Toothed whale

Toothed whales Fossil range: Latest Eocene - Recent
Bottlenose Dolphin
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Flower, 1869
Diversity
Around 73; see List of cetaceans or below.
Families
See text.

Cetaceans Portal

The toothed whales (systematic name Odontoceti) form a suborder of the cetaceans, including sperm whales, beaked whales, orca, dolphins, and others. As the name suggests, the suborder is characterized by having teeth, rather than baleen as do animals in the other suborder of cetaceans, Mysticeti. However, fossils indicate that early Baleen whales had teeth as well before evolving baleen, so defining the Odontoceti on teeth alone is problematic, and paleontologists have instead identified other features uniting fossil and modern odontocetes that are not shared by mysticetes. Toothed whales are active hunters, feeding on fish, squid, and in some cases marine mammals.

Baleen whales comprise the Mysticeti, one of two suborders of the mammalian order Cetacea, the other suborder being the Odontoceti, or toothed whales (dolphins, porpoises, and various whales). Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. They also differ from toothed whales in that they have two blowholes rather than one. Baleen whales also are known as whalebone whales or great whales.

Overview and description

Whales are members of the order Cetacea, which also includes dolphins and porpoises. Whales are the largest mammals, the largest vertebrates, and the largest known animals in the world. Like all mammals, whales breathe air into lungs, are warm-blooded, breast-feed their young, and have hair (although very little). Unlike fish, which breathe air using gills, whales breathe air through blowholes that lead into their lungs.

Cetaceans are divided into two suborders:

• The baleen whales (Mysticeti) are characterized by baleen, a sieve-like structure in the upper jaw made of the tough, structural protein keratin. The baleen is used to filter plankton from the water. Baleen whales are also characterized by two blowholes. Living Mysticeti species have teeth only during the embryonal phase. Fossil Mysticeti had teeth before baleen evolved.

• The toothed whales (Odontoceti) have teeth and prey on fish, squid, marine mammals, and so forth. This suborder includes dolphins and porpoises as well as whales. An outstanding ability of this group is to sense their surrounding environment through echolocation. Toothed whales have only one blowhole. In addition to numerous species of dolphins and porpoises, this suborder includes the Beluga whale and the sperm whale, which may be the largest toothed animals to ever inhabit Earth.

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.

Toothed whales, as all whales, develop as an embryo in the womb, they are then born as calves, grow into juveniles and finally become adults.

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 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.

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

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   * Suborder Odontoceti: toothed whales

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   * Family Delphinidae: oceanic dolphins

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   * Genus Cephalorhynchus
         o Commerson's Dolphin, Cephalorhynchus commersonii
         o Chilean Dolphin, Cephalorhynchus eutropia
         o Heaviside's Dolphin, Cephalorhynchus heavisidii
         o Hector's Dolphin, Cephalorhynchus hectori

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   * Genus Steno
         o Rough-toothed Dolphin, Steno bredanensis

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   * Genus Sousa
         o Atlantic Humpback Dolphin, Sousa teuszi
         o Indian Humpback Dolphin, Sousa plumbea
         o Chinese White Dolphin, Sousa chinensis

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   * Genus Sotalia
         o Tucuxi, Sotalia fluviatilis
         o Costero, Sotalia guianensis

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   * Genus Tursiops
         o Bottlenose Dolphin, Tursiops truncatus
         o Indian Ocean Bottlenose Dolphin, Tursiops aduncus

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   * Genus Stenella
         o Pantropical Spotted Dolphin, Stenella attenuata
         o Atlantic Spotted Dolphin, Stenella frontalis
         o Spinner Dolphin, Stenella longirostris
         o Clymene Dolphin, Stenella clymene
         o Striped Dolphin, Stenella coeruleoalba

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   * Genus Delphinus
         o Short-beaked Common Dolphin, Delphinus delphis
         o Long-beaked Common Dolphin, Delphinus capensis
         o (Arabian Common Dolphin, Delphinus tropicalis)

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   * Genus Lagenodelphis
         o Fraser's Dolphin, Lagenodelphis hosei

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   * Genus Lagenorhynchus
         o White-beaked Dolphin, Lagenorhynchus albirostris
         o Atlantic White-sided Dolphin, Lagenorhynchus acutus
         o Pacific White-sided Dolphin, Lagenorhynchus obliquidens
         o Dusky Dolphin, Lagenorhynchus obscurus
         o Black-chinned Dolphin, Lagenorhynchus australis
         o Hourglass Dolphin, Lagenorhynchus cruciger

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   * Genus Lissodelphis
         o Northern Right Whale Dolphin, Lissodelphis borealis
         o Southern Right Whale Dolphin, Lissodelphis peronii

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   * Genus Grampus
         o Risso's Dolphin, Grampus griseus

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   * Genus Peponocephala
         o Melon-headed Whale, Peponocephala electra

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   * Genus Feresa
         o Pygmy Killer Whale, Feresa attenuata

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   * Genus Pseudorca
         o False Killer Whale, Pseudorca crassidens

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   * Genus Orcinus
         o Orca (Killer Whale), Orcinus orca

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   * Genus Globicephala
         o Long-finned Pilot Whale, Globicephala melas
         o Short-finned Pilot Whale, Globicephala macrorhynchus

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   * Genus Orcaella
         o Irrawaddy Dolphin, Orcaella brevirostris
         o Australian Snubfin Dolphin, Orcaella heinsohni

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   * Family Monodontidae

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   * Genus Monodon
         o Narwhal, Monodon monoceros

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   * Genus Delphinapterus
         o Beluga, Delphinapterus leucas

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   * Family Phocoenidae: Porpoises

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   * Genus Neophocaena
         o Finless Porpoise, Neophocaena phocaenoides

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   * Genus Phocoena
         o Harbour Porpoise, Phocoena phocaena
         o Vaquita, Phocoena sinus
         o Spectacled Porpoise, Phocoena dioptrica
         o Burmeister's Porpoise, Phocoena spinipinnis

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   * Genus Phocoenoides
         o Dall's Porpoise, Phocoenoides dalli

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   * Family Physeteridae

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   * Genus Physeter
         o Sperm Whale, Physeter macrocephalus

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   * Family Kogiidae

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   * Genus Kogia
         o Dwarf Sperm Whale, Kogia sima
         o Pygmy Sperm Whale, Kogia breviceps

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   * Family Ziphidae: Beaked whales

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   * Genus Ziphius
         o Cuvier's Beaked Whale, Ziphius cavirostris

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   * Genus Berardius, giant beaked whales
         o Arnoux's Beaked Whale, Berardius arnuxii
         o Baird's Beaked Whale (North Pacific Bottlenose Whale), Berardius bairdii

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   * Genus Tasmacetus
         o Tasman Beaked Whale (Shepherd's Beaked Whale), Tasmacetus shepherdi

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   * Sub-family Hyperoodontidae

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   * Genus Indopacetus
         o Indo-Pacific Beaked Whale (Longman's Beaked Whale), Indopacetus pacificus

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   * Genus Hyperoodon
         o Northern Bottlenose Whale, Hyperoodon ampullatus
         o Southern Bottlenose Whale, Hyperoodon planifrons

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   * Genus Mesoplodon, mesoplodont whales
         o Hector's Beaked Whale, Mesoplodon hectori
         o True's Beaked Whale, Mesoplodon mirus
         o Gervais' Beaked Whale, Mesoplodon europaeus
         o Sowerby's Beaked Whale, Mesoplodon bidens
         o Gray's Beaked Whale, Mesoplodon grayi
         o Pygmy Beaked Whale, Mesoplodon peruvianus
         o Andrew's Beaked Whale, Mesoplodon bowdoini
         o Bahamonde's Beaked Whale, Mesoplodon bahamondi
         o Hubbs' Beaked Whale, Mesoplodon carlhubbsi
         o Ginko-toothed Beaked Whale, Mesoplodon ginkgodens
         o Stejneger's Beaked Whale, Mesoplodon stejnegeri
         o Layard's Beaked Whale, Mesoplodon layardii
         o Blainville's Beaked Whale, Mesoplodon densirostris
         o Perrin's Beaked Whale, Mesoplodon perrini

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   * Super-family Platanistoidea: river dolphins

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   * Family Iniidae

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   * Genus Inia
         o Amazon River Dolphin, Inia geoffrensis

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   * Family Lipotidae

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   * Genus Lipotes
         o Chinese River Dolphin, Lipotes vexillifer

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   * Family Platanistidae

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   * Genus Platanista
         o Ganges and Indus River Dolphin, Platanista gangetica

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   * Family Pontoporiidae

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   * Genus Pontoporia
         o La Plata Dolphin, Pontoporia blainvillei

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