List of cetaceans

IUCN Red List categories
Conservation status
EW	Extinct in the wild
CR	Critically endangered
EN	Endangered
VU	Vulnerable
NT	Near threatened
CD	Conservation dependent
LC	Least Concern
Other category
DD	Data deficient
NE	Not evaluated

Cetaceans – whales, dolphins and porpoises – are placental marine mammals. All modern members of the infraorder are fully aquatic and live in the open ocean (except a few species of dolphin which inhabit rivers and estuaries). Cetaceans mate, give birth, suckle their young, and feed exclusively underwater. They range in size from the 1.4-metre (4.6 ft) and 54-kilogram (119 lb) vaquita to the 29.9-metre (98 ft) and 190-metric-ton (210-short-ton) blue whale, which is also the largest creature that has ever existed. Fourteen families, 39 genera, and 88 species of cetaceans are recognised by the International Union for Conservation of Nature (IUCN). Of the 88 species, the IUCN classifies three as Critically Endangered, seven as Endangered, six as Vulnerable, five as Near Threatened, twenty two as Least Concern, and 45 as Data Deficient.^[7]

Cetaceans are characterized by a fusiform body, paddle-shaped front limbs and vestigial hind limbs. Their tails have been flattened into flukes to aid propulsion. They have lungs, and must surface regularly to breathe air through blowholes (modified nostrils) situated on the top of the cranium. The cetaceans are included in the order Cetartiodactyla^{[lower-alpha 2]} with the Artiodactyla (the even-toed ungulates). Previously, they were placed within their own order, Cetacea, now an infraorder. They are divided into two subgroups, the Odontoceti (the toothed whales, including dolphins and porpoises) and the Mysticeti (the baleen whales), formerly suborders but now considered parvorders or unranked taxa. There are 89 living species of cetaceans (including the functionally extinct Chinese river dolphin).^[10] In addition, numerous species of extinct cetaceans have been documented, but they are not listed here. This list contains only the known, extant cetacean species including several recently defined species.

Cetaceans are widespread, but some, as with the mysticetes, specialise in certain environments. Most mysticetes prefer the colder waters of the Northern and Southern Hemispheres, and migrate to the equator to give birth. Odontocetes feed largely on fish and squid, but a few, like the killer whale, feed on mammals, such as pinnipeds. Gray whales are specialized for feeding on bottom-dwelling mollusks. Males typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Some whales produce a variety of vocalizations, notably the songs of the humpback whale. Many species, mainly dolphins, are highly sociable, with some pods reaching over a thousand individuals.^[11]

Once relentlessly hunted for their products, whales are now protected by international law. Some species are attributed with high levels of intelligence. At the 2012 meeting of the American Association for the Advancement of Science, support was reiterated for a cetacean bill of rights, listing cetaceans as non-human persons.^[12] The North Atlantic right whales nearly became extinct in the twentieth century, with a population low of 450, and are considered functionally extinct by cetologists.^[13] The baiji is also considered functionally extinct by the IUCN with, the last sighting in 2004.^[10] Besides whaling, they also face threats from bycatch and marine pollution. The meat, blubber and baleen of whales have traditionally been used by indigenous peoples of the Arctic. Whales occasionally feature in literature and film, as in the great white whale of Herman Melville's Moby Dick. Small cetaceans, mainly dolphins, are kept in captivity and trained to perform tricks, but breeding success has been poor. Whale watching has become a form of tourism around the world.

Conventions

Conservation status

Conservation status codes listed follow the IUCN red list of threatened species (v. 2014.3; data current at 20 January 2015).^[14]

Global population estimates

Where available, the global population estimate has been listed. When not cited or footnoted differently, these are from the IUCN red list of threatened species (v. 2014.3; data current at 20 January 2015).^[14]

Mysticeti: baleen whales

The baleen whales, also called whalebone whales or great whales, form the Mysticeti. Baleen whales are characterized by having baleen plates for filter feeding and two blowholes. During the embryonic phase, Mysticetes do have teeth but they are reabsorbed before birth ^[15]

Family Balaenidae: right whales

The family Balaenidae contains two genera and four species. All the Balaenidae whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; long, narrow, elastic baleen plates (up to 9 times longer than wide) with fine baleen fringes; and fused cervical vertebrae rendering the head immobile.^[16]

Genus Balaena Linnaeus, 1758 – one species
Common name	Scientific name	IUCN Red List Status	Global Population Estimate	Range	Size	Picture
Bowhead whale	Balaena mysticetus Linnaeus, 1758	LC IUCN	12,682–39,950		60 tonnes
Genus Eubalaena Gray, 1864 – 3 species
Common name	Scientific name	IUCN Red List Status	Global Population Estimate	Range	Size	Picture
North Atlantic right whale	Eubalaena glacialis Müller, 1776	EN IUCN	300-350		40–80 tonnes
North Pacific right whale	Eubalaena japonica Lacépède, 1818	EN IUCN	404-2,108[17]		60–80 tonnes
Southern right whale	Eubalaena australis Desmoulins, 1822	LC IUCN	7,500		40–80 tonnes

Family Balaenopteridae: rorquals

Rorquals are the largest group of baleen whales, with 9 species in two genera. They include the largest animal that has ever lived, the blue whale, which can reach 190 tonnes, the fin whale can easily reach 50 tonnes, and even the smallest of the group, the northern minke whale, reaches 9 tonnes. They take their name from a Norwegian word meaning "furrow whale": all members of the family have a series of longitudinal folds of skin running from below the mouth back to the navel (except the sei whale, which has shorter grooves). These are understood to allow the mouth to expand immensely when feeding.^[18] All rorquals have ventral grooves, and are the only cetaceans to have them. Additionally, they all have dorsal fins, broad, gently curving rostra and short baleen plates.^[16]

Subfamily Balaenopterinae – one genus, eight species
Genus Balaenoptera – eight species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Blue whale	Balaenoptera musculus Linnaeus, 1758	EN IUCN	10,000-25,000		73-136 tonnes
Bryde's whale	Balaenoptera brydei Olsen, 1913	DD IUCN	90,000–100,000		14–30 tonnes
Common minke whale	Balaenoptera acutorostrata Lacépède, 1804	LC IUCN	Unknown		6-11 tonnes
Eden's whale	Balaenoptera edeni Anderson, 1879	DD IUCN	Unknown		Unknown
Fin whale	Balaenoptera physalus Linnaeus, 1758	EN IUCN	100,000		30–80 tonnes
Omura's whale	Balaenoptera omurai Wada et al., 2003	DD IUCN	Unknown	Unknown	Unknown
Sei whale	Balaenoptera borealis Lesson, 1828	EN IUCN	57,000		20–25 tonnes
Southern minke whale	Balaenoptera bonaerensis Burmeister, 1867	DD IUCN	515,000		6-10 tonnes
Subfamily Megapterinae – 1 genus, 1 species
Genus Megaptera Gray, 1846 – 1 species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Humpback whale	Megaptera novaeangliae Borowski, 1781	LC IUCN	80,000		25–30 tonnes

Family Cetotheriidae: pygmy right whale

The pygmy right whale shares several characteristics with the right whales, although having dorsal fins separates them from right whales, and they have a very distinctive jaw configuration. Pygmy right whales' heads are no more than one-fourth the size of their bodies, whereas the right whales' heads are about one-third the size of their bodies.^[16]

Genus Caperea Gray, 1864 – 1 species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Pygmy right whale	Caperea marginata Gray, 1846	DD IUCN	Unknown		3-3.5 tonnes

Family Eschrichtiidae: gray whale

The gray whale has been placed in a family of its own as it is sufficiently different from the right whales and the rorquals. The gray whale is the only benthic feeding baleen whale, filtering small organisms from the mud of shallow seas. They also have a gestation period of over a year, which is unusual for baleen whales.^[16]

Genus Eschrichtius – 1 species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Gray whale	Eschrichtius robustus Lilljeborg, 1861	LC IUCN	26,000		15–40 tonnes

Odontoceti: toothed whales

The toothed whales (systematic name Odontoceti) form a parvorder of the cetaceans. As the name suggests, the parvorder is characterized by having teeth (rather than baleen). Toothed whales are active hunters, feeding on fish, squid, and in some cases other marine mammals.

Family Delphinidae: oceanic dolphins

Oceanic dolphins are the members of the cetacean family Delphinidae. These aquatic mammals are related to whales and porpoises. As the name implies, these dolphins tend to be found in the open seas, unlike the river dolphins, although a few species such as the Irrawaddy dolphin are coastal or riverine. Six of the larger species in the Delphinidae, the killer whale (orca) and its relatives, are commonly called whales, rather than dolphins. They are also sometimes collectively known as "blackfish".

The Delphinidae are characterized by having distinct beaks (unlike the Phocoenidae), two or more fused cervical vertebrae and 20 or more pairs of teeth in their upper jaws. None is more than 4 m long.^[16]

Genus Cephalorhynchus Gray, 1846 – four species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Chilean dolphin	Cephalorhynchus eutropia Gray, 1846	NT IUCN	Unknown		60 kg
Commerson's dolphin	Cephalorhynchus commersonii Lacépède, 1804	DD IUCN	3,400		35–60 kilograms
Heaviside's dolphin	Cephalorhynchus heavisidii Gray, 1828	DD IUCN	Unknown		40–75 kg
Hector's dolphin	Cephalorhynchus hectori Van Beneden, 1881	EN IUCN (subspecies Maui's dolphin CR IUCN)	2,000–2,500 (subspecies Maui's 55 in 2012)		35–60 kg
Genus Delphinus – three species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Arabian common dolphin	Delphinus tropicalis van Bree, 1971	NE	Unknown	(cetacean needed)	65–105 kg
Long-beaked common dolphin	Delphinus capensis Gray, 1828	DD IUCN	Unknown [lower-alpha 3]		80–150 kg	(cetacean needed)
Short-beaked common dolphin	Delphinus delphis Linnaeus, 1758	LC IUCN			70–110 kg
Genus Feresa – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Pygmy killer whale	Feresa attenuata Gray, 1875	DD IUCN	Unknown [lower-alpha 4]		160–350 kg
Genus Globicephala – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Long-finned pilot whale	Globicephala melas Traill, 1809	DD IUCN	Unknown [lower-alpha 5]		3-3.5 tonnes
Short-finned pilot whale	Globicephala macrorhynchus Gray, 1846	DD IUCN	Unknown [lower-alpha 6]		1–3 tonnes
Genus Grampus – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Risso's dolphin	Grampus griseus G. Cuvier, 1812	LC IUCN	Unknown [lower-alpha 7]		300 kg
Genus Lagenodelphis – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Fraser's dolphin	Lagenodelphis hosei Fraser, 1956	LC IUCN	Unknown		209 kg
Genus Lagenorhynchus Gray, 1846 – six species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Atlantic white-sided dolphin	Lagenorhynchus acutus Gray, 1828	LC IUCN	200,000 – 300,000		235 kg
Dusky dolphin	Lagenorhynchus obscurus Gray, 1828	DD IUCN	Unknown		100 kg
Hourglass dolphin	Lagenorhynchus cruciger Quoy & Gaimard, 1824	LC IUCN	140,000		90–120 kg
Pacific white-sided dolphin	Lagenorhynchus obliquidens Gill, 1865	LC IUCN	1,000,000		85–150 kg
Peale's dolphin	Lagenorhynchus australis Peale, 1848	DD IUCN	Unknown [lower-alpha 8]		115 kg
White-beaked dolphin	Lagenorhynchus albirostris Gray, 1846	LC IUCN	100,000 [lower-alpha 9]		180 kg
Genus Lissodelphis – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Northern right whale dolphin	Lissodelphis borealis Peale, 1848	LC IUCN	400,000 [lower-alpha 10]		115 kg
Southern right whale dolphin	Lissodelphis peronii Lacépède, 1804	DD IUCN	Unknown [lower-alpha 11]		60–100 kg
Genus Orcaella Gray, 1866 – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Australian snubfin dolphin	Orcaella heinsohni Beasley, Robertson & Arnold, 2005	NT IUCN	Unknown		130–145 kg
Irrawaddy dolphin	Orcaella brevirostris Gray, 1866	VU IUCN	Unknown		130 kg
Genus Orcinus – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Killer whale	Orcinus orca Linnaeus, 1758	DD IUCN	100,000 [lower-alpha 12]		4.5 tonnes
Genus Peponocephala – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Melon-headed whale	Peponocephala electra Gray, 1846	LC IUCN	Unknown [lower-alpha 13]		225 kg
Genus Pseudorca – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
False killer whale	Pseudorca crassidens Owen, 1846	DD IUCN	Unknown [lower-alpha 14]		1.5-2 tonnes
Genus Sousa – three species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Atlantic humpback dolphin	Sousa teuszi Kükenthal, 1892	DD IUCN	Unknown		100–150 kg	(cetacean needed)
Indian humpback dolphin	Sousa plumbea Cuvier, 1829	DD	Unknown		150–200 kg
Pacific humpback dolphin	Sousa chinensis Osbeck, 1765	DD IUCN	Unknown		250–280 kg
Genus Sotalia – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Costero	Sotalia guianensis Bénéden, 1864	DD IUCN	Unknown	Solid color	35–45 kg
Tucuxi	Sotalia fluviatilis Gervais & Deville, 1853	DD IUCN	Unknown	Hashed color	35–45 kg
Genus Stenella Gray, 1866 – five species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Atlantic spotted dolphin	Stenella frontalis Cuvier, 1829	DD IUCN	100,000		100 kg
Clymene dolphin	Stenella clymene Gray, 1846	DD IUCN	Unknown		75–80 kg
Pantropical spotted dolphin	Stenella attenuata Gray, 1846	CD IUCN	3,000,000		100 kg
Spinner dolphin	Stenella longirostris Gray, 1828	DD IUCN	Unknown		90 kg
Striped dolphin	Stenella coeruleoalba Meyen, 1833	CD IUCN	2,000,000		100 kg
Genus Steno – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Rough-toothed dolphin	Steno bredanensis Lesson, 1828	LC IUCN	150,000		100–135 kg
Genus Tursiops – three species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Burrunan dolphin	Tursiops australis	NE	Unknown
Common bottlenose dolphin	Tursiops truncatus Montagu, 1821	LC IUCN	Unknown		150–650 kg
Indo-Pacific bottlenose dolphin	Tursiops aduncus Ehrenberg, 1833	DD IUCN	Unknown		230 kg

Family Monodontidae: narwhal and beluga

The cetacean family Monodontidae comprises two unusual whale species, the narwhal, in which the male has a long tusk, and the white beluga.

The Monodontidae lack dorsal fins, which have been replaced by tough, fibrous ridges just behind the midpoints of their bodies and are probably an adaptation to swimming under ice, as both do in their Arctic habitat. The flippers are small, rounded and tend to curl up at the ends in adulthood. All, or almost all, the cervical vertebrae are unfused, allowing their heads to be turned independently of their bodies. None has any throat grooves.^[16]

Genus Delphinapterus – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Beluga	Delphinapterus leucas Pallas, 1776	NT IUCN	100,000 [lower-alpha 15]		1.5 tonnes
Genus Monodon – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Narwhal(e)	Monodon monoceros Linnaeus, 1758	NT IUCN	25,000 [lower-alpha 16]		900-1,500 kilograms

Family Kogiidae: dwarf and pygmy sperm whales

The dwarf and pygmy sperm whales resemble sperm whales, but are far smaller. They are dark gray, dorsally, while ventrally they are lighter. They have blunt, squarish heads with narrow, underslung jaws; the flippers are set far forward, close to the head and their dorsal fins are set far back down the body.

Genus Kogia – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Dwarf sperm whale	Kogia sima Owen, 1866	DD IUCN	Unknown [lower-alpha 17]		250 kg
Pygmy sperm whale	Kogia breviceps Blainville, 1838	DD IUCN	Unknown [lower-alpha 18]		400 kg

Family Phocoenidae: porpoises

Porpoises are small cetaceans of the family Phocoenidae. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is porpoises have spatulate (flattened) teeth distinct from the conical teeth of dolphins. In addition, porpoises are relatively r-selected compared with dolphins: that is, they rear more young more quickly than dolphins. All seven species have small flippers, notched tail flukes, and no beaks. All carry at least 11 pairs of small teeth in their upper and lower jaws.

Porpoises, divided into seven species, live in all oceans, mostly near the shore. Probably best known is the harbour porpoise, which can be found across the Northern Hemisphere.

Genus Neophocaena – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Indo-pacific finless porpoise	Neophocaena phocaenoides Cuvier, 1829	VU IUCN[lower-alpha 19]	Unknown [lower-alpha 20]		30–45 kg
Narrow-ridged finless porpoise	Neophocaena asiaeorientalis Cuvier, 1829	CR IUCN[lower-alpha 21]	1,000	red color	30–45 kg
Genus Phocoena – four species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Burmeister's porpoise	Phocoena spinipinnis Burmeister, 1865	DD IUCN	Unknown [lower-alpha 22]		50–75 kg	(cetacean needed)
Harbour porpoise	Phocoena phocoena Linnaeus, 1758	LC IUCN	700,000 [19]		75 kg
Spectacled porpoise	Phocoena dioptrica Lahille, 1912	DD IUCN	Unknown [lower-alpha 23]		60–84 kg	(cetacean needed)
Vaquita	Phocoena sinus Norris & McFarland, 1958	CR IUCN	500 [lower-alpha 24]		50 kg
Genus Phocoenoides – 1 species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Dall's porpoise	Phocoenoides dalli True, 1885	LC IUCN	1,100,000 [lower-alpha 25]		130–200 kg

Family Physeteridae: sperm whale

The sperm whale characteristically has a large, squarish head one-third the length of its body; the blowhole is slightly to the left hand side; the skin is usually wrinkled; and it has no teeth on the upper jaw.

Genus Physeter – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Sperm whale	Physeter macrocephalus Linnaeus, 1758	VU IUCN	200,000–2,000,000 [lower-alpha 26]		25–50 tonnes

Family Ziphiidae: beaked whales

A beaked whale is any of at least 21 species of small whale in the family Ziphiidae. They are one of the least-known families of large mammals: several species have only been described in the last two decades, and it is entirely possible that more remain as yet undiscovered. Six genera have been identified.

They possess a unique feeding mechanism known as suction feeding. Instead of catching their prey with teeth, it is sucked into their oral cavity. Their tongue can move very freely, and when suddenly retracted at the same time as the gular floor is distended, the pressure immediately drops within their mouth and the prey is sucked in with the water. The family members are characterized by having a lower jaw that extends at least to the tip of the upper jaw, a shallow or non-existent notch between the tail flukes, a dorsal fin set well back on the body, three of four fused cervical vertebrae, extensive skull asymmetry and two conspicuous throat grooves forming a 'V' pattern.^[16]

Genus Berardius – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Arnoux's beaked whale	Berardius arnuxii Duvernoy, 1851	DD IUCN	Unknown [lower-alpha 27]		8 tonnes
Baird's beaked whale	Berardius bairdii Stejneger, 1883	DD IUCN	Unknown [lower-alpha 28]		12 tonnes	(cetacean needed)
Genus Tasmacetus – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Shepherd's beaked whale	Tasmacetus shepherdi Oliver, 1937	DD IUCN	Unknown [lower-alpha 29]		2-2.5 tonnes	(cetacean needed)
Genus Ziphius – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Cuvier's beaked whale	Ziphius cavirostris G. Cuvier, 1823	LC	Unknown [lower-alpha 30]		2–3 tonnes
Subfamily Hyperoodontinae – three genera, 17 species
Genus Hyperoodon – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Northern bottlenose whale	Hyperoodon ampullatus Forster, 1770	DD IUCN	10,000 [lower-alpha 31]		7 tonnes
Southern bottlenose whale	Hyperoodon planifrons Flower, 1882	LC IUCN	500,000		6 tonnes	(cetacean needed)
Genus Indopacetus – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Tropical bottlenose whale	Indopacetus pacificus Longman, 1926	DD IUCN	Unknown [lower-alpha 32]		3,5-4 tonnes	(cetacean needed)
Genus Mesoplodon Gervais, 1850 – 14 species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Andrews' beaked whale	Mesoplodon bowdoini Andrews, 1908	DD IUCN	Unknown		1 tonne
Blainville's beaked whale	Mesoplodon densirostris Blainville, 1817	DD IUCN	Unknown
Gervais' beaked whale	Mesoplodon europaeus Gervais, 1855	DD IUCN	Unknown		1.2 tonnes	(cetacean needed)
Ginkgo-toothed beaked whale	Mesoplodon ginkgodens Nishiwaki & Kamiya, 1958	DD IUCN	Unknown		1.5 tonnes
Gray's beaked whale	Mesoplodon grayi von Haast, 1876	DD IUCN	Unknown		1.5 tonnes
Hector's beaked whale	Mesoplodon hectori Gray, 1871	DD IUCN	Unknown		1 tonne
Hubbs' beaked whale	Mesoplodon carlhubbsi Moore, 1963	DD IUCN	Unknown		1.4 tonnes	(cetacean needed)
Perrin's beaked whale	Mesoplodon perrini Dalebout, Mead, Baker, Baker, & van Helding, 2002	DD IUCN	Unknown	(cetacean needed)	1.3–1.5 tonnes	(cetacean needed)
Pygmy beaked whale	Mesoplodon peruvianus Reyes, Mead, and Van Waerebeek, 1991	DD IUCN	Unknown		800 kg	(cetacean needed)
Sowerby's beaked whale	Mesoplodon bidens Sowerby, 1804	VU IUCN	Unknown		1-1.3 tonnes
Spade-toothed whale	Mesoplodon traversii, syn. Mesoplodon bahamondi Gray, 1874	DD IUCN	Unknown		1.2 tonnes	(cetacean needed)
Stejneger's beaked whale	Mesoplodon stejnegeri True, 1885	DD IUCN	Unknown		1.5 tonnes
Strap-toothed whale	Mesoplodon layardii Gray, 1865	DD IUCN	Unknown		2 tonnes
True's beaked whale	Mesoplodon mirus True, 1913	DD IUCN	Unknown		1.4 tonnes

Superfamily Platanistoidea: river dolphins

River dolphins are five species of dolphins which reside in freshwater rivers and estuaries. They are classed in the cetacean superfamily Platanistoidea. Four species live in fresh water rivers. The fifth species, the La Plata dolphin, lives in saltwater estuaries and the ocean. However, it is scientifically classed in the river dolphin family rather than the oceanic dolphin family. All species have adaptations to facilitate fish catching: a long, forceps-like beak with numerous small teeth in both jaws, broad flippers to allow tight turns, small eyes, and unfused neck vertebrae to allow the head to move in relation to the body.

Family Iniidae: river dolphins

This family contains one genus of two species, although the Amazon river dolphin (I. geoffrensis) has been divided into three subspecies:

• I. geoffrensis geoffrensis – Amazon basin population (excluding Madeira river drainage area, above the Teotonio Rapids in Bolivia)
• I. geoffrensis humboldtiana – Orinoco basin population
• Bolivian river dolphin – I. g. boliviensis – Amazon basin population in the Madeira drainage area

Genus Inia – two species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Amazon river dolphin	Inia geoffrensis Blainville, 1817	DD IUCN	Unknown		150 kg
Araguaian river dolphin	Inia araguaiaensis Hrbek, Da Silva, Dutra, Farias, 2014	NE	Unknown	Araguaian river dolphin in blue	150 kg

Family Lipotidae: baiji

The family Lipotidae is another monotypic taxon, containing only the baiji. Fossil records suggest the dolphin first appeared 25 million years ago and migrated from the Pacific Ocean to the Yangtze River 20 million years ago.^[20] The species was declared functionally extinct in 2006 after an expedition to record population numbers found no specimens.

Genus Lipotes – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
Baiji	Lipotes vexillifer Miller, 1918	CR IUCN	0-13 [lower-alpha 33]		130 kg

Family Platanistidae: South Asian river dolphin

The Platanistidae were originally thought to hold only one species (the South Asian river dolphin), but based on differences in skull structure, vertebrae and lipid composition, scientists declared the two populations as separate species in the early 1970s.^[21] In 1998, the results of these studies were questioned and the classification reverted to the pre-1970 consensus. Thus, at present, two subspecies are recognized in the genus Platanista, P. gangetica minor (the Indus dolphin) and P. g. gangetica (the Ganges river dolphin).^[22]

Genus Platanista – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
South Asian river dolphin	Platanista gangetica Roxburgh, 1801	EN IUCN	1,100 [lower-alpha 34]		200 kg

Family Pontoporiidae: La Plata river dolphin

The La Plata river dolphin is the only species of the family Pontoporiidae and genus Pontoporia.

Genus Pontoporia – one species
Common name	Scientific name	Status	Population	Distribution	Size	Picture
La Plata dolphin	Pontoporia blainvillei Gervais & d'Orbigny, 1844	VU IUCN	4,000–4,500		50 kg

See also

• List of marine mammal species
• List of whale vocalizations
• Evolution of cetaceans
• List of extinct cetaceans
• Archaeoceti
• Mammal classification

Footnotes

References

Further reading

External links

Wikimedia Commons has media related to Cetacea.

Wikispecies has information related to: Cetacea

The Wikibook Dichotomous Key has a page on the topic of: Cetacea

• Society for Marine Mammalogy's Taxonomy Committee List of Marine Mammal Species and subspecies
• CMS Small Cetaceans