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The Cetaceans portal

A Sperm Whale fluke

Cetacea (/sɪˈtʃə/) is a widely distributed and diverse clade of aquatic mammals that today consists of whales, dolphins, and porpoises. Cetaceans are carnivorous and finned. Most species live in the sea, some in rivers. The name is derived from the Latin cetus "whale", itself from the Greek κῆτος kētos "huge fish".

There are around 89 extant species, which are divided into two groups or parvorders, the Odontoceti or toothed whales, a group of more than 70 species that includes the dolphins, porpoises, belugas, narwhals, sperm and beaked whales, and the Mysticeti or baleen whales, of which there are now 15 species. The extinct ancestors of modern whales are the Archaeoceti.

While cetaceans were historically thought to have descended from mesonychids, molecular evidence supports them as a relative of Artiodactyls (even-toed ungulates). Cetaceans belong to the order Cetartiodactyla (formed by combining Cetacea + Artiodactyla) and their closest living relatives are hippopotamuses and other hoofed mammals (camels, pigs, and ruminants), having diverged about 50 million years ago.

Cetaceans range in size from the 1 m (3 ft 3 in) and 50 kg (110 lb) Maui's dolphin to the 29.9 m (98 ft) and 173,000 kg (381,000 lb) blue whale, which is also the largest animal ever known to have existed. Several species exhibit sexual dimorphism. They have streamlined bodies and two (external) limbs that are modified into flippers. Though not as flexible or agile as seals, cetaceans can swim very quickly, with the killer whale able to travel at 56 kilometres per hour (35 mph) in short bursts and the fin whale able to cruise at 48 kilometres per hour (30 mph). Dolphins are able to make very tight turns while swimming at high speeds. The hindlimbs of cetaceans are internal, and are thought to be vestigial. Baleen whales have short hairs on their mouth, unlike the toothed whales. Cetaceans have well-developed senses—their eyesight and hearing are adapted for both air and water, and baleen whales have a tactile system in their vibrissae. They have a layer of fat, or blubber, under the skin to maintain body heat in cold water. Some species are well adapted for diving to great depths. Read more...

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Whale watching off the coast of Bar Harbor, Maine.
Whale watching is the practice of observing whales and other cetaceans in their natural habitat. Whales are watched most commonly for recreation (cf. bird watching) but the activity can also be for scientific or educational reasons. Whilst individuals do organize private trips, whale watching is primarily a commercial activity, estimated to be worth up to $1billion per annum worldwide to whale watching operations and their local communities. The size and rapid growth of the whale watching industry has led to complex and unconcluded debates with the whaling industry about the best use of whales as a natural resource.

Whale watching as an organized activity dates back to 1950 when the Cabrillo National Monument in San Diego was declared a public spot for the observation of Gray Whales. In 1955 the first water-based whale watching commenced in the same area, charging customers $1 per trip to view the whales at closer quarters. The spectacle proved popular, attracting 10,000 visitors in its first year and many more in subsequent years. The industry spread throughout the western coast of the United States over the following decade.

Whale watching today is carried out from the water from crafts from kayaks, motorized rafts, and sailboats through to out-of-use fish or whaling boats and custom-built craft carrying as many as 400 people. Land-based watching of species such as the Orca who come very close to shore remains popular. Viewing of species that usually stay some distance from the shore is also offered by fixed-wing aircraft or helicopters in some areas.

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Cetaceans News



The clymene dolphin (Stenella clymene) became the first confirmed naturally occurring hybrid marine mammal species when DNA analysis showed it to be descended from the spinner dolphin and the striped dolphin. [1]



  • 10 February - Filipino fishermen have rescued around 200 melon-headed whales which were stranded in shallow waters off the coast of Bataan. Only three dolphins were reported to have died. more





Did you know...

A Bottlenose Dolphin Breaching the water
  • ...dolphins often leap clear of the water when travelling at speed. This is because the density of water is much greater than that of air and they are able to travel faster by leaping out of the water.
  • ...whale and dolphin mothers ‘suckle’ their young underwater! Mothers have muscular mammary glands and ‘squirt’ their milk into the calf’s mouth, to ensure that the calf takes in as much of the energy rich milk as possible.
  • ...on average, a whale or dolphin will eat four to five percent of its body weight in food per day. That means that a 100 ton blue whale will eat almost five tons of krill per day, or that a 200kg bottlenose dolphin will eat 10kg of fish per day!
  • ...newborn cetacean calves ‘suckle’ three to four times each hour and will suckle from their mothers for six months or more.


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A pair of humpback whales lung-feeding.
Photo credit: U.S Government's Minerals Management Service

Humpback Whales blow a curtain of bubbles around their prey and then lunge through them with their mouths open. The Humpbacks strain the tiny creatures, called krill, through the baleen in their mouths.

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The content you are reading was created by Wikipedia volunteers. See the WikiProject Cetaceans for more.

Related WikiProjects include:

See also Wikispecies, a Wikimedia project dedicated to the classification of species.

Cetacean articles

Whale species

Andrews' Beaked WhaleBalaenoptera omuraiBelugaBlainville's Beaked WhaleBlue Whale Cscr-featured.svgBottlenose WhaleBowhead WhaleBryde's WhaleCuvier's Beaked WhaleDwarf Sperm WhaleFin Whale Cscr-featured.svgGervais' Beaked WhaleGiant beaked whaleGinkgo-toothed Beaked WhaleGray WhaleGray's Beaked WhaleHector's Beaked WhaleHubbs' Beaked WhaleHumpback Whale Cscr-featured.svgLayard's Beaked WhaleLongman's Beaked WhaleMelon-headed WhaleMinke WhaleNarwhalPerrin's Beaked WhalePygmy Beaked WhalePygmy Killer WhalePygmy Right WhalePygmy Sperm WhaleRight Whale Cscr-featured.svgSei Whale Cscr-featured.svgShepherd's Beaked WhaleSowerby's Beaked WhaleSpade Toothed WhaleSperm Whale Symbol support vote.svgStejneger's Beaked WhaleTrue's Beaked Whale

Dolphin species

Atlantic Spotted DolphinAtlantic White-sided DolphinAustralian Snubfin DolphinBaijiBotoChilean DolphinClymene DolphinCommerson's DolphinCommon Bottlenose DolphinDusky Dolphin Symbol support vote.svgFalse Killer WhaleFraser's DolphinGanges and Indus River DolphinHeaviside's DolphinHector's DolphinHourglass DolphinHumpback dolphinIndo-Pacific Bottlenose DolphinIrrawaddy DolphinKiller Whale Cscr-featured.svgLa Plata DolphinLong-beaked Common DolphinLong-finned pilot whalePacific White-sided DolphinPantropical Spotted DolphinPeale's DolphinPygmy Killer WhaleRight whale dolphinRisso's DolphinRough-toothed DolphinShort-beaked Common DolphinShort-finned pilot whaleSpinner DolphinStriped DolphinTucuxiWhite-beaked Dolphin

Porpoise species

Burmeister's PorpoiseDall's PorpoiseFinless PorpoiseHarbour PorpoiseSpectacled PorpoiseVaquita

Other articles

Aboriginal whalingAmbergrisAnimal echolocationArchaeocetiBaleenBaleen whaleBeached whaleBeaked WhaleBlowhole (biology)BlubberBottlenose dolphin Symbol support vote.svgCallosityCephalorhynchusCetaceaCetacean intelligenceCetologyCetology of Moby-DickCommon dolphinCumberland Sound BelugaDolphinDolphinarium Symbol support vote.svgDolphin drive hunting Symbol support vote.svgEvolution of cetaceansExploding whaleHarpoonHistory of whalingHuman–animal communicationInstitute of Cetacean ResearchInternational Whaling CommissionLagenorhynchusMelon (whale)Mesoplodont WhaleMilitary dolphinMoby-DickMocha DickMonodontidaeOceanic dolphinOrcaellaPilot Whale Symbol support vote.svgPorpoiseRiver dolphinRiver Thames WhaleRorqualsSperm whale familySperm whalingSpermacetiStenellaTay WhaleThe Marine Mammal CenterToothed WhaleU.S. Navy Marine Mammal ProgramWhale Symbol support vote.svgWhalingWhale and Dolphin Conservation SocietyWhale surfacing behaviourWhale oilWhale louseWhale songWhale watchingWolphin

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