedia: inhabits the Southern Ocean;
Pygmy Blue Whale B.m. brevicauda: inhabits the Indian and South Pacific Oceans;
Indica: Probably another subspecies that lives in the Indian Ocean..m
Blue whales are considered to be the largest animals ever seen on Earth, and the longest recorded blue whales are two female whales, 33.6 meters and 33.3 meters, but the reliability of these data is questionable. (Most of the data comes from blue whales that humans hunted off in Antarctic waters in the first half of the 20th century, although this data was collected by whalers who are not proficient in standard animal measurement methods.)
Scientists at the National Marine Mammal Laboratory (NMML) measured the longest blue whale at 29.9 meters long.
Reference to the proportion of blue whales to humans and African elephants
Reference to the proportion of blue whales to cruise ships
Skeleton model of a blue whale
Because blue whales are so large, it is difficult to measure their weight. Many whalers hunt blue whales that don't fully measure their weight because they first cut the whale into easy-to-handle sizes. This has led to an underestimation of the total weight of blue whales, as their blood and body fluids are lost.
Until now, scientists at the National Marine Mammal Laboratory have accurately measured that the largest blue whale is a 177-ton female whale. However, female whales are known to be larger than males.
Big data
The blue whale's tongue weighs about 2.7 tons, and when it is fully extended, it can grab 90 tons of food and seawater. Even with such a huge mouth, the throat of a blue whale still cannot swallow an object as wide as a beach ball.
The heart of the blue whale is the size of a car and is also the largest of the known creatures.
The aorta of the blue whale is about 23 cm in diameter.
Blue whales have a lung capacity of 5,000 liters.
Even when they are just born, baby whales can weigh up to 2,700 kilograms, equivalent to the weight of an adult hippopotamus. During the first 7 months of life, baby whales drink 400 litres of breast milk per day. Juveniles grow rapidly, gaining 90 kg of body weight every 24 h.
Controversy over the largest body size
Obsolete depiction of a diplodocus in 1892
Diplodocus, according to the only fossil bone, is estimated to be about 40-60 meters long, while probably weighing about 122 tons. But shortly after describing the dinosaur in the 1870s, the only bone was lost, and the only evidence remains is some illustrations and records.
Megalodon, overall size estimates have not yet been released, but paleontologists and researchers have published preliminary estimates on the Internet. In a June 2001 blog post, Mickey Mortimer estimated that the length of the genus Megalopod could reach 40-44 meters and could weigh 185-250 tons. If the size estimates of the genus Macrosaurus are accurate, then the mature blue whale can reach 30 meters in length much shorter than the genus Macrosaurus; the record holder blue whale weighs 177 tons, but the giant dragon genus weighs 185-250 tons and may become the new record holder.
The fins of blue whales are 3-4 meters long. The upper part of the pectoral fin is grey with narrow white edges, while the underside is all white. Their head and caudal fins are generally grey. Blue whales usually have a variegated back, and sometimes the pectoral fins are also of this color. The degree of variation in markings varies from individual to individual. Some individuals may be gray all over, but others are dark blue, with gray and black mixed with each other.
Blue whales have small dorsal fins and are only briefly visible during the dive. The dorsal fins are located about three-quarters of the body, and their shape varies from individual to individual blue whale, with some individuals having only one bulge that is just right to be recognized, while others may have a pronounced sickle-shaped dorsal fin.
When blue whales are about to surface to breathe, they protrude their shoulders and stomata, which are larger than other large whales such as fin whales and stopper whales. This trait is often identified by observers from marine life to identify their clues.
Some blue whales that inhabit the North Atlantic and North Pacific oceans raise their tail fins when diving.
Blue whales spew out a spectacular vertical column of water, up to 12 meters in height, usually 9 meters, and can be seen from very far distances if the sea is calm.
Blue whales usually live alone or with another blue whale. It is not known whether these cohabiting blue whales live together for a long time or form a more loose relationship. In areas with high food densities, up to 50 blue whales can be seen clustered in small areas, but they do not form large, well-organized groups like other baleen whales.
Blue whales can sprint at short distances of up to 50 km/h, which usually occurs when interacting with other whales, but the usual swimming speed is 20 km/h.
Blue whales always have the densest krill colonies they can find, sometimes preying on 5,000 kilograms of krill a day. Blue whales generally dive for 10 minutes during feeding, although it is not uncommon for them to dive for 20 minutes, while blue whales record the longest dive time of 36 minutes (Sears, 1998).
5.8 m blue whale skull
Baleen board
Krill and krill colonies
Blue whales swallow large flocks of krill at once while feeding, and at the same time inhale large amounts of seawater. They then squeeze their abdominal cavities and tongues to drain the seawater from the gaps in the baleen. When the seawater in the mouth is completely discharged, the blue whale swallows the remaining krill that cannot pass through the baleen board. When blue whales prey on krill, they occasionally swallow small fish, crustaceans and squid.
Whale Song
Cummings and Thompson (1971) show that by measuring a reference pressure of one millipa at a distance of 1 meter from the blue whale, it is estimated that the sound of the blue whale can reach 155-188 decibels at the source. All blue whale populations emit sound at a base frequency between 10-40 hertz, while the lowest frequency that humans can perceive is 20 hertz. The sound duration of the blue whale is 10-30 seconds. Scientists also affirmed why blue whales should make a sound, and Richardson et al. (1995) proposed the following 6 possible reasons:
Maintain distance between individuals
Identification of homogeneous and individual
Environmental information transmission (e.g. foraging, warnings, courtship)
Maintain group contact (e.g., communication between females and males)
Geomorphological feature localization
Food positioning
Blue whales begin mating in late autumn and continue until late winter. Females usually give birth every 2-3 years, and after a gestation period of 10-12 months, they usually give birth to young whales in early winter. The juvenile whale weighs about 2 and a half tons and is about 7 meters long. Consume 380-570 liters of breast milk per day.
Blue whales usually reach sexual maturity between the ages of 8-10 years, when males reach at least 20 meters in length (populations in the southern hemisphere are longer). Female whales, by contrast, are larger and sexually mature around the age of 5, when they are about 21 meters long.
Scientists estimate that blue whales live at least 80 years, but because individual records cannot be traced back to the time of whaling, it will take many years to know the exact lifespan of blue whales. The longest study recorded for a single individual is currently 34 years old, located in the Northeast Pacific (Sears reported in 1998).
killer whale
The only natural predator of blue whales in nature is killer whales. Studies have shown that 25% of adult blue whales have scars from killer whale attacks, but there is no definitive data on the mortality rate from attacks.
There are at least 11 documentations of adult whales born of blue whales and fin whales hybridizing under natural conditions. Hybrids between blue whales and humpback whales are also known.
The Age of Whaling
Blue whales are not easy to catch and slaughter. Their speed and strength mean that blue whales were rarely targeted by early whalers. In 1864, the Norwegian Svend Foyn used a harpoon with a steamship to design to catch large whales. Although initially cumbersome and low-probability of success, Foin further improved the harpoon, and soon several whaling stations in Finnmark County in northern Norway began to use this method to hunt whales. Because of disputes among local fishermen, the last whaling post in Finnmark was closed in 1904.
Soon, blue whales were hunted in Iceland (1883), the Faroe Islands (1894), Newfoundland (1898) and Spitsbergen (1903). Between 1904 and 1905, the first blue whale was captured in southern Georgia, USA.
By 1925, with the advent of the factory stern and the use of steam-powered whale fishing, the number of blue whales and all baleen whales began to increase dramatically in Antarctic and sub-Antarctic waters. Between 1930 and 1931, 29,400 blue whales were killed in Antarctic waters alone. By the end of World War II, the number of blue whales had dwindled considerably.
In 1946, international whale trade quota limits were first introduced, but they did not work because the differences between the different species were not taken into account. Indicates that rare and large numbers of species are hunted and killed by humans to an equal degree.
By the 1960s, the International Whaling Commission began banning the hunting of blue whales, while illegal whaling in the Soviet Union ceased in the 1970s.
By this time more than 380,000 blue whales had been killed, including 330,000 in Antarctic waters, 33,000 in other parts of the Southern Hemisphere, 8,200 in the North Pacific and 7,000 in the North Atlantic. The number of groups that were originally the largest group in Antarctica has fallen to only 0.15% before whaling activities.
Because of the development of the commercial whaling industry, the number of blue whales has declined rapidly
Whaling activity has clearly led to the near extinction of blue whales, and instead of hunting smaller numbers in exchange for longer hunting periods, whalers continue to reduce blue whale populations. It now appears that the monitoring and restrictions set by marine biologists in the whaling industry make more whales potentially of commercial value, albeit over a longer time span. The population dynamics of long-lived marine mammals are quite different from those of shorter-lived fish. Because of longer reproductive periods (more than 1 year) versus fewer births (1 or 2 births per birth), whale populations take longer to recover than smaller animals.
Current number and distribution
Since the ban on whaling, the study could not determine whether the current population of blue whales is increasing or has not changed significantly. The most accurate estimates show that the number of blue whales in antarctica grew at a rate of 7.3% per year after the end of illegal whaling in the Soviet Union, although the overall number is still less than 1% of the original.
Studies have also shown that blue whales inhabitIng Iceland and Canada are also increasing, even if the magnitude is not significantly different. In 2002, scientists estimated that the global blue whale was between 5,000 and 12,000, although estimates in many regions were highly uncertain.
Blue whales are still among the endangered species on the IUCN Red List of Threatened Species, as they were when the list began. The largest known population of blue whales is made up of about 2,000 individuals (northern blue whales), concentrated between Alaska and Costa Rica, although the most common sea area is California during the summer months. Sometimes these blue whales appear in the northwest Pacific Ocean, and there is a rare record of blue whales in the waters between kamchatka and the northern tip of Japan.
Two blue whale groups have already been identified in the North Atlantic. The first, located off the coast of Greenland, Newfoundland, Nova Scotia and the Gulf of St. Lawrence, is estimated to be around 500. Closer to the east, the second group appears in the Azores in the spring and in the waters off Iceland in July and August. Presumably, these whale populations move along the mid-Atlantic ridge between the two volcanic islands. In addition to Iceland, blue whales also occur further north in Svalbard and Jan Mayen, although they are quite rare. But scientists still don't know where the blue whales spend the winter. The population as a whole of the North Atlantic is estimated to be between 600 and 1500.
The results of many recent surveys have shown that the number of subspecies living in the Southern Ocean ranges from 1100 to 1700. A 1996 survey showed that 424 blue whales inhabited a small area of waters south of Madagascar alone. The survey seems to indicate that the number of blue whales throughout the Indian Ocean is in the thousands. If this were the case, the number of blue whales worldwide would be higher than estimated.
Modern threats
Blue whales can be injured when they collide with a vessel or are trapped or entangled in fishing equipment.
Increasing noise in the sea makes it difficult for them to communicate with each other and may even die.
Potential threats to blue whales include the manufacture of chemicals that accumulate in blue whales, polychlorinated biphenyls (PCBs).
With global warming, glaciers and permafrost melt rapidly and cause large amounts of fresh water to be injected into the sea. There are concerns that once the amount of freshwater flowing into the sea exceeds the tipping point, it will lead to the disintegration of the thermohaline circulation. Given the migration patterns of blue whales according to sea temperature, circulation disintegration will cause warm and cold waters to surround the globe, which may affect the migration of blue whales.
Changes in ocean temperatures will also affect the food sources of blue whales, and warming tendencies will also reduce the distribution of salt, which will have a significant impact on their distribution and density.
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