The blue whale is not only the largest whale, but also the largest living animal and the largest mammal to date. Some dinosaurs in Mesozoic may be longer than blue whales, but their weight is still difficult to compare with them. It is generally 22-33 meters long and weighs 150000-240000 kg, that is to say, its weight is equivalent to more than 25 African elephants, or the sum of the weights of 2000-3000 people. Fortunately, because of the buoyancy of the ocean, it doesn't need to support its weight as hard as land animals, and its huge body helps to keep a constant body temperature. The whole body surface of the blue whale is light blue or mouse gray, with thin stripes on the back, white spots on the chest and more than 20 folds, and the abdomen is covered with folds all the way to the navel with ochre spots. Female animals have cleavage on both sides of the reproductive opening with slender nipples inside. The head is small and flat, with two spray holes on the top of the head, a wide mouth, no teeth in the mouth and a wide upper jaw. It bulges upward in an arc shape, with 300-400 black whiskers on each side, 90-110cm long and 50-60cm wide. A large amount of earwax accumulates in the eardrum every year, and its age can be judged according to its thickness. It also has a white callus on its upper jaw, which used to be a place for long hair. Later, the hair degenerated, leaving a warty vegetation and becoming a breeding ground for parasites. Because this callus is different for each individual, just like wearing a hat with a different shape, different individuals can be distinguished accordingly. The dorsal fin is extremely short, the length is less than 0.5% of the body length of 65438+, and the flipper limb is not too long, about 4 meters, with four toes, no wavy notch at the back edge, and a wide and flat tail. The whole body is streamlined and looks like a razor, so it is also called "razor whale".