Cetacean (Dolphins,Whales)

Cetacean (Dolphins,Whales)

Cetaceans are members of the class Mammalia, commonly called mammals. The closest living relative of cetaceans is the hippopotamus.As mammals, cetaceans have characteristics that are common to all mammals: They are warm-blooded, breathe in air through their lungs, bear their young alive and suckle them on their own milk, and have hair, although very little of it.Another way of discerning a cetacean from a fish is by the shape of the tail. The tail of a fish is vertical and moves from side to side when the fish swims. The tail of a cetacean – called a fluke – is horizontal and moves up and down, as cetaceans’ spines bend in the same manner as a human spine.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 Ancient Greek κῆτος (kētos), “whale” or “any huge fish or sea monster.” Cetology is the branch of marine science associated 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. As a group, Cetaceans are noted for their high intelligence.The order Cetacea contains ninety species, all marine except for five species of freshwater dolphins. The order is divided into two suborders, Mysticeti (baleen whales) and Odontoceti (toothed whales, which includes dolphins and porpoises).The classification here closely follows Dale W. Rice, Marine Mammals of the World: Systematics and Distribution (1998), which has become the standard taxonomy reference in the field. There is very close agreement between this classification and that of Mammal Species of the World: 3rd Edition (Wilson and Reeder eds., 2005). Any differences are noted using the abbreviations “Rice” and “MSW3” respectively. Further differences due to recent discoveries are also noted. ORDER CETACEASuborder Mysticeti: Baleen whales Family Balaenidae: Right whales and Bowhead Whale Genus Balaena Bowhead Whale, Balaena mysticetus Genus Eubalaena North Atlantic Right Whale, Eubalaena glacialis North Pacific Right Whale, Eubalaena japonica Southern Right Whale, Eubalaena australis Family Balaenopteridae: Rorquals Subfamily Balaenopterinae Genus Balaenoptera Common Minke Whale, Balaenoptera acutorostrata Antarctic Minke Whale, Balaenoptera bonaerensis Sei Whale, Balaenoptera borealis Bryde’s Whale, Balaenoptera brydei Eden’s Whale Balaenoptera edeni – Rice lists this as a separate species, MSW3 does not Balaenoptera omurai – MSW3 lists this is a synonym of Bryde’s Whale but suggests this may be temporary. Blue Whale, Balaenoptera musculus Fin Whale, Balaenoptera physalus Subfamily Megapterinae Genus Megaptera Humpback Whale, Megaptera novaeangliae † Genus Eobalaenoptera † Harrison’s Whale, Eobalaenoptera harrisoni Family Eschrichtiidae Genus Eschrichtius Gray Whale, Eschrichtius robustus Family Neobalaenidae: Pygmy Right Whale Genus Caperea Pygmy Right Whale, Caperea marginata Suborder Odontoceti: toothed whales 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 Delphinus Long-beaked Common Dolphin, Delphinus capensis Short-beaked Common Dolphin, Delphinus delphis Arabian Common Dolphin, Delphinus tropicalis. Rice recognises this as a separate species. MSW3 does not. Genus Feresa Pygmy Killer Whale, Feresa attenuata Genus Globicephala Short-finned Pilot Whale, Globicephala macrorhyncus Long-finned Pilot Whale, Globicephala melas Genus Grampus Risso’s Dolphin, Grampus griseus Genus Lagenodelphis Fraser’s Dolphin, Lagenodelphis hosei Genus Lagenorhynchus Atlantic White-sided Dolphin, Lagenorhynchus acutus White-beaked Dolphin, Lagenorhynchus albirostris Peale’s Dolphin, Lagenorhynchus australis Hourglass Dolphin, Lagenorhynchus cruciger Pacific White-sided Dolphin, Lagenorhynchus obliquidens Dusky Dolphin, Lagenorhynchus obscurus Genus Lissodelphis Northern Right Whale Dolphin, Lissodelphis borealis Southern Right Whale Dolphin, Lissodelphis peronii Genus Orcaella Irrawaddy Dolphin, Orcaella brevirostris Australian Snubfin Dolphin, Orcaella heinsohni. 2005 discovery, thus not recognized by Rice or MSW3 and subject to revision. Genus Orcinus Killer Whale, Orcinus orca Genus Peponocephala Melon-headed Whale, Peponocephala electra Genus Pseudorca False Killer Whale, Pseudorca crassidens Genus Sotalia Tucuxi, Sotalia fluviatilis, but see the species article for a discussion Genus Sousa Pacific Humpback Dolphin, Sousa chinensis Indian Humpback Dolphin, Sousa plumbea Atlantic Humpback Dolphin, Sousa teuszii Genus Stenella Pantropical Spotted Dolphin, Stenella attenuata Clymene Dolphin, Stenella clymene Striped Dolphin, Stenella coeruleoalba Atlantic Spotted Dolphin, Stenella frontalis Spinner Dolphin, Stenella longirostris Genus Steno Rough-toothed Dolphin, Steno bredanensis Genus Tursiops – Rice and MSW3 tentatively agree on this classification but see species article for more detail. Indian Ocean Bottlenose Dolphin, Tursiops aduncus Common Bottlenose Dolphin, Tursiops truncatus Family Monodontidae Genus Delphinapterus Beluga, Delphinapterus leucas Genus Monodon Narwhal, Monodon monoceros Family Phocoenidae: Porpoises Genus Neophocaena Finless Porpoise, Neophocaena phocaenoides Genus Phocoena Spectacled Porpoise, Phocoena dioptrica Harbour Porpoise, Phocoena phocaena Vaquita, Phocoena sinus 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 – MSW3 treats Kogia as a member of Physeteridae Genus Kogia Pygmy Sperm Whale, Kogia breviceps Dwarf Sperm Whale, Kogia sima Superfamily Platanistoidea: River dolphins Family Iniidae Genus Inia Amazon River Dolphin, Inia geoffrensis Family Lipotidae – MSW3 treats Lipotes as a member of Iniidae Genus Lipotes † Baiji, Lipotes vexillifer Family Pontoporiidae – MSW3 treats Pontoporia as a member of Iniidae Genus Pontoporia Franciscana, Pontoporia blainvillei Family Platanistidae Genus Platanista Ganges and Indus River Dolphin, Platanista gangetica. MSW3 treats Platanista minor as a separate species, with common names Ganges River Dolphin and Indus River Dolphin, respectively. Family Ziphidae, Beaked whales Genus Berardius Arnoux’s Beaked Whale, Berardius arnuxii Baird’s Beaked Whale (North Pacific Bottlenose Whale), Berardius bairdii Subfamily Hyperoodontidae Genus Hyperoodon Northern Bottlenose Whale, Hyperoodon ampullatus Southern Bottlenose Whale, Hyperoodon planifrons Genus Indopacetus Indo-Pacific Beaked Whale (Longman’s Beaked Whale), Indopacetus pacificus Genus Mesoplodon, Mesoplodont Whale Sowerby’s Beaked Whale, Mesoplodon bidens Andrews’ Beaked Whale, Mesoplodon bowdoini Hubbs’ Beaked Whale, Mesoplodon carlhubbsi Blainville’s Beaked Whale, Mesoplodon densirostris Gervais’ Beaked Whale, Mesoplodon europaeus Ginkgo-toothed Beaked Whale, Mesoplodon ginkgodens Gray’s Beaked Whale, Mesoplodon grayi Hector’s Beaked Whale, Mesoplodon hectori Layard’s Beaked Whale, Mesoplodon layardii True’s Beaked Whale, Mesoplodon mirus Perrin’s Beaked Whale, Mesoplodon perrini. This species was recognised in 2002 and as such is listed by MSW3 but not Rice. Pygmy Beaked Whale, Mesoplodon peruvianus Stejneger’s Beaked Whale, Mesoplodon stejnegeri Spade Toothed Whale, Mesoplodon traversii Genus Tasmacetus Tasman Beaked Whale (Shepherd’s Beaked Whale), Tasmacetus shepherdi Genus Ziphius Cuvier’s Beaked Whale, Ziphius cavirostris †Extinct

Article Index:

Cetacean Taxonomy – Dolphins, Porpoises and Whales

KEYWORDS: dolphin taxonomy whale taxonomy porpoise taxonomy dolphin species whale species porpoise species baleen whales toothed whales

The terms “whales”, “dolphins”, and “porpoises”, are not scientific and have been used interchangeably throughout history. Usually the term “whale” is used to describe a large cetacean whereas smaller cetaceans are usually called dolphins or popoises. Porpoises however, should refer only to the six species belonging to the family Phocoenidae. To make matters worse, there is also a dolphin fish, better known as mahi-mahi or dorado.