Cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

is an

infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

that comprises the 94 species of

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...

s, and

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 an ...

s. It is divided into

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species of t ...

s (Odontoceti) and

baleen whale Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

s (Mysticeti), which diverged from each other in the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

some 50

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

(mya). Cetaceans are descended from land-dwelling hoofed mammals, and the now extinct

archaeocete Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean Evolutionary radiation, radiation, t ...

s represent the several transitional phases from terrestrial to completely aquatic. Historically, cetaceans were thought to have descended from the wolf-like

mesonychid Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. Mesonychids first appeared in the early Paleocene, went into a sharp decline at the end of the Eocene, and died out entirely ...

s, but

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analyses confirm their placement with

even-toed ungulate The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

s in the order Cetartiodactyla. Whale populations were drastically reduced in the 20th century from intensive

whaling Whaling is the process of hunting of whales for their usable products such as meat and blubber, which can be turned into a type of oil that became increasingly important in the Industrial Revolution. It was practiced as an organized industry ...

, and the activity was globally banned in 1982. Smaller cetaceans are at risk of accidentally getting caught by fishing vessels using, namely,

seine fishing Seine fishing (or seine-haul fishing; ) is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be dep ...

drift net Drift netting is a fishing technique where nets, called drift nets, hang vertically in the water column without being anchored to the bottom. The nets are kept vertical in the water by floats attached to a rope along the top of the net and weig ...

ting, or

gill net Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

ting operations.

Conventions

The following is a list of currently existing (or, in the jargon of taxonomy) '

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of the

cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

(for extinct cetacean species, see the

list of extinct cetaceans The list of extinct cetaceans features the extinct genera and species of the order Cetacea. The cetaceans (whales, dolphins and porpoises) are descendants of land-living mammals, the even-toed ungulates. The earliest cetaceans were still hoofe ...

). The list is organized

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

ally into

parvorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

s, superfamilies when applicable,

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

when applicable,

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

, and then species. In tabular form, seven descriptors are given for each species: the common name; the scientific name; the IUCN Red List status; a global population estimate; a global map with its range; its weight with an image of its shape, and its size relative to a

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

; and a photograph. Conservation status codes listed follow the

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

(v. 2014.3; data current at 20 January 2015). Where available, the global population estimate has been listed. When not cited or footnoted differently, these are from the

(v. 2014.3; data current at 20 January 2015).

Mysticeti: baleen whales

The baleen whales, also called whalebone whales or great whales, form the

Mysticeti. Baleen whales are characterized by having

baleen Baleen is a filter-feeding system inside the mouths of baleen whales. To use baleen, the whale first opens its mouth underwater to take in water. The whale then pushes the water out, and animals such as krill are filtered by the baleen and ...

plates for filter feeding and two blowholes.

Family Balaenidae: right whales

The family Balaenidae, the right whales, contains two genera and four species. All right whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ships * Ros ...

, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; and long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes.

Family Balaenopteridae: rorquals

Rorquals are the largest group of baleen whales, with eleven species in three genera. They include the largest animal that has ever lived, the

blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known to have ever existed. The blue whale's long and slender body can ...

. They take their name from a

Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe * Norwegians, both a nation and an ethnic group native to Norway * Demographics of Norway *The Norwegian language, including ...

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 The navel (clinically known as the umbilicus, commonly known as the belly button or tummy button) is a protruding, flat, or hollowed area on the abdomen at the attachment site of the umbilical cord. All placental mammals have a navel, although ...

(except the

sei whale The sei whale ( , ; ''Balaenoptera borealis'') is a baleen whale, the third-largest rorqual after the blue whale and the fin whale. It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar and tropical ...

, which has shorter grooves). They allow the mouth to expand immensely when feeding. All rorquals have these unique folds.

Family Cetotheriidae: pygmy right whale

The pygmy right whale shares several characteristics with the right whales, with the exception of having a dorsal fin. Also, 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. The pygmy right whale is the only extant member of its family.

Odontoceti: toothed whales

The toothed whales (parvorder Odontoceti), as the name suggests, are characterized by having teeth (rather than

). Toothed whales are active hunters, feeding on

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

, and in some cases other

marine mammal Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their reli ...

Family Delphinidae: oceanic dolphins

Oceanic dolphins are the members of the family Delphinidae. As the name implies, they tend to be found in the open seas, unlike the

river dolphin River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant riv ...

s, although a few species such as the

Irrawaddy dolphin The Irrawaddy dolphin (''Orcaella brevirostris'') is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the ...

are coastal or riverine. The Delphinidae are characterized by having distinct

beak The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...

s (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.

Family Iniidae: river dolphins

This family contains one genus with two species.

Family Kogiidae: dwarf and pygmy sperm whales

The dwarf and pygmy sperm whales resemble sperm whales, but are far smaller. 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.

Family Lipotidae: baiji

The family Lipotidae contains only the

baiji The baiji (; IPA: ; ''Lipotes vexillifer'', ''Lipotes'' meaning "left behind" and ''vexillifer'' "flag bearer") is a possibly extinct species of freshwater dolphin native to the Yangtze river system in China. It is thought to be the first dolph ...

. DNA evidence suggests it separated from oceanic dolphins about 25 million years ago. The species was declared

functionally extinct Functional extinction is the extinction of a species or other taxon such that: #It disappears from the fossil record, or historic reports of its existence cease; #The reduced population no longer plays a significant role in ecosystem function; or ...

in 2006 after an expedition to estimate the population found none.

Family Monodontidae: narwhal and 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 The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

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.

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 differences between the two groups are that porpoises have a less pronounced beak, and have spade-shaped teeth as opposed to conical. Porpoises, divided into seven species, live in all oceans. They span from species that live almost exclusively coastal and in rivers (

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 China, officially the People's Republic of China (PRC), is a country in East Asia. ...

s) to species that are entirely oceanic (

spectacled porpoise The spectacled porpoise (''Phocoena dioptrica'') is a small to midsize porpoise indigenous to the Southern Ocean. It is one of the most poorly studied cetaceans, partly due to its remote range in the southern ocean. What little is known about th ...

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.

Family Platanistidae: South Asian river dolphins

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, it was split into two separate species in the early 1970s, before being demoted back to subspecies in 1988. However, more recent studies support them being distinct species.

Family Pontoporiidae: La Plata dolphin

The La Plata dolphin is the only species of the family Pontoporiidae and genus ''Pontoporia''. These dolphins are known for their long beak in relation to their relatively small body size. They have a small geographic range and are mainly found in the waters along the east coast of South America. La Plata dolphins are exclusively marine organisms, however, they are grouped with river-dolphins due to the fact that they reside in the La Plata River which is a salt-water estuary. With their white or sometimes pale brown coloration, fishermen tend to call them "the white ghost", as they also tend to stray away from any human interaction.

Family Ziphiidae: beaked whales

A beaked whale is any of at least 22 species of whale in the family Ziphiidae. Several species have only been described in the last two decades. Six genera have been identified. They possess a unique feeding mechanism among cetaceans known as

suction feeding Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This problem was first identifi ...

. They 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 far backwards, three of four fused neck vertebrae, extensive skull asymmetry and two conspicuous throat grooves forming a 'V' pattern (which aid in sucking).

Footnotes

References

External links

CMS Small Cetaceans
{{DEFAULTSORT:List Of Cetaceans

Cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...