''Neophocaena'' is a genus of

porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals a ...

native to the

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and

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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. Although the term specifically excludes seawater and brackish water, it does incl ...

habitats of the

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. 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 A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

. 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.

References

{{Taxonbar, from=Q10798086 Porpoises Taxa named by Theodore Sherman Palmer Cetacean genera