It is believed that about 20 million years ago the baiji Chinese river dolphin left the ocean and made its home in the Yangtze River in China. Writings from the time of the Han Dynasty in 200 B.C. suggest that several thousands of these animals may have inhabited the Yangtze at that time. Today, researchers estimate that there are probably fewer than 100 baiji in the river, making it the most endangered cetacean in the world.

This species is the only member of this genus. The Latin, Leipo ('left behind') refers to the restricted distribution, whilst vexillifer means 'to bear a banner'.

Its locally known as the Chinese River Dolphin; Yangtze Dolphin; Yangtze River Dolphin; Beiji; Pai C'hi; Whitefin Dolphin; Whiteflag Dolphin. The Baiji has a very long, narrow beak, with abrupt forehead and tiny eyes set high on the sides of the head. The triangular dorsal fin has a blunt peak. They are blue-grey in colour, fading to white below. Maximum length and weight are around 2.5m and 160kg respectively.

The only other cetacean inhabiting the same area as the Baiji is the Finless Porpoise. It is easy to differentiate between the two - the Finless Porpoise has no dorsal, beak or hump, and is less shy than its cousin.

The baiji is found all along the Yangtze River and among sandbars and dikes. The river is wide, open and slow moving. It feeds upon a variety of fish. The Baiji is found in small groups of 3-7 with occasional groups of 10 being observed. Baiji are wary of boats and difficult to approach.