Blue whale (scientific name: Balaenoptera musculus).
Belongs to the marine mammals of the small order Baleen whales. The blue whale is not only the largest living animal on earth, but also one of the largest animals in the history of the earth (it is also a prehistoric giant whale of the genus Balaenoptera sibbaldina, which can rival the blue whale in size. It is more than 33 meters long and weighs 177 metric tons.
The blue whale has a slender body and a bluish-gray back, but the color sometimes looks lighter in the water. There are at least three subspecies of blue whales known: B. m that live in the North Atlantic and North Pacific. . musculus; B. m. intermedia inhabiting the Southern Ocean and B. m. brevicauda (also known as dwarf blue whale) in the Indian Ocean and South Pacific.
B. m. indica is found in the Indian Ocean. Possibly another subspecies. Like other baleen whales, blue whales feed primarily on small crustaceans (such as krill) and sometimes squid. The number of blue whales in almost every sea area in the world was relatively large. After more than 40 years, whalers hunted them almost to extinction. It was not until the international community began to protect blue whales in 1966 that the number of blue whales gradually increased. . A 2002 report estimated that there are currently between 5,000 and 12,000 blue whales in the world, distributed in at least five groups.
Recent research on pygmy blue whales. It is suggested that this figure may be an underestimate of the actual number. Before whaling began, the largest population of blue whales was in Antarctic waters, with an estimated number of approximately 239,000 individuals (range between 202,000 and 311,000).
The current numbers in the Northeast Pacific, Antarctic Sea and Indian Ocean have been greatly reduced (about 2,000 each). There are two larger groups in the North Atlantic, and at least one in the Southern Hemisphere. 2 groups.
Life Cycle
Blue whales mate in late autumn and continue until late winter, but little is known about their mating behavior and breeding areas. Female whales usually give birth once every 2-3 years. After a gestation period of 10-12 months, they usually give birth to calves in early winter.
The calves weigh about 2 and a half tons and are about 7 meters long. m. The calf of a blue whale consumes 380-570 liters of breast milk every day. It can grow nearly 100 kilograms per day at an alarming rate. It will be weaned after 6 months, at which time the calf will be twice as long as when it was born.
Blue whales usually reach sexual maturity between the ages of 8 and 10, when male whales reach at least 20 meters in length (populations in the southern hemisphere are longer). In comparison, female whales are larger, approximately. Sexually mature at age 5, at which time they are approximately 21 meters in length
Scientists estimate that blue whales live at least 80 years, but it is difficult to know because records of individuals do not go back to the whaling era. The exact lifespan of a blue whale will take many years. The current longest research record for a single individual is 34 years, located in the Northeast Pacific (Sears' report in 1998).
Blue whales in nature. The only natural enemy is the killer whale. Research reports show that 25% of adult blue whales have scars left by killer whale attacks, but there is no precise information on the mortality rate caused by attacks.
Blue whale strandings are very rare, and because of their social structure, mass strandings of blue whales have never been heard of. But when a stranding occurs, it will attract public attention. In 1920, a blue whale stranded on the beach of the Isle of Louis in the Outer Hebrides of Scotland. Its head was shot by a whaler, but the harpoon did not explode.
Just like other animals, blue whales instinctively insist on breathing at all costs, and stranding can prevent them from drowning. Two blue whale bones standing next to the avenue on the Isle of Louis attract a large number of tourists.