Baiji dolphin, a national first-class protected animal, is also known as Baiji dolphin, Baiji dolphin and Baiji dolphin. Vertebrates, mammals, whales, toothed whales. The baiji family was originally a freshwater dolphin, which was founded in the late 1970s at the suggestion of Professor Zhou Kaiya, a scientist in China. The only species of the genus Baiji in Cetacea. Freshwater toothed whale is a specialty of China, distributed in the middle and lower reaches of the Yangtze River. Dongting Lake, Poyang Lake and Qiantang River are also available. The body is spindle-shaped, with a body length of 1.5 ~ 2.5 meters and a weight of 230 kg. The snout is beak-shaped, narrow and long, and the tip of the snout is slightly upturned; Frontal eminence; Small eyes, located under the squab; Ear hole is very small, shaped like a needle eye, located in the back and lower part of the eye; The dorsal fin is a low isosceles triangle, located in the middle of the back, slightly behind; The fin limb is wide, the end is round and blunt, and the trailing edge of the caudal fin is concave crescent; The back is gray or blue-gray, and the ventral surface is white. Dorsal fin, dorsal fin and caudal fin are all gray or blue-gray. When breathing, the head comes out first, the splash is not high, and the tail fin does not come out. Baiji dolphin is good at diving, but it is easy to be injured by the propeller of motorboat and die. Usually in pairs. Feeding on fish, you can catch benthic fish with a long beak.

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. Like to live in groups, especially in the spring mating season, group behavior is more obvious. Each group generally has 2-6 heads. It has a wide range of activities, but it requires high hydrological conditions. It often stays in a fixed area for a period of time, and then moves to another area after the hydrological conditions change. Feed on fish. Baiji dolphins breed every two years, each offspring 1, and the body length is about 80 cm at birth. The newborn larvae are slightly darker in color, and the adult baiji generally has a light blue-gray back and a clean white abdomen, which is particularly bright under the sunlight. The upper and lower surfaces of horizontally extending flippers and caudal fins are the same color as the back and ventral surfaces, respectively, so the color distribution is just in line with the environmental color. Looking down from the water surface, it is difficult to distinguish the bluish gray on the back from the river water; Looking up from the bottom of the water, it is difficult to find that the white belly is similar to the strong light reflected from the water surface. This makes the baiji have a natural hidden barrier when fleeing from the enemy and approaching the prey. The life span of baiji dolphin can reach more than 30 years. Generally speaking, females reach sexual maturity at the age of 6 and males at the age of 4. Adult baiji is in estrus twice a year, from March to May and from August to 10. The gestation period is10-1month, with one litter and occasionally two litters. In the wild, the male-female ratio of adult baiji is 1: 1, but the pregnancy rate of females is generally only 30%, and the natural reproduction rate is very low.