Whales are fully aquatic, open-ocean animals: they can feed, mate, give birth, suckle and raise their young at sea.

Whales evolved from land-living mammals, and must regularly surface to breathe air, although they can remain underwater for long periods of time.

With streamlined fusiform bodies and two limbs that are modified into flippers, whales can travel at speeds of up to 20 knots, though they are not as flexible or agile as seals.

Although whales are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres and migrate to the equator to give birth.

Small whales, such as belugas, are sometimes kept in captivity and trained to perform tricks, but breeding success has been poor and the animals often die within a few months of capture.

They feed by turning on their sides and taking in water mixed with sediment, which is then expelled through the baleen, leaving their prey trapped inside.

P. macrocephalus spends most of its life in search of squid in the depths; these animals do not require any degree of light at all, in fact, blind sperm whales have been caught in perfect health.

The behaviour of Kogiids remains largely unknown, but, due to their small lungs, they are thought to hunt in the photic zone.

[32][33][34] Whales have torpedo-shaped bodies with non-flexible necks, limbs modified into flippers, non-existent external ear flaps, a large tail fin, and flat heads (with the exception of monodontids and ziphiids).

The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility; whales are unable to turn their heads.

Whales swim by moving their tail fin and lower body up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering.

[45] The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater.

Whales do, however, lack short wavelength sensitive visual pigments in their cone cells indicating a more limited capacity for colour vision than most mammals.

Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass.

The southern right whale, for example, elevates their tail fluke above the water, remaining in the same position for a considerable amount of time.

Initially, moving organisms such as sharks and hagfish, scavenge the soft tissues at a rapid rate over a period of months, and as long as two years.

[86] Whales are typically hunted for their meat and blubber by aboriginal groups; they used baleen for baskets or roofing, and made tools and masks out of bones.

[87][88] 18th- and 19th-century whalers hunted whales mainly for their oil, which was used as lamp fuel and a lubricant, baleen or whalebone, which was used for items such as corsets and skirt hoops,[86] and ambergris, which was used as a fixative for perfumes.

[93] Current whaling nations are Norway, Iceland, and Japan, despite their joining to the IWC, as well as the aboriginal communities of Siberia, Alaska, and northern Canada.

This distinction is being questioned as these aboriginal groups are using more modern weaponry and mechanized transport to hunt with, and are selling whale products in the marketplace.

Some anthropologists argue that the term "subsistence" should also apply to these cash-based exchanges as long as they take place within local production and consumption.

[105] It is believed that up to two thirds of whale-ship collisions are not reported; either because they are not noticed in large ships, they occur at night or during conditions of adverse weather or some other reasons.

[108] Several species that were commercially exploited have rebounded in numbers; for example, grey whales may be as numerous as they were prior to harvesting, but the North Atlantic population is functionally extinct.

[120] Species that live in polar habitats are vulnerable to the effects of recent and ongoing climate change, particularly the time when pack ice forms and melts.

Whales played a major part in shaping the art forms of many coastal civilizations, such as the Norse, with some dating to the Stone Age.

[126] In coastal regions of China, Korea and Vietnam, the worship of whale gods, who were associated with Dragon Kings after the arrival of Buddhism, was present along with related legends.

They are so respected in their cultures that they occasionally hold funerals for beached whales, a custom deriving from Vietnam's ancient sea-based Champa Kingdom.

[136] In 1896, an article in The Pall Mall Gazette popularised a practice of alternative medicine that probably began in the whaling town of Eden, Australia two or three years earlier.

[142] Belugas are caught in the Amur River delta and their eastern coast, and then are either transported domestically to aquariums or dolphinariums in Moscow, St. Petersburg, and Sochi, or exported to other countries, such as Canada.

The latter is possible because while most cetacean "smiles" are fixed, the extra movement afforded by the beluga's unfused cervical vertebrae allows a greater range of apparent expression.