A 300-word English introduction to endangered animal Baiji dolphin

The baiji dolphin, which lived in the Yangtze River for about 25 million years, is an ancient relic of Miocene and Pliocene. Baiji dolphin is a small and medium-sized member of cetacean family, and it is the one with the least head survival among the five existing freshwater dolphins in the world (puffer fish, sub-puffer fish, constant puffer fish, Indian puffer fish and Baiji dolphin). It is also 12 one of the most endangered animals in the world. It originally belonged to the freshwater dolphin family. At the end of 1970s, according to the suggestion of Professor Zhou Kaiya, a Chinese scientist, the baiji family was established separately. It is the only species of the genus Baiji of Cetacea.

Baiji dolphin is spindle-shaped, about 2-2.5 meters long and can weigh more than 200 kilograms. Its mouth is slender, its back is light gray or blue, its abdomen is pure white, its dorsal fin is like a small triangle, its pectoral fin is like two palms, its caudal fin is flat, and its middle part is forked. It is good at swimming, and its speed can reach about 80 kilometers per hour. Living in a muddy river for a long time, the audio-visual organs of Baiji dolphin. Located behind the eyes. But the brain is particularly developed, the sonar system is extremely sensitive, and the head also has ultrasonic function, which can quickly transmit the sound within tens of thousands of meters of rivers to the brain. In case of emergency, it will dive to avoid immediately. Baiji dolphin is cold-tolerant, and its body temperature is usually around 36℃.

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Baiji dolphin mainly lives in the middle and lower reaches of the Yangtze River and its connected waters, such as Dongting Lake, Poyang Lake and Qiantang River. Usually in pairs or above 10, they like to move in deep water and fast water. The existing number is very small. It was estimated that there were only about 300 20 years ago, when they were in danger of extinction.

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Baiji dolphins like to live in groups, especially in the spring mating season. Each group is generally 2- 16. They have a wide range of activities, but often stay in a fixed area for a period of time, and then move to another area after the water temperature changes. They feed on fish.

Baiji dolphin likes to live in the deep waters of rivers, rarely near the shore and ships, but it often swims in shallow waters, chasing fish and shrimp to satisfy its hunger. Its snout is wide and slender, and its upper and lower jaws have more than 130 conical teeth, but it is too lazy to chew, just swallowing fish food with its mouth open, and its digestion ability is very strong. Baiji dolphin often moves in groups or pairs, but people rarely get a chance to see it, only when it comes out of the water.

Baiji dolphins are distributed in the middle and lower reaches of the Yangtze River, about 1, 600 km from Zhicheng, Hubei Province to the Yangtze River estuary. They feed on fish and like to live in groups, with about 2-3 in small groups and 9-65,438+06 in large groups. Baiji dolphin is an aquatic mammal that breathes with its lungs. Every time they breathe, their heads and breathing holes come out of the water first, and then their backs and low triangular dorsal fins come out of the water to breathe. Each diving time is about 20 seconds, and the long diving time can reach 200 seconds. Mature individuals is the longest, with a female of 2.5 meters and a male of 2.3 meters, weighing 100 ~ 150 kg, and constant body temperature, always around 36 degrees Celsius.

Dolphin (bái qí tún), the Yangtze River and white dolphin that lived about 2,500 years ago, is an ancient remnant of Miocene and Pliocene. Beluga whales and dolphins are members of small and medium-sized individual families, and they are among the 5 existing freshwater dolphins in the world (puffer fish, Asian puffer fish, Indian puffer fish and white dolphins), and they are the first to survive at least a few. Because of the huge number of small white dolphins, it is not only listed as a protected species in China, but also 12 of the most endangered animals in the world. The finless porpoise originated in the late 1970s. According to the proposal of Professor Zhou Kaiya, a scientist in China, a separate white dolphin family was established. Umejiro whales and white dolphins are the only dolphin species.

Dolphins are spindle-shaped, about 2-2.5 meters long and can weigh up to 200 kilograms or more. The mouth is slender, the back is light gray or blue, the ventral surface is pure white, the dorsal fin is triangular, the pectoral fins are like palms, and the caudal fin is flat in the middle and bifurcated. It is good at swimming, with a maximum speed of about 80 kilometers per hour. White dolphins and audio-visual organs have deteriorated due to long-term living in muddy rivers. Although its eyes are small, they are blind. The eyes of needles are like ears, and the eyes are at the bottom of the column. However, due to the developed brain, the sonar system is extremely sensitive and has the function of head ultrasound, Jiang can face the sound that quickly enters his mind from tens of thousands of meters away. In case of emergency, they will dive to escape immediately. White dolphins are afraid of cold. The temperature is usually around 36℃.