Morphological characteristics of blue whales
The blue whale is not only the largest whale, but also the largest living animal and the largest mammal to date. Generally, it is 2200-3300 cm long and weighs150,000-180,000 kg. In other words, 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.
Habitat environment of blue whales
The intersection of warm water and cold water is an excellent habitat for blue whales. Cold sea water is usually rich in plankton and krill, which are usually eaten by blue whales. Blue whales are distributed all over the world, with the largest number in Antarctic waters, mainly distributed in temperate and cold seas with water temperature of 5-20℃. Some whales swam in the Yellow Sea and the waters of Taiwan Province Province.
Living habits
food
Most of the bays inhabited by blue whales are flooded with extremely rich organic matter in the river water on the landing land, which makes the water quality very fertile and promotes the massive reproduction of plankton. The dense plankton attracted a large group of krill, and their bodies shone blue like diamonds. The stomach of a blue whale is divided into four parts. The first stomach is caused by partial dilatation of the esophagus, so the appetite is very large. It can swallow about 2 million krill at a time and eat 4000-8000 kilograms every day. If the food in your stomach is less than 2000 kilograms, you will feel hungry. Krill is the most abundant animal in the world, widely distributed in the Arctic and Antarctic waters. It is because there is such a rich food and there is no limit to support weight that blue whales can develop so much. Every day, it spends most of its time swimming in dense plankton. The two rows of plate-like tentacles on its mouth are like a sieve, and its belly has many folds like accordion bellows, which can be expanded and contracted, so that it can swallow seawater and krill together, and then when its mouth is closed, seawater is discharged from the tentacles, filtering out shrimp and fish and swallowing them. Blue whales eat other shrimps, small fish, jellyfish, diatoms and various plankton. In contrast, blue whales living in northern waters are smaller than those living in waters near Antarctica, which is generally considered to be closely related to the types and quantity of their food.
Blue whales feed on plankton, mainly krill. A blue whale consumes 2-5 tons of food every day. Swimming speed is 2-6 km/h when feeding, 5-33 km/h when migrating and 20-48 km/h when being chased. General 10-20 small dive is followed by big dive. Shallow dive interval 12-20 seconds, deep dive sustainable 10-30 minutes. The spray column is narrow and straight, with a height of 6- 12m. Krill is the main food of blue whales, and the plankton eaten by blue whales belong to different species according to different marine areas. In the North Atlantic, northern krill is the main food of blue whales. In Antarctica, Antarctic krill is the main food for blue whales. Blue whales usually prey on the densest krill they can find, which means that blue whales need to feed in deep water (100 meters or more) during the day and can only feed on the surface at night. The diving time of blue whales foraging is generally 10 minute. It is not unusual to dive for 20 minutes, and the longest diving time is 36 minutes (Sears, 1998). In the process of hunting, blue whales swallow a large group of krill at a time and a lot of seawater at the same time. Then squeeze the abdominal cavity and tongue, and squeeze the seawater out through the baleen. When the seawater in the mouth is completely drained, the blue whale will swallow the remaining krill that cannot pass through the baleen whale board.
breathe
Although blue whales live in the sea, like other mammals, they breathe with their lungs, which weigh more than 65,438+0,000 kilograms and can hold more than 65,438+0,000 liters of air. Such a large lung capacity greatly reduces the number of breaths, and only comes out to breathe once every 10- 15 minutes. When breathing, carbon dioxide and other waste gases in the lungs are discharged from the body through the nostrils, and then fresh oxygen is inhaled. Whenever its head comes out of the water to breathe, it will expel carbon dioxide and other waste gases from its body. When this powerful hot airflow rushes out of its nostrils, the jet height can reach about 10 meter, and it will also roll the nearby seawater out of the sea surface, and a spectacular water column will appear on the blue sea surface. From a distance, it looks like a fountain on the sea, and at the same time it makes a loud sound like a train whistle. People call it "jet tide". People can determine the position of the blue whale according to the sound it makes when breathing and the height and shape of the jet. Blue whales live in all oceans. It is extremely rare to see blue whales in China waters, and there are also records of blue whales in the Yellow Sea and the South China Sea. Generally speaking, its diving time does not exceed 100 meters, but some individuals can dive to a depth of 500 meters, and the diving time can last for 10-20 minutes, and then 8- 15 continuous jet.
Generally, whales don't raise their tails before diving, but blue whales always show their tails out of the water before diving, sometimes jumping out of the water very high, and then quickly diving into the water of 30-40 meters to find food. Usually, I also like to draw water with the tail fin, which is a versatile and versatile pastime. It may be playing a game, attracting the attention of its peers, or removing parasites from its skin.
activity
Although some people have seen 50-60 blue whales move in groups, they rarely form groups, most of them are lonely, or only 2-3 of them move together. Amphibious blue whales are very harmonious with each other, swimming, diving, foraging and breathing together, just like mandarin ducks, inseparable, often leaving a wide waterway behind them. Three blue whales get together, mostly females and a calf, close together, followed by males, about 3 meters apart.
Despite its huge size, it usually moves slowly and often stands still, but it can rise and fall freely in the water and its tail swings flexibly. It is not only the driving force for progress, but also acts as a rudder, with a speed of 28 kilometers per hour.
sound
The blue whale is the loudest animal in the world. Blue whales use low-frequency and deafening sounds when communicating with their partners. This kind of sound can sometimes exceed 180 decibels, which is louder than the sound you hear when a jet plane takes off on the runway. A sensitive instrument once detected the sound of blue whales 80 kilometers away. Measured from the reference pressure of 1 m, it is estimated that the sound of the blue whale can reach 155- 188 decibels at the sound source. Even considering the different impedances and standard reference pressures of water and air, the equivalent range in air is still 89- 122 dB. In contrast, the sound of a pneumatic drill is about 100 decibel. But humans may not realize that the blue whale is the loudest animal. The fundamental frequency of all blue whale populations is 10-40 Hz, and the lowest frequency that humans can detect is 20 Hz. The sound duration of the blue whale is 10-30 seconds. According to records, the sound of blue whales off the coast of Sri Lanka repeatedly sings a four-note "song", which lasts for two minutes at a time, reminding people of the song of humpback whales. The researchers believe that because this phenomenon has not been seen in other populations, it may be unique to B. m. brevicauda (dwarf) subspecies.