Cetacea - Definition and Overview

Cetaceans

Humpback Whale breeching

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Cetacea

Suborders

Mysticeti
Odontoceti
(see text)

The order Cetacea includes whales, dolphins and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal," was more general. It comes from Greek ketos ("sea monster"). Cetology is the branch of marine science accociated with the study of cetaceans.

Cetaceans are the mammals most fully adapted to aquatic life. Their body is fusiform (spindle-shaped). The forelimbs are modified into flippers. The tiny hindlimbs are vestigial, they do not attach to the backbone and are hidden within the body. The tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber. Cetacea contains ten families, and about 80 species.

Contents

Evolution

Cetaceans are descendants of land-living mammals, most likely of the Artiodactyl order. They entered the water roughly 50 million years ago. See evolution of cetaceans for the details.

Taxonomic listing

The classification here closely follows "Marine Mammals of the World: Systematics and Distribution" by Dale W. Rice (1998). The work has become the standard taxonomy reference in the field. Differences reflect usage of common names and further discoveries since the publication of that work.

ORDER CETACEA
- Suborder Mysticeti: Baleen whales
  - Family Balaenidae: Right whales and Bowhead Whale
    - Genus Balaena
      - Bowhead Whale, Balaena mysticetus
    - Genus Eubalaena
      - Atlantic Northern Right Whale, Eubalaena glacialis
      - Pacific Northern Right Whale, Eubalaena japonica
      - Southern Right Whale, Eubalaena australia
  - Family Balaenopteridae: Rorquals
    - Subfamily Balaenopterinae
      - Genus Balaenoptera
        Fin Whale, Balaenoptera physalus
        Sei Whale, Balaenoptera borealis
        Bryde's Whale, Balaenoptera brydei
        Pygmy Bryde's Whale, (Eden's Whale) Balaenoptera edeni
        Blue Whale, Balaenoptera musculus
        Northern Minke Whale, Balaenoptera acutorostrata
        Southern Minke Whale, (Antarctic Minke Whale) Balaenoptera bonaerensis
        Balaenoptera omurai, discovery announced November 2003. No common name yet in usage
    - Subfamily Megapterinae
      - Genus Megaptera
        Humpback Whale, Megaptera novaeangliae
  - † Genus Eobalaenoptera
    - † Eobalaenoptera harrisoni, fossil species first discovered June 2004. No common name.
  - Family Eschrichtiidae
    - Genus Eschrichtius
      - Gray Whale, Eschrichtius robustus
  - Family Neobalaenidae: Pygmy Right Whale
    - Genus Caperea
      - Pygmy Right Whale, Caperea marginata
- Suborder Odontoceti: toothed whales
  - Superfamily Platanistoidea: River dolphins
    - Family Iniidae
      - Genus Inia
        Amazon River Dolphin, Inia geoffrensis
    - Family Lipotidae
      - Genus Lipotes
        Chinese River Dolphin, Lipotes vexillifer
    - Family Platanistidae
      - Genus Platanista
        Ganges and Indus River Dolphin, Platanista gangetica
    - Family Pontoporiidae
      - Genus Pontoporia
        La Plata Dolphin, Pontoporia blainvillei
  - Family Monodontidae
    - Genus Monodon
      - Narwhal, Monodon monocerus
    - Genus Delphinapterus
      - Beluga, Delphinapterus leucas
  - Family Phocoenidae: Porpoises
    - Genus Neophocaena
      - Finless Porpoise, Neophocaena phocaenoides
    - Genus Phocoena
      - Harbour Porpoise, Phocoena phocaena
      - Vaquita, Phocoena sinus
      - Spectacled Porpoise, Phocoena dioptrica
      - Burmeister's Porpoise, Phocoena spinipinnis
    - Genus Phocoenoides
      - Dall's Porpoise, Phocoenoides dalli
  - Family Physeteridae: Sperm Whale family
    - Genus Physeter
      - Sperm Whale, Physeter macrocephalus
  - Family Kogiidae
    - Genus Kogia
      - Dwarf Sperm Whale, Kogia sima
      - Pygmy Sperm Whale, Kogia breviceps
  - Family Ziphidae, Beaked whales
    - Genus Ziphius
      - Cuvier's Beaked Whale, Ziphius cavirostris
    - Genus Berardius
      - Arnoux's Beaked Whale, Berardius arnuxii
      - Baird's Beaked Whale (North Pacific Bottlenose Whale), Berardius bairdii
    - Genus Tasmacetus
      - Tasman Beaked Whale (Shepherd's Beaked Whale), Tasmacetus shepherdi
    - Subfamily Hyperoodontidae
      - Genus Indopacetus
        Indo-Pacific Beaked Whale (Longman's Beaked Whale), Indopacetus pacificus
      - Genus Hyperoodon
        Northern Bottlenose Whale, Hyperoodon ampullatus
        Southern Bottlenose Whale, Hyperoodon planifrons
      - Genus Mesoplodon, Mesoplodont Whale
        Hector's Beaked Whale, Mesoplodon hectori
        True's Beaked Whale, Mesoplodon mirus
        Gervais' Beaked Whale, Mesoplodon europaeus
        Sowerby's Beaked Whale, Mesoplodon bidens
        Gray's Beaked Whale, Mesoplodon grayi
        Pygmy Beaked Whale, Mesoplodon peruvianus
        Andrew's Beaked Whale, Mesoplodon bowdoini
        Bahamonde's Beaked Whale, Mesoplodon bahamondi
        Hubb's Beaked Whale, Mesoplodon carlhubbsi
        Ginko-toothed Beaked Whale, Mesoplodon ginkgodens
        Stejneger's Beaked Whale, Mesoplodon stejnegeri
        Layard's Beaked Whale, Mesoplodon layardii
        Blainville's Beaked Whale, Mesoplodon densirostris
  - Family Delphinidae: Dolphin
    - Genus Cephalorhynchus
      - Commerson's Dolphin, Cephalorhyncus commersonii
      - Chilean Dolphin, Cephalorhyncus eutropia
      - Heaviside's Dolphin, Cephalorhyncus heavisidii
      - Hector's Dolphin, Cephalorhyncus hectori
    - Genus Steno
      - Rough-toothed Dolphin, Steno bredanensis
    - Genus Sousa
      - Atlantic Humpback Dolphin, Sousa teuszi
      - Indian Humpback Dolphin, Sousa plumbea
      - Pacific Humpback Dolphin, Sousa chinensis
    - Genus Sotalia
      - Tucuxi, Sotalia fluviatilis
    - Genus Tursiops
      - Bottlenose Dolphin, Tursiops truncatus
      - Indian Ocean Bottlenose Dolphin, Tursiops aduncus
    - Genus Stenella
      - Pantropical Spotted Dolphin, Stenella attenuata
      - Atlantic Spotted Dolphin, Stenella frontalis
      - Spinner Dolphin, Stenella longirostris
      - Clymene Dolphin, Stenella clymene
      - Striped Dolphin, Stenella coeruleoalba
    - Genus Delphinus
      - Short-beaked Common Dolphin, Delphinus delphis
      - Long-beaked Common Dolphin, Delphinus capensis
      - (Arabian Common Dolphin, Delphinus tropicalis)
    - Genus Lagenodelphis
      - Fraser's Dolphin, Lagenodelphis hosei
    - Genus Lagenorhynchus
      - White-beaked Dolphin, Lagenorhynchus albirostris
      - Atlantic White-sided Dolphin, Lagenorhynchus acutus
      - Pacific White-sided Dolphin, Lagenorhynchus obliquidens
      - Dusky Dolphin, Lagenorhynchus obscurus
      - Black-chinned Dolphin, Lagenorhynchus australis
      - Hourglass Dolphin, Lagenorhynchus cruciger
    - Genus Lissodelphis
      - Northern Right Whale Dolphin, Lissodelphis borealis
      - Southern Right Whale Dolphin, Lissodelphis peronii
    - Genus Grampus
      - Risso's Dolphin, Grampus griseus
    - Genus Peponocephala
      - Melon-headed Whale, Peponocephala electra
    - Genus Feresa
      - Pygmy Killer Whale, Feresa attenuata
    - Genus Pseudorca
      - False Killer Whale, Pseudorca crassidens
    - Genus Orcinus
      - Orca, Orcinus orca
    - Genus Globicephala
      - Long-finned Pilot Whale, Globicephala melas
      - Short-finned Pilot Whale, Globicephala macrorhyncus
    - Genus Orcaella
      - Irrawaddy Dolphin, Orcaella brevirostris

References

Rice, Dale W. (1998). Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4. 231 pp. See the Society's website (http://www.marinemammalogy.org/publications.htm) for further details.

External links

American Cetacean Society (http://www.acsonline.org/)
British Cetacean Site (http://www.crru.org.uk/) especially interesting is taxonomy (http://www.crru.org.uk/education/factfiles/taxonomy.htm)
Cetacea.org homepage (http://www.cetacea.org/)
Walker's Mammals of the World Online - Cetaceans (http://www.press.jhu.edu/books/walkers_mammals_of_the_world/cetacea/cetacea.html#genera)
Tursiops.org: Current Cetacean-related news (http://www.tursiops.org/)

Mammals
Monotremata
Placentalia: Xenarthra \| Dermoptera \| Desmostylia \| Scandentia \| Primates \| Rodentia \| Lagomorpha \| Insectivora \| Chiroptera \| Pholidota \| Carnivora \| Perissodactyla \| Artiodactyla \| Cetacea \| Afrosoricida \| Macroscelidea \| Tubulidentata \| Hyracoidea \| Proboscidea \| Sirenia
Marsupialia: Didelphimorphia \| Paucituberculata \| Microbiotheria \| Dasyuromorphia \| Peramelemorphia \| Notoryctemorphia \| Diprotodontia

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