Yangtze Finless Porpoise

A finless porpoise can grow up to 2.27–2.29 m (7 ft 5+1⁄2 in – 7 ft 6 in) in length and weigh up to 71.8–123 kg (158+1⁄4–271+1⁄4 lb), however, most are smaller than this. The average adult is usually 1.5–1.8 m (5–6 ft) in length and weighs around 45 kg (100 lb). Adult females tend to be smaller than adult males. Flippers are curved with pointed ends and are relative large, about 20% of their total body length. The finless porpoise tends to be stocky in the middle body and slimmer towards the tail. In general they are more slender in shape than most other Phocoenidae. These cetaceans also have unique foreheads, with a very steep forehead and no beak. In addition, they have an unfused neck vertebra that allows free head movement. They have 15–22 pairs of teeth on the upper and lower jaw. Body color and dorsal ridge sizes vary depending on the geographical location of the finless porpoise.

Dorsal ridge. As denoted by the name, these finless porpoises have flat backs and are completely finless. Instead of a dorsal fin, these porpoises have a dorsal ridge or "groove" that is covered in varying rows of tubercles. These tubercles are round in shape and raised. Recent studies have found that tubercles do have biological and mechanical functions that benefit the porpoise; for example, the tubercles are a sensory organ and can also help with movement through the water. …

The Yangtze finless porpoise is found in the main body of the Yangtze River and in connecting lakes. They are exclusive to fresh water, making them different from other finless porpoises. They tend to be found in shallow bay areas, swamps, and estuaries year round as they are not a migratory species. However, distribution changes do occur seasonally. In the winter the highest distribution was found in the middle and lower regions of the Yangtze River. Their preferred climate is tropical or warm temperatures.

The diet of the Yangtze finless porpoise may vary according to the season and the dominant prey of the season. This variation in their diet suggest that the Yangtze finless porpoise may be opportunistic feeders. Among the fishes in their diet, the most common are Coilia brachygnathus, Pseudobrama simoni, Pelteobagrus nitidus, and Hemiculter bleekeri.