Finless porpoise

Neophocaena is a genus of porpoise native to the Indian and Pacific oceans, as well as the freshwater habitats of the Yangtze River basin in China. They are commonly known as finless porpoises. Genetic studies indicate that Neophocaena is the most basal living member of the porpoise family.^[2]

Finless porpoise
Neophocaena sunameri at Miyajima Public Aquarium
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Infraorder:	Cetacea
Family:	Phocoenidae
Genus:	Neophocaena Palmer, 1899
Type species
Delphinus phocaenoides [1] Cuvier, 1829
Species
Neophocaena asiaeorientalis Neophocaena phocaenoides Neophocaena sunameri
For all three finless porpoise species

There are three species in this genus:^[3][4]

Image	Scientific name	Common name	Distribution
	Neophocaena asiaeorientalis	Yangtze finless porpoise	Yangtze River basin in China
	Neophocaena phocaenoides	Indo-Pacific finless porpoise	Persian Gulf east to the Taiwan Strait, south to Indonesia
	Neophocaena sunameri	East Asian finless porpoise	Taiwan Strait north to the Yellow Sea, east to the east coast of Japan

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.^[5] 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. ^[6]

References

1. Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. Rosel, P. E.; et al. (1995). "Phylogenetic relationships among the true porpoises (Cetacea: Phocoenidae)". Molecular Phylogenetics and Evolution. 4 (4): 463–474. doi:10.1006/mpev.1995.1043. PMID 8747302.
3. Mammal Diversity Database (2021-08-10), Mammal Diversity Database, doi:10.5281/zenodo.5175993, retrieved 2021-08-28
4. "Finless Porpoises: Neophocaena phocaenoides, N. asiaeorientalis". Encyclopedia of Marine Mammals: 372–375. 2018-01-01. doi:10.1016/B978-0-12-804327-1.00129-1. ISBN 978-0-12-804327-1.
5. Jefferson, T. A.; Hung, S. K. (2004). "Neophocaena phocaenoides". Mammalian Species. 746: 1–12. doi:10.1644/746. S2CID 198125391.
6. Shirakihara, Miki; Seki, Kenji; Takemura, Akira; Shirakihara, Kunio; Yoshida, Hideyoshi; Yamazaki, Takeshi (2008-10-01). "Food Habits of Finless Porpoises Neophocaena phocaenoides in Western Kyushu, Japan". Journal of Mammalogy. 89 (5): 1248–1256. doi:10.1644/07-MAMM-A-264.1. ISSN 0022-2372.