55-446: The Australian Whale Sanctuary, established in 1999, aims to protect dolphins and whales from hunting in waters within the Australian government's jurisdiction . The sanctuary encompasses the entire Australian Exclusive Economic Zone (EEZ), extending 200 nautical miles (370 km) surrounding the continent of Australia and its external dependencies such as Christmas Island (in
110-415: A pinna and hair . Whales have an elongated head, especially baleen whales , due to the wide overhanging jaw. Bowhead whale plates can be 9 metres (30 ft) long. Their nostril(s) make up the blowhole , with one in toothed whales and two in baleen whales. The nostrils are located on top of the head above the eyes so that the rest of the body can remain submerged while surfacing for air. The back of
165-601: A factor in the ability to produce sounds used in echolocation. Mysticeti, who don't have the ability to echolocate, possess general symmetry of the skull and facial region, while Odontoceti display a nasofacial asymmetry that is linked to their echolocating abilities. Differences in the level of asymmetry also seem to correlate with differences in the types of sounds produced. Mysticeti have exceptionally thin, wide basilar membranes in their cochleae without stiffening agents, making their ears adapted for processing low to infrasonic frequencies. The initial karyotype includes
220-439: A large melon and multiple, asymmetric air bags. River dolphins , unlike most other cetaceans, can turn their head 90°. Most other cetaceans have fused neck vertebrae and are unable to turn their head at all. The baleen of baleen whales consists of long, fibrous strands of keratin. Located in place of the teeth, it has the appearance of a huge fringe and is used to sieve the water for plankton and krill. Sperm whales have
275-580: A latitudinal basis to move between seasonal habitats. For example, the gray whale migrates 10,000 miles (16,000 km) round trip. The journey begins at winter birthing grounds in warm lagoons along Baja California, and traverses 5,000–7,000 miles (8,000–11,300 km) of coastline to summer feeding grounds in the Bering, Chuckchi and Beaufort seas off the coast of Alaska. Conscious breathing cetaceans sleep but cannot afford to be unconscious for long, because they may drown. While knowledge of sleep in wild cetaceans
330-537: A set of chromosomes from 2n = 44. They have four pairs of telocentric chromosomes (whose centromeres sit at one of the telomeres ), two to four pairs of subtelocentric and one or two large pairs of submetacentric chromosomes. The remaining chromosomes are metacentric—the centromere is approximately in the middle—and are rather small. All cetaceans have chromosomes 2n = 44, except the sperm whales and pygmy sperm whales , which have 2n = 42. Cetaceans are found in many aquatic habitats. While many marine species, such as
385-725: A specific body of water. The southern right whale dolphin and the hourglass dolphin live only in the Southern Ocean . The narwhal and the beluga live only in the Arctic Ocean. Sowerby's beaked whale and the Clymene dolphin exist only in the Atlantic and the Pacific white-sided dolphin and the northern straight dolphin live only in the North Pacific. Cosmopolitan species may be found in
440-426: A terrestrial mammal breathing out on a cold day, a small cloud of 'steam' appears. This is called the 'spout' and varies across species in shape, angle and height. Species can be identified at a distance using this characteristic. The structure of the respiratory and circulatory systems is of particular importance for the life of marine mammals . The oxygen balance is effective. Each breath can replace up to 90% of
495-654: Is bicornuate . Cetacean eyes are set on the sides rather than the front of the head. This means only species with pointed 'beaks' (such as dolphins) have good binocular vision forward and downward. Tear glands secrete greasy tears, which protect the eyes from the salt in the water. The lens is almost spherical, which is most efficient at focusing the minimal light that reaches deep water. Odontocetes have little to no ability to taste or smell, while mysticetes are believed to have some ability to smell because of their reduced, but functional olfactory system . Cetaceans are known to possess excellent hearing. At least one species,
550-447: Is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales , dolphins and porpoises . Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver. While
605-515: Is considered to be functionally extinct due to human activity. The two parvorders, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have diverged around thirty-four million years ago. Baleen whales have bristles made of keratin instead of teeth . The bristles filter krill and other small invertebrates from seawater. Grey whales feed on bottom-dwelling mollusks. Rorqual family (balaenopterids) use throat pleats to expand their mouths to take in food and sieve out
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#1732848830292660-430: Is home to elongated spindle neurons that, prior to 2019, were known only in hominids . In humans, these cells are thought to be involved in social conduct, emotions, judgment and theory of mind. Cetacean spindle neurons are found in areas of the brain homologous to where they are found in humans, suggesting they perform a similar function. The cetacean skeleton is largely made up of cortical bone , which stabilizes
715-433: Is limited, toothed cetaceans in captivity have been recorded to exhibit unihemispheric slow-wave sleep (USWS), which means they sleep with one side of their brain at a time, so that they may swim, breathe consciously and avoid both predators and social contact during their period of rest. A 2008 study found that sperm whales sleep in vertical postures just under the surface in passive shallow 'drift-dives', generally during
770-451: Is more vascularized—rich in blood vessels —than other adipose tissue. Blubber has advantages over fur (as in sea otters ) in that, though fur retains heat by holding pockets of air, the air expels under pressure (i.e., when the animal dives). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as 4 °C (40 °F). While diving in cold water, blood vessels covering
825-415: Is not indicative of larger whales' ability to retain heat better, as the thickness of a whale's blubber does not significantly affect heat loss. More indicative of a whale's ability to retain heat is the water and lipid concentration in blubber, as water reduces heat-retaining capacities, and lipid increases them. Blubber is the primary fat storage on some mammals , specifically those that live in water. It
880-435: Is particularly important for species that feed and breed in different parts of the ocean. During these periods, the animals metabolize fat. Blubber may save energy for marine mammals, such as dolphins, in that it adds buoyancy while swimming . Blubber differs from other forms of adipose tissue in its extra thickness, which provides an efficient thermal insulator , making blubber essential for thermoregulation . Blubber
935-424: Is so well-adapted for both air and water that some blind specimens can survive. Some species, such as sperm whales, are well adapted for diving to great depths. Several species of toothed whales show sexual dimorphism , in which the males differ from the females, usually for purposes of sexual display or aggression. Cetacean bodies are generally similar to those of fish, which can be attributed to their lifestyle and
990-759: Is swallowed whole. Teeth are shaped like cones (dolphins and sperm whales), spades ( porpoises ), pegs ( belugas ), tusks ( narwhals ) or variable (beaked whale males). Female beaked whales' teeth are hidden in the gums and are not visible, and most male beaked whales have only two short tusks. Narwhals have vestigial teeth other than their tusk, which is present on males and 15% of females and has millions of nerves to sense water temperature, pressure and salinity. A few toothed whales, such as some orcas , feed on mammals, such as pinnipeds and other whales. Toothed whales have well-developed senses – their eyesight and hearing are adapted for both air and water, and they have advanced sonar capabilities using their melon . Their hearing
1045-412: Is vital for deep diving, since beyond a depth around 100 m (330 ft), the lung tissue is almost completely compressed by the water pressure. The stomach consists of three chambers. The first region is formed by a loose gland and a muscular forestomach (missing in beaked whales); this is followed by the main stomach and the pylorus . Both are equipped with glands to help digestion. A bowel adjoins
1100-455: The Amazon river dolphin . The collarbone is completely absent. Cetaceans have a cartilaginous fluke at the end of their tails that is used for propulsion. The fluke is set horizontally on the body and used with vertical movements, unlike fish and ichthyosaurs, which have vertical tails which move horizontally. Cetaceans have powerful hearts. Blood oxygen is distributed effectively throughout
1155-626: The Federal Court of Australia ruled it was illegal under Australian law for the Japanese whaling fleet to kill whales in the Sanctuary. In 2015 Kyodo Senpaku Kaisha Ltd was found guilty of wilful contempt of court and fined A$ 1,000,000. Cetacean ( see text for families) Cetacea ( / s ɪ ˈ t eɪ ʃ ə / ; from Latin cetus ' whale ', from Ancient Greek κῆτος ( kêtos ) ' huge fish , sea monster ')
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#17328488302921210-637: The Indian Ocean ), Cocos (Keeling) Island , Norfolk Island , Macquarie Island and Heard Island and McDonald Islands . Additionally, it includes the EEZ adjacent to the coastline of the Australian Antarctic Territory , recognised only by the United Kingdom , New Zealand , France and Norway . The sanctuary is the scene of an ongoing controversy between Australia and Japan over whaling. In 2008
1265-514: The Inuktitut language) is an important part of the traditional diets of the Inuit and of other northern peoples, because of its high energy value and availability. Whale blubber, which tastes like arrowroot biscuits, has similar properties. Whaling largely targeted the collection of blubber: whalers rendered it into oil in try pots , or later, in vats on factory ships . The oil could serve in
1320-532: The beaked whale family, several species of the porpoise family, orcas, pilot whales , eastern spinner dolphins and northern right whale dolphins show this characteristic. Males in these species developed external features absent in females that are advantageous in combat or display. For example, male sperm whales are up to 63% percent larger than females, and many beaked whales possess tusks used in competition among males. Hind legs are not present in cetaceans, nor are any other external body attachments such as
1375-654: The blue whale , the humpback whale and the orca , have a distribution area that includes nearly the entire ocean, some species occur only locally or in broken populations. These include the vaquita , which inhabits a small part of the Gulf of California and Hector's dolphin , which lives in some coastal waters in New Zealand. Most river dolphin species live exclusively in fresh water. Many species inhabit specific latitudes, often in tropical or subtropical waters, such as Bryde's whale or Risso's dolphin . Others are found only in
1430-512: The hypodermis and covers the whole body, except for parts of the appendages. It is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligaments , can comprise up to 50 per cent of the body mass of some marine mammals during some points in their lives, and can range from 5 cm (2 in) thick in dolphins and smaller whales, to more than 30 cm (12 in) thick in some bigger whales, such as right and bowhead whales . However, this
1485-404: The melon as a head buckle. This is filled with air sacs and fat that aid in buoyancy and biosonar . The sperm whale has a particularly pronounced melon; this is called the spermaceti organ and contains the eponymous spermaceti , hence the name "sperm whale". Even the long tusk of the narwhal is a vice-formed tooth. In many toothed whales, the depression in their skull is due to the formation of
1540-404: The sperm whale , and the poorly understood beaked whales ) and the filter feeding Mysticeti or baleen whales (which includes species like the blue whale , the humpback whale and the bowhead whale ). Despite their highly modified bodies and carnivorous lifestyle, genetic and fossil evidence places cetaceans as nested within even-toed ungulates , most closely related to hippopotamus within
1595-406: The thermal conductivity of the common bottlenose dolphin 's blubber reveals its thickness and lipid content vary greatly amongst individuals and across life history categories. Blubber from emaciated dolphins is a poorer insulator than that from nonpregnant adults, which in turn have a higher heat conductivity than blubber from pregnant females and adolescents. Uqhuq , or uqsuq , ("blubber" in
1650-433: The tucuxi or Guiana dolphin, is able to use electroreception to sense prey. The external ear has lost the pinna (visible ear), but still retains a narrow ear canal . The three small bones or ossicles that transmit sound within each ear are dense and compact , and differently shaped from those of land mammals. The semicircular canals are much smaller relative to body size than in other mammals. A bony structure of
1705-665: The Pacific, Atlantic and Indian Oceans. However, northern and southern populations become genetically separated over time. In some species, this separation leads eventually to a divergence of the species, such as produced the southern right whale , North Pacific right whale and North Atlantic right whale . Migratory species' reproductive sites often lie in the tropics and their feeding grounds in polar regions. Thirty-two species are found in European waters, including twenty-five toothed and seven baleen species. Many species of whales migrate on
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1760-402: The amount of brain mass available for cognitive tasks. Allometric analysis of the relationship between mammalian brain mass (weight) and body mass for different species of mammals shows that larger species generally have larger brains. However, this increase is not fully proportional. Typically the brain mass only increases in proportion to somewhere between the two-thirds power (or the square of
1815-522: The animal in the water. For this reason, the usual terrestrial compact bones, which are finely woven cancellous bone , are replaced with lighter and more elastic material. In many places, bone elements are replaced by cartilage and even fat, thereby improving their hydrostatic qualities. The ear and the muzzle contain a bone shape that is exclusive to cetaceans with a high density, resembling porcelain . This conducts sound better than other bones, thus aiding biosonar . The number of vertebrae that make up
1870-522: The arctic diet also provide the calories needed to replace the lack of carbohydrates which are found in the diets of cultures in the rest of the world. In the 21st century, blubber contains man-made polychlorinated biphenyl (PCBs), carcinogens that damage human nervous, immune, and reproductive systems. The source of PCB concentrations is unknown. Since toothed whales are high on the food chain , they likely consume large amounts of industrial pollutants ( bioaccumulation ); even baleen whales , by merit of
1925-499: The blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator. Blubber aids buoyancy and streamlines the body, because the organized, complex collagenous network supports the noncircular cross sections characteristic of cetaceans. The buoyancy of blubber could be problematic for bottom-feeding marine mammals such as sirenians and the extinct marine sloths , both of which do or probably did have limited amounts of it for that reason. Research into
1980-439: The body wall. The stable lumbar and tail include the other vertebrae. Below the caudal vertebrae is the chevron bone . The front limbs are paddle-shaped with shortened arms and elongated finger bones, to support movement. They are connected by cartilage. The second and third fingers display a proliferation of the finger members, a so-called hyperphalangy. The shoulder joint is the only functional joint in all cetaceans except for
2035-416: The body. They are warm-blooded, i.e., they hold a nearly constant body temperature. Cetaceans have lungs, meaning they breathe air. An individual can last without a breath from a few minutes to over two hours depending on the species. Cetacea are deliberate breathers who must be awake to inhale and exhale. When stale air, warmed from the lungs, is exhaled, it condenses as it meets colder external air. As with
2090-403: The brain folds around the insula and expands more laterally than in terrestrial mammals. As a result, the cetacean prefrontal cortex (compared to that in humans) rather than frontal is laterally positioned. Brain size was previously considered a major indicator of intelligence . Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase
2145-543: The clade Whippomorpha . Cetaceans have been extensively hunted for their meat, blubber and oil by commercial operations. Although the International Whaling Commission has agreed on putting a halt to commercial whaling, whale hunting is still going on, either under IWC quotas to assist the subsistence of Arctic native people or in the name of scientific research, although a large spectrum of non-lethal methods are now available to study marine mammals in
2200-542: The cube root) and the three-quarters power (or the cube of the fourth root) of the body mass. m brain ∝ ( m body ) where k is between two-thirds and three-quarters. Thus if Species B is twice the size of Species A, its brain size will typically be somewhere between 60% and 70% higher. Comparison of a particular animal's brain size with the expected brain size based on such an analysis provides an encephalization quotient that can be used as an indication of animal intelligence. The neocortex of many cetaceans
2255-463: The day, during which whales do not respond to passing vessels unless they are in contact, leading to the suggestion that whales possibly sleep during such dives. Blubber Blubber is a thick layer of vascularized adipose tissue under the skin of all cetaceans , pinnipeds , penguins , and sirenians . It was present in many marine reptiles , such as ichthyosaurs and plesiosaurs . Lipid -rich, collagen fiber-laced blubber comprises
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2310-530: The fin are for stabilization and steering in the water. The male genitals and the mammary glands of females are sunken into the body. The male genitals are attached to a vestigial pelvis . The body is wrapped in a thick layer of fat, known as blubber . This provides thermal insulation and gives cetaceans their smooth, streamlined body shape. In larger species, it can reach a thickness up to one-half meter (1.6 feet). Sexual dimorphism evolved in many toothed whales. Sperm whales, narwhals , many members of
2365-403: The group's members. For example, the blue whale reaches a maximum confirmed length of 29.9 meters (98 feet) and a weight of 173 tonnes (190 short tons), making it the largest animal ever known to have existed. There are approximately 89 living species split into two parvorders : Odontoceti or toothed whales (containing porpoises , dolphins , other predatory whales like the beluga and
2420-405: The habitat conditions. Their body is well-adapted to their habitat, although they share essential characteristics with other higher mammals ( Eutheria ). They have a streamlined shape, and their forelimbs are flippers . Almost all have a dorsal fin on their backs, but this can take on many forms, depending on the species. A few species, such as the beluga whale , lack them. Both the flipper and
2475-434: The largest brain mass of any animal on Earth, averaging 8,000 cm (490 in ) and 7.8 kg (17 lb) in mature males. The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans. In some whales, however, it is less than half that of humans: 0.9% versus 2.1%. In cetaceans, evolution in the water has caused changes to the head that have modified brain shape such that
2530-422: The majority of cetaceans live in marine environments, a small number reside solely in brackish water or fresh water . Having a cosmopolitan distribution , they can be found in some rivers and all of Earth's oceans, and many species inhabit vast ranges where they migrate with the changing of the seasons. Cetaceans are famous for their high intelligence , complex social behaviour, and the enormous size of some of
2585-520: The manufacture of soap, leather, and cosmetics. Whale oil was used in candles as wax, and in oil lamps as fuel. A single blue whale can yield a blubber harvest of up to 50 tons. Blubber from whales and seals contains omega-3 fatty acids and vitamin D . Without the vitamin D, for example, the Inuit and other natives of the Arctic would likely suffer from rickets . There is evidence blubber and other fats in
2640-463: The middle and inner ear, the auditory bulla , is composed of two compact and dense bones (the periotic and tympanic). It is housed in a cavity in the middle ear; in the Odontoceti (apart from in the physeterids , this cavity is filled with dense foam and completely surrounds the bulla, which is connected to the skull only by ligaments. This may isolate the ear from sounds transmitted through the bones of
2695-426: The skull is significantly shortened and deformed. By shifting the nostrils to the top of the head, the nasal passages extend perpendicularly through the skull. The teeth or baleen in the upper jaw sit exclusively on the maxilla . The braincase is concentrated through the nasal passage to the front and is correspondingly higher, with individual cranial bones that overlap. In toothed whales, connective tissue exists in
2750-908: The skull, something that also happens in bats . Cetaceans use sound to communicate , using groans, moans, whistles, clicks or the 'singing' of the humpback whale. Odontoceti are generally capable of echolocation . They can discern the size, shape, surface characteristics, distance and movement of an object. They can search for, chase and catch fast-swimming prey in total darkness. Most Odontoceti can distinguish between prey and nonprey (such as humans or boats); captive Odontoceti can be trained to distinguish between, for example, balls of different sizes or shapes. Echolocation clicks also contain characteristic details unique to each animal, which may suggest that toothed whales can discern between their own click and that of others. While differences in ear structure associated with echolocating abilities are found amongst Cetacea, cranial asymmetry has also been found to be
2805-457: The spine varies by species, ranging from forty to ninety-three. The cervical spine , found in all mammals, consists of seven vertebrae which, however, are reduced or fused. This fusion provides stability during swimming at the expense of mobility. The fins are carried by the thoracic vertebrae , ranging from nine to seventeen individual vertebrae. The sternum is cartilaginous. The last two to three pairs of ribs are not connected and hang freely in
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#17328488302922860-500: The stomachs, whose individual sections can only be distinguished histologically . The liver is large and separate from the gall bladder . The kidneys are long and flattened. The salt concentration in cetacean blood is lower than that in seawater, requiring kidneys to excrete salt. This allows the animals to drink seawater. The urinary bladder is proportionally smaller in cetaceans than in land mammals. The testes are located internally, without an external scrotum . The uterus
2915-427: The total lung volume. For land mammals, in comparison, this value is usually about 15%. During inhalation, about twice as much oxygen is absorbed by the lung tissue as in a land mammal. As with all mammals, the oxygen is stored in the blood and the lungs, but in cetaceans, it is also stored in various tissues, mainly in the muscles. The muscle pigment, myoglobin , provides an effective bond. This additional oxygen storage
2970-695: The water. Balaenids ( right whales and bowhead whales ) have massive heads that can make up 40% of their body mass. Most mysticetes prefer the food-rich colder waters of the Northern and Southern Hemispheres, migrating to the Equator to give birth. During this process, they are capable of fasting for several months, relying on their fat reserves. The parvorder of Odontocetes – the toothed whales – include sperm whales, beaked whales, orcas, dolphins and porpoises. Generally their teeth have evolved to catch fish, squid or other marine invertebrates , not for chewing them, so prey
3025-407: The wild. Cetaceans also face severe environmental hazards from underwater noise pollution , entanglement in abandoned ropes and nets, collisions with ships, plastic and heavy metals build-up, to accelerating climate change , but how much they are affected varies widely from species to species, from minimally in the case of the southern bottlenose whale to the baiji (Chinese river dolphin) which
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