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A Sperm Whale fluke

Cetaceans (/sɪˈtʃəns/) (from Latin: cetus, lit. 'whale', from Ancient Greek: κῆτος, romanizedkētos, lit. 'huge fish') are aquatic mammals constituting the infraorder Cetacea. There are around 89 living species, which are divided into two parvorders. The first is the Odontoceti, the toothed whales, which consist of around 70 species, including the dolphin (which includes killer whales), porpoise, beluga whale, narwhal, sperm whale, and beaked whale. The second is the Mysticeti, the baleen (from Latin: balæna, lit. 'whale') whales, which have a filter-feeder system, and consist of 15 species divided into 3 families, and include the right whale, bowhead whale, rorqual, pygmy right whale, and gray whale.

The ancient and extinct ancestors of modern whales (Archaeoceti) lived 53 to 45 million years ago. They diverged from even-toed ungulates; their closest living relatives are hippopotamuses and others such as camels and pigs. They were amphibious, and evolved in the shallow waters that separated India from Asia. Around 30 species adapted to a fully oceanic life. Baleen whales split from toothed whales around 34 million years ago.

The smallest cetacean is Maui's dolphin, at 1 m (3 ft 3 in) and 50 kg (110 lb); the largest is the blue whale, at 29.9 m (98 ft) and 173 t (381,000 lb). Baleen whales have a tactile system in the short hairs (vibrissae) around their mouth; toothed whales do not have vibrissae. Cetaceans have well-developed senses—their eyesight and hearing are adapted for both air and water. They have a layer of fat, or blubber, under the skin to maintain body heat in cold water. Several species exhibit sexual dimorphism. Two external forelimbs are modified into flippers; two internal hindlimbs are vestigial. Cetaceans have streamlined bodies: they can swim very quickly, with the killer whale able to travel at 56 kilometres per hour (35 mph) in short bursts, the fin whale able to cruise at 48 kilometres per hour (30 mph), dolphins able to make very tight turns at high speeds, and some species diving to great depths.

Although cetaceans are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres. They spend their lives in the water of seas and rivers; having to mate, give birth, molt or escape from predators, like killer whales, underwater. This has drastically affected their anatomy to be able to do so. They feed largely on fish and marine invertebrates; but a few, like the killer whale, feed on large mammals and birds, such as penguins and seals. Some baleen whales (mainly gray whales and right whales) are specialised for feeding on benthic creatures. Male cetaceans typically mate with more than one female (polygyny), although the degree of polygyny varies with the species. Cetaceans are not known to have pair bonds. Male cetacean strategies for reproductive success vary between herding females, defending potential mates from other males, or whale song which attracts mates. Calves are typically born in the fall and winter months, and females bear almost all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively short period of time, which is more typical of baleen whales as their main food source (invertebrates) aren't found in their breeding and calving grounds (tropics). Cetaceans produce a number of vocalizations, notably the clicks and whistles of dolphins and the moaning songs of the humpback whale. Read more...

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The crew of the oceanographic research vessel "Princesse Alice," of Albert Grimaldi (later Prince Albert I of Monaco) pose while flensing a catch.

Whaling is the harvesting of free-roaming whales from the oceans and dates back to at least 6,000 BC. Whaling and other threats have led to at least 5 of the 13 great whales being listed as endangered. Commercial whaling is subject to a moratorium by the International Whaling Commission (IWC), however, at the 2006 IWC meeting, the St Kitts and Nevis Declaration, which protests the moratorium, was adopted by a slim majority.

It is unknown when humans began hunting whales. The earliest archaeological record of whaling is found in South Korea where carved drawings, dating back to 6,000 BC, show that Stone Age people hunted whales using boats and spears. However, over time, whaling techniques have grown more technologically sophisticated. Initially, whaling was confined to (near) coastal waters, such as the Basque fishery targeting the North Atlantic Right Whale from the 11th to 18th century and the Atlantic Arctic fishery around and in between Spitsbergen and Greenland from the 17th to the 20th century. However, after the emergence of modern whaling techniques, certain species of whale started to be seriously affected by whaling. These techniques were spurred in the 19th century by the increase in demand for whale oil, and later in the 20th century by a demand for whale meat.

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Humpback Whale fluke
Photo credit: Captain Budd Christman of the NOAA.

The Humpback Whale (Megaptera novaeangliae) is a mammal which belongs to the baleen whale suborder. It is a large whale: an adult usually ranges between 12–16 m (40–50 ft) long and weighs approximately 36,000 kilograms (79,000 lb). It is well known for its breaching (leaping out of the water), its unusually long front fins, and its complex whale song. The Humpback Whale lives in oceans and seas around the world, and is regularly sought out by whale-watchers.

Did you know...

  • ...when right whales and humpback whales breach (leap out of the water), seagulls can often be seen darting in to pick up pieces of skin that become dislodged from the breaching whales. Presumably this is an easy source of food for seagulls.
  • ...whales and dolphins don’t sleep in the way humans do. Although we don’t know how they sleep, some scientists believe they sleep with half the brain asleep and half the brain awake, keeping them aware of danger.
  • ...all whales and dolphins have the remains of the pelvis, but it is reduced to two small bones at the rear of the animal.
  • ...the ‘strapped-toothed whale’ is so called because in mature males there are only two teeth in the bottom jaw and these completely ‘strap’ the upper jaw, preventing it from opening more than a few centimetres. How these animals eat is unknown, but it may be that they stun their prey with high intensity sound.
  • ...some cetaceans can dive to depths of more than a kilometre and stay there for more than an hour.

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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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Cetaceans News

2014

January

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]

2009

February

  • 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

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2008

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