Toothed whales

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	File:Bottlenose Dolphin KSC04pd0178.jpg
	Bottlenose Dolphin
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	See text.
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	Around 73; see List of cetaceans or below.

Animals · Animal ethology · Comparative psychology · Animal models · Outline · Index

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. The toothed whales (systematic name Odontoceti) form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.

Anatomy[]

Toothed whales have a single blowhole on the top of the head (while the baleen whales possess two of them).^[1] 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 cords 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[]

Vocalizations[]

Vocalizations are of great importance to toothed whales. While many species also maintain a broad variety of calls to communicate, all species investigated so far use short click sounds for purposes of echolocation. Sperm whales use low frequencies (a few to perhaps 50 Hz), while others 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.

Human impact[]

Small whales are beset by a variety of anthropogenic threats including hunting, bycatch (entanglement in fishing gear), competition with fisheries, ship strikes, tourism (whale watching and "dolphin-assisted" therapy), live capture for display and research, habitat loss and degradation, industrial and military operations, chemical pollution, disease and biotoxins (e.g., from dinoflagellates) ozone depletion and climate change.^[2]

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.

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.

Currently there is no international convention that gives universal coverage to all small whales, although the International Whaling Commission has attempted to extend its jurisdiction over them. ASCOBANS was negotiated to protect all small whales in the North and Baltic Seas and in the northeast Atlantic. ACCOBAMS protects all whales in the Mediterranean and Black Seas. The global UNEP Convention on Migratory Species currently covers seven toothed whale species or populations on its Appendix I and 37 species or populations on Appendix II. All whales (great and small) are listed in CITES Appendices, meaning that international trade in them and products derived from them is very limited.

Taxonomy[]

ORDER CETACEA
- Suborder Odontoceti: toothed whales
  - Superfamily Delphinoidea
    - Family Delphinidae: oceanic dolphins
      - Subfamily Delphininae
        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 Sousa
        Atlantic Humpback Dolphin, Sousa teuszi
        
        Indian Humpback Dolphin, Sousa plumbea
        
        Chinese White Dolphin, Sousa chinensis
        
        Genus Stenella (syn. Clymenia, Micropia, Fretidelphis, Prodelphinus)
        Pantropical Spotted Dolphin, Stenella attenuata
        
        Atlantic Spotted Dolphin, Stenella frontalis
        
        Spinner Dolphin, Stenella longirostris
        
        Clymene Dolphin, Stenella clymene
        
        Striped Dolphin, Stenella coeruleoalba
        
        Genus Tursiops
        Bottlenose Dolphin, Tursiops truncatus
        
        Indian Ocean Bottlenose Dolphin, Tursiops aduncus
      - Subfamily Lissodelphininae
        Genus Cephalorhynchus (syn. Eutropia)
        Commerson's Dolphin, Cephalorhynchus commersonii
        
        Chilean Dolphin, Cephalorhynchus eutropia
        
        Heaviside's Dolphin, Cephalorhynchus heavisidii
        
        Hector's Dolphin, Cephalorhynchus hectori
        
        Genus Lissodelphis (syn. Tursio, Leucorhamphus)
        Northern Right Whale Dolphin, Lissodelphis borealis
        
        Southern Right Whale Dolphin, Lissodelphis peronii
      - Subfamily Orcininae
        Genus Feresa
        Pygmy Killer Whale, Feresa attenuata
        
        Genus Globicephala (syn. Sphaerocephalus, Globiceps, Globicephalus)
        Long-finned Pilot Whale, Globicephala melas
        
        Short-finned Pilot Whale, Globicephala macrorhyncus
        
        Genus Grampus (syn. Grampidelphis, Grayius)
        Risso's Dolphin, Grampus griseus
        
        Genus Orcaella
        Irrawaddy Dolphin, Orcaella brevirostris
        
        Australian Snubfin Dolphin, Orcaella heinsohni
        
        Genus Orcinus (syn. Orca, Ophysia, Gladiator)
        Orca (Killer Whale), Orcinus orca
        
        Genus Peponocephala
        Melon-headed Whale, Peponocephala electra
        
        Genus †Platalearostrum (blunt-snouted dolphin)
        †Hoekman's Blunt-snouted Dolphin, Platalearostrum hoekmani
        
        Genus Pseudorca (syn. Neorca)
        False Killer Whale, Pseudorca crassidens
      - Subfamily Stenoninae
        Genus Sotalia (syn. Tucuxa)
        Tucuxi, Sotalia fluviatilis
        
        Costero, Sotalia guianensis
        
        Genus Steno (syn. Glyphidelphis, Stenopontistes)
        Rough-toothed Dolphin, Steno bredanensis
      - Subfamily incertae sedis
        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
    - Family Monodontidae
      - Subfamily Delphinapterinae
        Genus Delphinapterus
        Beluga whale, Delphinapterus leucas
      - Subfamily Monodontinae
        Genus Monodon
        Narwhal, Monodon monoceros
    - Family Phocoenidae: Porpoises
      - Subfamily Phocoeninae
        Genus Neophocaena (syn. Meomeris)
        Finless Porpoise, Neophocaena phocaenoides
        
        Genus Phocoena (syn. Australophocaena, Acanthodelphis)
        Harbour Porpoise, Phocoena phocaena
        
        Vaquita, Phocoena sinus
        
        Spectacled Porpoise, Phocoena dioptrica
        
        Burmeister's Porpoise, Phocoena spinipinnis
      - Subfamily Phocoenoidinae
        Genus Phocoenoides
        Dall's Porpoise, Phocoenoides dalli
  - Superfamily Inioidea
    - Family Iniidae
      - Genus Inia
        Bolivian River Dolphin, Inia boliviensis
        
        Amazon River Dolphin, Inia geoffrensis
    - Family Pontoporiidae
      - Genus Pontoporia
        La Plata Dolphin, Pontoporia blainvillei
  - Superfamily Lipotoidea
    - Family Lipotidae
      - Genus Lipotes
        Chinese River Dolphin, Lipotes vexillifer
  - Superfamily Physeteroidea
    - Family Kogiidae
      - Genus Kogia
        Dwarf Sperm Whale, Kogia sima
        
        Pygmy Sperm Whale, Kogia breviceps
    - Family Physeteridae: sperm whale family
      - Genus Physeter
        Sperm Whale, Physeter macrocephalus
  - Superfamily Platanistoidea: river dolphins
    - Family Platanistidae
      - Genus Platanista
        Ganges and Indus River Dolphin, Platanista gangetica
    - Family †Squalodontidae
      - Genus †Eosqualodon
      - Genus †Phoberodon
      - Genus †Squalodon (Jr synonyms Arionius, Crenidelphinus, Kelloggia, Macrophoca, Rhizoprion, Phoca pedronii, Phocodon, Priscodelphinus validus, Smilocamptus)
      - Genus †Tangaroasaurus
  - Superfamily Ziphioidea
    - Family Ziphidae, beaked whales
      - Subfamily Berardiinae
        Genus Berardius, giant beaked whales
        Arnoux's Beaked Whale, Berardius arnuxii
        
        Baird's Beaked Whale (North Pacific Bottlenose Whale), Berardius bairdii
      - Subfamily Hyperoodontinae
        Genus Hyperoodon
        Northern Bottlenose Whale, Hyperoodon ampullatus
        
        Southern Bottlenose Whale, Hyperoodon planifrons
        
        Genus Indopacetus
        Tropical bottlenose whale (Longman's Beaked Whale), Indopacetus pacificus
        
        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
        
        Andrews' 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
        
        Strap-toothed whale, Mesoplodon layardii
        
        Blainville's Beaked Whale, Mesoplodon densirostris
        
        Perrin's Beaked Whale, Mesoplodon perrini
      - Subfamily Ziphiinae
        Genus Tasmacetus
        Shepherd's beaked whale (Shepherd's Beaked Whale), Tasmacetus shepherdi
        
        Genus Ziphius
        Cuvier's Beaked Whale, Ziphius cavirostris

References[]

↑ Hooker, Sascha K. (2009). Encyclopedia of Marine Mammals, 2, 30 Corporate Drive, Burlington Ma. 01803: Academic Press.
↑ Reeves, R., B.D. Smith, E.A. Crespo, and G.N. di Sciara. 2003. Dolphins, Whales, and Porpoises. IUCN Species Survival Commission Specialists Group.

This page uses Creative Commons Licensed content from Wikipedia (view authors).

[emm-1] Hooker, Sascha K. (2009). Encyclopedia of Marine Mammals, 2, 30 Corporate Drive, Burlington Ma. 01803: Academic Press.

[2] Reeves, R., B.D. Smith, E.A. Crespo, and G.N. di Sciara. 2003. Dolphins, Whales, and Porpoises. IUCN Species Survival Commission Specialists Group.

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