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.

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.

The Yangtze finless porpoise tends to be shy; it does not come to the surface of the water often when there is human activity nearby. They are usually most active when eating and usually spend most of their time near river banks or at the merging of two waterways. Yangtze finless porpoises travel in small groups of about three to six; however groups of 20 have been reported. A radio-tracking study confirmed that the average diving behavior consisted of one long dive followed by two shorter dives. These longer dives were more common during the day time. In the Yangtze River, finless porpoises are known to leap from the water and perform "tail stands". At night the finless porpoises tended to go into sleep cycles and be less active. Another unique behavior reported, but that is not heavily confirmed, is that mothers have been seen carrying calves on their backs.

After the functional extinction of the Yangtze river dolphin and the rapid decreasing of population, the Chinese government has given this species the utmost conservation status of National First Grade Key Protected Wild Animal to ensure its survival. However, the population decrease is accelerating due to lack of food, pollution, and ship movement, and the species has a high chance (86.06%) of becoming extinct within the next 100 years. Another reason that they have been dropping in numbers is because of underwater noise pollution. If spectra levels in the water surpass the underwater acoustic thresholds for the porpoise, their chance of survival is greatly threatened. Global conservation agencies and charities, such as the World Wildlife Fund and IUCN, have been collaborating with the Chinese government to ensure the survival of the species.