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| 질의: Sperm whale | 결과: 65번째/133 | |
Toothed Whale (Order: Cetacea, Suborder: Odontoceti) - Wiki
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Toothed whale
From Wikipedia, the free encyclopedia
[Photo] A dolphin surfs the wake of a research boat on the Banana River'' - near the Kennedy Space Center. Espa??ol: Delf??n nariz de botella (Bottlenose Dolphin - Tursiops truncatus). Source: http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=21807
The toothed whales (systematic name Odontoceti) form a suborder of the cetaceans. As the name suggests, the suborder is characterized by having teeth (rather than baleen as do animals in the other suborder of cetaceans, Mysticeti). Toothed whales are active hunters, feeding on fish, squid, and in some cases marine mammals.
Anatomy
Toothed whales have a single blowhole on the top of the head (while the baleen whales possess two of them). The nostrils are not fused; one of them has become dominant over the other.
As an adaptation for their echolocation, toothed whale skulls have become asymmetric. Their brains are relatively big, although real growth didn't occur before their echolocation started to evolve. Toothed whales' brains have a poor connection between the two hemispheres and an organ called a melon on their heads is used as a lens to focus sound waves. Vocal chords are not present; their sounds are produced in the blowhole system instead. Toothed whales have lost their sense of smell, as well as their saliva glands.
Except for the Sperm Whale, most toothed whales are smaller than the baleen whales. The teeth differ considerably between the species. They may be numerous, with some dolphins bearing over 100 teeth in their jaws. At the other extreme are the Narwhal with its single long tusk and the almost toothless beaked whales with bizarre teeth only in males. Not all species are believed to use their teeth for feeding. For instance, the Sperm Whale likely uses its teeth for aggression and showmanship.
Behaviour
Vocals
Vocalizations are of great importance for toothed whales. While many species also maintain a broad variety of calls to communicate; all species investigated so far use short click sound for purposes of echolocation. Sperm whales use low frequencies (a few to perhaps 50 kHz), while other employ more narrow band high frequency sounds (porpoises, Cephalorhynchus species like Hector's dolphin). Most dolphin species use very broad band clicks.
Movement
Most toothed whales swim rapidly. The smaller species occasionally ride waves, such as the bow waves of ships. Dolphins can be frequently encountered this way. They are also famous for their acrobatic breaching from the water, e.g. the Spinner Dolphin.
Social behaviour
Generally, toothed whales live in groups of up to a dozen animals. These groups, called pods or schools, occasionally merge to form "superpods", aggregations of up to thousands of whales. Toothed whales are capable of complex interactions, such as cooperative hunting. In captivity, some species display a high potential for learning; for this reason they are considered being among the most intelligent animals.
Human impact
The Sperm Whale has been hunted commercially for a long time (see whaling). While small whales like the Pilot Whale today are still being pursued, the main threat for most species is accidental capture in fishing nets.
Keeping small whales (mostly Bottlenose Dolphins, Orcas, or Belugas) in captivity is a great attraction for ocean parks and zoos. However, it is controversial because of the marine mammals' need for large spaces.
Taxonomy
ORDER CETACEA
Suborder Odontoceti: toothed whales
Family Delphinidae: oceanic dolphins
Genus Cephalorhynchus
Commerson's Dolphin, Cephalorhynchus commersonii'
Chilean Dolphin, Cephalorhynchus eutropia
Heaviside's Dolphin, Cephalorhynchus heavisidii'
Hector's Dolphin, Cephalorhynchus hectori
Genus Steno
Rough-toothed Dolphin, Steno bredanensis
Genus Sousa
Atlantic Humpback Dolphin, Sousa teuszi
Indian Humpback Dolphin, Sousa plumbea
Chinese White 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 (Killer Whale), Orcinus orca
Genus Globicephala
Long-finned Pilot Whale, Globicephala melas
Short-finned Pilot Whale, Globicephala macrorhynchus
Genus Orcaella
Irrawaddy Dolphin, Orcaella brevirostris
Australian Snubfin Dolphin, Orcaella heinsohni
Family Monodontidae
Genus Monodon
Narwhal, Monodon monoceros
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
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, giant beaked whales
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
Sub-family 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 whales
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
Hubbs' 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
Perrin's Beaked Whale, Mesoplodon perrini
Super-family 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
http://en.wikipedia.org/wiki/Toothed_whale
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