The blue whale is called Blue Whale in English. There are 4 subspecies. It is not only the largest whale, but also the largest animal in existence and the largest mammal to date.
The species name of the blue whale, musculus, comes from Latin, which means "strong", but can also be translated as "little mouse". Linnaeus, who named the species in his seminal 1758 work Systema Naturae, may have known this and used the ironic pun humorously. The blue whale is called Sulphur-bottom in Herman Melville's novel Moby-Dick, because diatoms cling to its skin, giving its underside an orange-brown or yellowish color. Other common names include Sibbald's Whale, Sibbald's Rorqual (named after Robert Sibbald), Great Blue Whale, and Great Northern Rorqual, but these names have been forgotten in recent decades.
The blue whale has a small dorsal fin that is only briefly visible during a dive. The shape of the dorsal fin varies from individual to individual; some have only a barely visible bump, while others are very prominent and sickle-shaped. The dorsal fin is located approximately three-quarters of the length of the body. When surfacing to breathe, the blue whale raises its shoulder and blowhole area much further out of the water than other large whales (such as fin whales and bream whales). This is often a useful clue for identifying marine species. When breathing, if the weather is calm, the blue whale spits out a spectacular vertical column of water (up to 12 meters, usually 9 meters) that can be seen from thousands of meters away. The blue whale has a lung capacity of 5,000 liters.
When interacting with other whales, the blue whale can sprint at speeds of up to 50 kilometers per hour (30 mph), but usually swims at a speed of 20 kilometers per hour (12 mph). When feeding, the speed drops to 5 kilometers per hour (3 mph). Blue whales in the North Atlantic and North Pacific raise their tail fins when diving, but most other blue whales do not.
The blue whale has a very large head, and 50 people can stand on its tongue. Its heart is as big as a car. A baby can crawl through its arteries, and a newborn blue whale weighs more than an adult elephant. In its first seven months of life, the calf drinks 400 liters (about 100 US gallons) of breast milk every day. The calf grows very quickly, gaining 90 kg every 24 hours.
The blue whale feeds on plankton, mainly krill. A blue whale consumes 2-5 tons of food every day. It swims 2-6 km/h when feeding, 5-33 km/h when migrating, and a maximum of 20-48 km/h when being chased. Generally, 10-20 small dives are followed by a deep dive, with shallow dives separated by 12-20 seconds, and deep dives can last for 10-30 minutes. The spray column is narrow and straight, 6-12 meters high. Krill is the main food of blue whales. The plankton eaten by blue whales belongs to different species depending on the ocean region. In the North Atlantic, northern krill is the main food of blue whales. In the Antarctic, Antarctic krill is the main food of blue whales. Blue whales usually prey on the densest krill schools they can find, which means that blue whales need to forage in deep water (more than 100 meters) during the day and come to the surface to forage at night. The diving time of blue whales during foraging is generally 10 minutes. Diving for 20 minutes is not uncommon, and the longest diving time record is 36 minutes (Sears, 1998). When blue whales are hunting, they swallow a large group of krill at a time, and swallow a large amount of seawater at the same time. Then they squeeze the abdominal cavity and tongue to squeeze out the seawater through the baleen plates. After the seawater in the mouth is completely discharged, the blue whale swallows the remaining krill that cannot pass through the baleen plates.
Although the blue whale lives in the sea, it breathes with lungs like other mammals. The weight of the lungs is more than 1,000 kilograms and can hold more than 1,000 liters of air. Such a large lung capacity greatly reduces the number of times it breathes, and it only surfaces to breathe about once every 10-15 minutes. When breathing, it first expels waste gases such as carbon dioxide in the lungs from the nostrils, and then inhales fresh oxygen. Whenever its head emerges from the water to breathe, it first expels waste gases such as carbon dioxide in the body. When this powerful hot airflow rushes out of the nostrils, the height of the jet can reach about 10 meters, and the nearby seawater is also rolled out of the sea surface, making a spectacular water column appear on the blue sea surface. From a distance, it looks like a sea fountain, and it also makes a loud sound like a train whistle. People call it "spout tide". People can determine the location of a blue whale based on the sound it makes when it sprays, the height and shape of its spray. Blue whales live in all oceans. They are rarely seen in Chinese waters, but there have been records of blue whales appearing in the Yellow Sea and the South China Sea. It usually dives no deeper than 100 meters, but some individuals can dive to a depth of 500 meters, and the diving time can last for 10-20 minutes, followed by 8-15 consecutive sprays.
Generally, whales do not raise their tails before diving, but blue whales always expose their tails to the water before diving, sometimes jumping out of the water high, and then quickly diving into the water 30-40 meters to find food. Usually, it also likes to use its tail fin to splash water, which is a pastime with multiple uses and purposes. It may be playing games, or it may be to attract the attention of companions, or perhaps to get rid of the harassment of parasites on the skin.
The blue whale is the loudest animal in the world. When communicating with its companions, the blue whale uses a low-frequency, deafening sound. This sound can sometimes exceed 180 decibels, which is louder than the sound of a jet taking off when you stand on the runway. A sensitive instrument has detected the sound of a blue whale 80 kilometers away. By measuring the reference pressure of one milliPascal at a distance of one meter from the blue whale, it is estimated that the sound of a blue whale can reach 155-188 decibels at the source. Even considering the different impedances of water and air and different standard reference pressures, the equivalent sound range in air is still 89-122 decibels. For comparison, the sound of a pneumatic drill is about 100 decibels. But humans may not be able to appreciate that the blue whale is the loudest animal. The fundamental frequency of the sound of all blue whale populations is between 10-40 Hz, while the lowest frequency that humans can detect is 20 Hz. The sound of a blue whale lasts for 10-30 seconds. Blue whales off the coast of Sri Lanka have been recorded singing a repetitive four-note "song" that lasts two minutes each time, reminiscent of the song of humpback whales. Researchers believe that because this phenomenon has not been seen in other populations, it may be unique to the B. m. brevicauda (pygmy) subspecies.
Blue whales breed in winter, and females generally give birth once every two years. The gestation period is 10-12 months, and only one calf is born per litter. The calf weighs about two and a half tons and is about seven meters long. To prevent suffocation, the female must lift the calf out of the water for the first breath of air, and then it can breathe on its own. The female has a pair of nipples on both sides of the genital opening. When breastfeeding, she swims in the upper layer of the seawater, and the cub follows closely behind the female. Because the cub does not have movable lips and cannot suck milk by holding the nipple, the female relies on muscle contraction to spray milk directly into the cub's mouth, which is also a good adaptation for life in the water. The milk of the blue whale is very nutritious, and the fat content is 10 times that of cow's milk. The cub sucks more than 1,000 kilograms of milk every day, so it develops very quickly. After 8 months, it can increase to 15 meters and weigh 23,000 kilograms. It can open its mouth to eat various plankton. At the age of 2.5 to 3 years old, the body length can exceed 20 meters. The age of sexual maturity is about 8-10 years old, and the life span is generally over 50 years old, and can live up to 90-100 years old.
The blue whale is one of the most important economic species, with a lot of fat. The international regulations use the blue whale's oil production as the conversion unit, that is, 1 blue whale = 2 fin whales = 2.5 humpback whales = 6 baleen whales. Since the beginning of modern whaling, blue whales have been hunted indiscriminately. In the peak period of 1930-31, nearly 30,000 blue whales were killed in the world in one year. In 1966, the International Whaling Commission announced that the blue whale was a protected object of a ban on hunting. Before the development, there were at least more than 200,000 blue whales, and now it is estimated that there are at most 13,000. According to the statistical report published by the International Whaling Commission in 1989, there are only 200-453 survivors of the blue whale. This is based on an 8-year survey in the southern hemisphere, and it is already on the verge of extinction.
Since the ban on whaling, the global blue whale population has remained roughly the same, at around 3,000-4,000. Blue whales have been listed as endangered on the Red List of Threatened Species since its inception. The largest population of blue whales is in the northeastern Pacific, consisting of about 2,000 individuals, concentrated between Alaska and Costa Rica, but common in California in the summer. This population is the hope for a long-term recovery of blue whales. Sometimes they drift to the northwest Pacific; they have been recorded between Kamchatka and the northern tip of Japan. Humans threaten the recovery of blue whale populations, with polychlorinated biphenyl chemicals accumulating in the blood of blue whales, causing poisoning and premature death, and the noise pollution caused by increasing ocean shipping, which masks the sounds of blue whales and makes it difficult for blue whales to find mates. Changes in ocean temperature will also affect the food source of blue whales, and the warming trend will also reduce the distribution of salt, which will have a significant impact on the distribution and density of blue whales.
Listed in the "Red List of Threatened Species of the World Conservation Union" (IUCN) 2018 ver 3.1-Endangered (EN).
Listed in the first level of China's "National Key Protected Wildlife List" (February 5, 2021).
Listed in Appendix I, Appendix II and Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) 2019 Edition.
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The largest animal on earth is the blue whale. The blue whale is a marine mammal belonging to the suborder Baleen whales. There are four subspecies. The blue whale is considered the largest animal known to have ever lived on earth, reaching a length of 33 meters and weighing 181 tons. The blu...
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