''Neophocaena'' is a genus of porpoise native to the Indian and

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

oceans, as well as the

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

habitats of the Yangtze River basin in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. They are commonly known as finless porpoises. Genetic studies indicate that ''Neophocaena'' is the most basal living member of the porpoise family. There are three species in this genus:

Description

The finless porpoises are the only porpoises to lack a true dorsal fin. Instead there is a low ridge covered in thick skin bearing several lines of tiny tubercles. In addition, the forehead is unusually steep compared with those of other porpoises. With fifteen to twenty-one teeth in each jaw, they also have, on average, fewer teeth than other porpoises, although there is some overlap, and this is a not a reliable means of distinguishing them. Finless porpoises in Ariake Sound-Tachibana Bay showed ontogenctic and seasonal variations in diet. The mean length at weaning was estimated to be 101 cm, corresponding to approximately 6 months of age. Calves fed on small-sized demersal fish and cephalopods.

References

{{Authority control Porpoises Taxa named by Theodore Sherman Palmer Cetacean genera