Whale

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Whale
An informal group
within the infraorder Cetacea
Temporal range:
Ma[1]
Southern right whale
Southern right whale
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Clade:
Cetaceamorpha
Infraorder: Cetacea
Groups included
  • Parvorder
    Mysticeti
    (baleen whales)
  • Parvorder
    Odontoceti
    (partially)
Cladistically included but traditionally excluded taxa
  • Family
    Delphinidae
    (dolphins and porpoises)
  • Superfamily
    Platanistoidea
    (Asian river dolphins)
  • Superfamily
    Inioidea
    (South American river dolphins)

Whales are a widely distributed and diverse group of fully

Ziphiidae
(the beaked whales), as well as the six families of dolphins and porpoises which are not considered whales in the informal sense.

Whales are fully aquatic, open-ocean animals: they can feed, mate, give birth, suckle and raise their young at sea. Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 29.9 metres (98 ft) and 190 tonnes (210 short tons) blue whale, which is the largest known animal that has ever lived. The sperm whale is the largest toothed predator on Earth. Several whale species exhibit sexual dimorphism, in that the females are larger than males.

Baleen whales have no teeth; instead, they have plates of baleen, fringe-like structures that enable them to expel the huge mouthfuls of water they take in while retaining the krill and plankton they feed on. Because their heads are enormous—making up as much as 40% of their total body mass—and they have throat pleats that enable them to expand their mouths, they are able to take huge quantities of water into their mouth at a time. Baleen whales also have a well-developed sense of smell.

Toothed whales, in contrast, have conical teeth adapted to catching fish or squid. They also have such keen hearing—whether above or below the surface of the water—that some can survive even if they are blind. Some species, such as sperm whales, are particularly well adapted for diving to great depths to catch squid and other favoured prey.

Whales evolved from land-living mammals, and must regularly surface to breathe air, although they can remain underwater for long periods of time. Some species, such as the sperm whale, can stay underwater for up to 90 minutes.[2] They have blowholes (modified nostrils) located on top of their heads, through which air is taken in and expelled. They are warm-blooded, and have a layer of fat, or blubber, under the skin. 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. Whales produce a great variety of vocalizations, notably the extended songs of the humpback whale. Although whales are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres and migrate to the equator to give birth. Species such as humpbacks and blue whales are capable of travelling thousands of miles without feeding. Males typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer; females bear all the responsibility for raising them. Mothers in some species fast and nurse their young for one to two years.

Once relentlessly hunted for their products, whales are now protected by international law. The North Atlantic right whales nearly became extinct in the twentieth century, with a population low of 450, and the North Pacific grey whale population is ranked Critically Endangered by the IUCN. Besides the threat from whalers, they also face threats from bycatch and marine pollution. The meat, blubber and baleen of whales have traditionally been used by indigenous peoples of the Arctic. Whales have been depicted in various cultures worldwide, notably by the Inuit and the coastal peoples of Vietnam and Ghana, who sometimes hold whale funerals. Whales occasionally feature in literature and film. A famous example is the great white whale in Herman Melville's novel Moby-Dick. 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. Whale watching has become a form of tourism around the world.

Etymology and definitions

The word "whale" comes from the

Proto-Indo-European *(s)kwal-o-, meaning "large sea fish".[3][4] The Proto-Germanic *hwalaz is also the source of Old Saxon hwal, Old Norse hvalr, hvalfiskr, Swedish val, Middle Dutch wal, walvisc, Dutch walvis, Old High German wal, and German Wal.[3] Other archaic English forms include wal, wale, whal, whalle, whaille, wheal, etc.[5]

The term "whale" is sometimes used interchangeably with

Delphinidae (oceanic dolphins).[6] Each species has a different reason for it, for example, the killer whale was named "Ballena asesina" 'killer whale' by Spanish sailors.[7]

The term "Great Whales" covers those currently regulated by the International Whaling Commission:[8] the Odontoceti family Physeteridae (sperm whales); and the Mysticeti families Balaenidae (right and bowhead whales), Eschrichtiidae (grey whales), and some of the Balaenopteridae (Minke, Bryde's, Sei, Blue and Fin; not Eden's and Omura's whales).[9]

Taxonomy and evolution

Phylogeny

The whales are part of the largely terrestrial mammalian

do not form a clade or order; the infraorder Cetacea includes dolphins and porpoises, which are not considered whales in the informal sense.[citation needed] The phylogenetic tree shows the relationships of whales and other mammals, with whale groups[citation needed
] marked in green.

Laurasiatheria
Ferae

(

carnivorans and allies)

 Perissodactyla 

(

rhinos, tapirs)

Artiodactyla
 Tylopoda 

(

camels, llamas)

 Artiofabula 
Suina

(pigs, hogs, peccaries)

 Cetruminantia 
 
Ruminants
 

(cattle, sheep, antelopes)

 Whippomorpha 
Hippopotamidae

 (hippos)

Cetacea
 
 
 
 
Archaeocetes
 

(Ambulocetus, Protocetus, Basilosaurus)

ancient whales

 
 
 
 
 
Mysticeti
 

(right whales, grey whales, rorquals)

baleen whales
 
 
Odontoceti
 
 Delphinoidea 

(dolphins, porpoises, beluga whales, narwhals)

 
Lipotoidea
 

(

river dolphins
)

(

sperm whales
)

 
Ziphoidea
 

(beaked whales)

 toothed whales 
c. 53 
Mya
c. 99 
Mya

Cetaceans are divided into two parvorders. The larger parvorder,

Odontocetes (toothed whales) are characterized by bearing sharp teeth for hunting, as opposed to their counterparts' baleen.[10]

Cetaceans and

Cetartiodactyla, often still referred to as Artiodactyla, which includes both whales and hippopotamuses. The hippopotamus and pygmy hippopotamus are the whales' closest terrestrial living relatives.[11]

Mysticetes

Mysticetes are also known as baleen whales. They have a pair of

.

The main difference between each family of mysticete is in their feeding adaptations and subsequent behaviour. Balaenopterids are the rorquals. These animals, along with the cetotheriids, rely on their throat pleats to gulp large amounts of water while feeding. The throat pleats extend from the mouth to the navel and allow the mouth to expand to a large volume for more efficient capture of the small animals they feed on. Balaenopterids consist of two genera and eight species.[14] Balaenids are the right whales. These animals have very large heads, which can make up as much as 40% of their body mass, and much of the head is the mouth. This allows them to take in large amounts of water into their mouths, letting them feed more effectively.[15] Eschrichtiids have one living member: the grey whale. They are bottom feeders, mainly eating crustaceans and benthic invertebrates. 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. This is an efficient method of hunting, in which the whale has no major competitors.[16]

Odontocetes

Odontocetes are known as toothed whales; they have teeth and only one blowhole. They rely on their well-developed sonar to find their way in the water. Toothed whales send out

beaked whales (ziphiids).[6]

The differences between families of odontocetes include size, feeding adaptations and distribution. Monodontids consist of two species: the beluga and the narwhal. They both reside in the frigid arctic and both have large amounts of blubber. Belugas, being white, hunt in large pods near the surface and around pack ice, their coloration acting as camouflage. Narwhals, being black, hunt in large pods in the aphotic zone, but their underbelly still remains white to remain camouflaged when something is looking directly up or down at them. They have no dorsal fin to prevent collision with pack ice.[18] Physeterids and Kogiids consist of sperm whales. Sperm whales consist the largest and smallest odontocetes, and spend a large portion of their life hunting squid. 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.[19] Ziphiids consist of 22 species of beaked whale. These vary from size, to coloration, to distribution, but they all share a similar hunting style. They use a suction technique, aided by a pair of grooves on the underside of their head, not unlike the throat pleats on the rorquals, to feed.[20]

As a formal clade (a group which does not exclude any descendant

(Pontoporiidae).

Evolution

Basilosaurus skeleton

Whales are descendants of land-dwelling mammals of the

cranium (blowholes), and the modification of the forelimbs into flippers (Basilosaurus 35 mya), and the shrinking and eventual disappearance of the hind limbs (the first odontocetes and mysticetes 34 mya).[26][27][28]

Whale morphology shows several examples of convergent evolution, the most obvious being the streamlined fish-like body shape.[29] Other examples include the use of echolocation for hunting in low light conditions — which is the same hearing adaptation used by bats — and, in the rorqual whales, jaw adaptations, similar to those found in pelicans, that enable engulfment feeding.[30]

Today, the closest living relatives of cetaceans are the

anthracotheres; nearly all anthracotheres became extinct at the end of the Pleistocene 2.5 mya, eventually leaving only one surviving lineage – the hippopotamus.[31]

Whales split into two separate parvorders around 34 mya – the baleen whales (Mysticetes) and the toothed whales (Odontocetes).[32][33][34]

Biology

Anatomy

Features of a blue whale
Features of a sperm whale skeleton

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

ziphiids). Whale skulls have small eye orbits, long snouts (with the exception of monodontids and ziphiids) and eyes placed on the sides of its head. Whales range in size from the 2.6-metre (8.5 ft) and 135-kilogram (298 lb) dwarf sperm whale to the 34-metre (112 ft) and 190-metric-ton (210-short-ton) blue whale. Overall, they tend to dwarf other cetartiodactyls; the blue whale is the largest creature on Earth. Several species have female-biased sexual dimorphism, with the females being larger than the males. One exception is with the sperm whale, which has males larger than the females.[35][36]

Odontocetes, such as the sperm whale, possess teeth with

whalebone, as opposed to teeth, made of keratin. Mysticetes have two blowholes, whereas Odontocetes contain only one.[37]

Breathing involves expelling stale air from the blowhole, forming an upward, steamy spout, followed by inhaling fresh air into the lungs; a humpback whale's lungs can hold about 5,000 litres (1,300 US gal) of air. Spout shapes differ among species, which facilitates identification.[38][39]

All whales have a thick layer of blubber. In species that live near the poles, the blubber can be as thick as 11 inches (28 cm). This blubber can help with buoyancy (which is helpful for a 100-ton whale), protection to some extent as predators would have a hard time getting through a thick layer of fat, and energy for fasting when migrating to the equator; the primary usage for blubber is insulation from the harsh climate. It can constitute as much as 50% of a whale's body weight. Calves are born with only a thin layer of blubber, but some species compensate for this with thick lanugos.[40][41]

Whales have a two- to three-chambered stomach that is similar in structure to those of terrestrial carnivores. Mysticetes contain a

pyloric chambers.[42]

Locomotion

Skeleton of a bowhead whale; notice the vestigial pelvis. Richard Lydekker, 1894

Whales have two flippers on the front, and a tail fin. These flippers contain four digits. Although whales do not possess fully developed hind limbs, some, such as the sperm whale and bowhead whale, possess discrete rudimentary appendages, which may contain feet and digits. Whales are fast swimmers in comparison to seals, which typically cruise at 5–15 kn, or 9–28 kilometres per hour (5.6–17.4 mph); the fin whale, in comparison, can travel at speeds up to 47 kilometres per hour (29 mph) and the sperm whale can reach speeds of 35 kilometres per hour (22 mph). The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility; whales are unable to turn their heads. When swimming, whales rely on their tail fin to propel them through the water. Flipper movement is continuous. 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. Some species log out of the water, which may allow them to travel faster. Their skeletal anatomy allows them to be fast swimmers. Most species have a dorsal fin.[28][43]

Whales are adapted for diving to great depths. In addition to their streamlined bodies, they can slow their heart rate to conserve oxygen; blood is rerouted from tissue tolerant of water pressure to the heart and brain among other organs;

haemoglobin and myoglobin store oxygen in body tissue; and they have twice the concentration of myoglobin than haemoglobin. Before going on long dives, many whales exhibit a behaviour known as sounding; they stay close to the surface for a series of short, shallow dives while building their oxygen reserves, and then make a sounding dive.[13][44]

Senses

Biosonar
by cetaceans
Sperm whale skeleton. Richard Lydekker, 1894.

The whale ear has specific adaptations to the marine environment. In humans, the middle ear works as an impedance equalizer between the outside air's low impedance and the cochlear fluid's high impedance. In whales, and other marine mammals, there is no great difference between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, whales receive sound through the throat, from which it passes through a low-impedance fat-filled cavity to the inner ear.[45] The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater.[46] Odontocetes send out high-frequency clicks from an organ known as a melon. This melon consists of fat, and the skull of any such creature containing a melon will have a large depression. The melon size varies between species, the bigger the more dependent they are on it. A beaked whale for example has a small bulge sitting on top of its skull, whereas a sperm whale's head is filled up mainly with the melon.[47][48][49][50]

The whale eye is relatively small for its size, yet they do retain a good degree of eyesight. As well as this, the eyes of a whale are placed on the sides of its head, so their vision consists of two fields, rather than a binocular view like humans have. When belugas surface, their lens and cornea correct the nearsightedness that results from the refraction of light; they contain both rod and cone cells, meaning they can see in both dim and bright light, but they have far more rod cells than they do cone cells. Whales do, however, lack short wavelength sensitive visual pigments in their cone cells indicating a more limited capacity for colour vision than most mammals.[51] Most whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas and a tapetum lucidum; these adaptations allow for large amounts of light to pass through the eye and, therefore, a very clear image of the surrounding area. They also have glands on the eyelids and outer corneal layer that act as protection for the cornea.[52][48]

The

olfactory lobes are absent in toothed whales, suggesting that they have no sense of smell. Some whales, such as the bowhead whale, possess a vomeronasal organ, which does mean that they can "sniff out" krill.[53]

Whales are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. However, some toothed whales have preferences between different kinds of fish, indicating some sort of attachment to taste. The presence of the Jacobson's organ indicates that whales can smell food once inside their mouth, which might be similar to the sensation of taste.[54]

Communication

Whale vocalization is likely to serve several purposes. Some species, such as the humpback whale, communicate using melodic sounds, known as

sonar that may generate up to 20,000 watts of sound (+73 dBm or +43 dBw)[55]
and be heard for many miles.

Captive whales have occasionally been known to mimic human speech. Scientists have suggested this indicates a strong desire on behalf of the whales to communicate with humans, as whales have a very different vocal mechanism, so imitating human speech likely takes considerable effort.[56]

Whales emit two distinct kinds of acoustic signals, which are called whistles and clicks:[57] Clicks are quick broadband burst pulses, used for

sonar, although some lower-frequency broadband vocalizations may serve a non-echolocative purpose such as communication; for example, the pulsed calls of belugas. Pulses in a click train are emitted at intervals of ≈35–50 milliseconds
, and in general these inter-click intervals are slightly greater than the round-trip time of sound to the target. Whistles are narrow-band frequency modulated (FM) signals, used for communicative purposes, such as contact calls.

Intelligence

Whales are known to teach, learn, cooperate, scheme, and grieve.

spindle neurons that, prior to 2007, were known only in hominids.[59] In humans, these cells are involved in social conduct, emotions, judgement, and theory of mind. Whale spindle neurons are found in areas of the brain that are homologous to where they are found in humans, suggesting that they perform a similar function.[60]

Bubble net feeding

brain-to-body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans.[62]

Small whales are known to engage in complex play behaviour, which includes such things as producing stable underwater toroidal air-core vortex rings or "bubble rings". There are two main methods of bubble ring production: rapid puffing of a burst of air into the water and allowing it to rise to the surface, forming a ring, or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed. They also appear to enjoy biting the vortex-rings, so that they burst into many separate bubbles and then rise quickly to the surface.[63] Some believe this is a means of communication.[64] Whales are also known to produce bubble-nets for the purpose of foraging.[65]

Larger whales are also thought, to some degree, to engage in play. The southern right whale, for example, elevates their tail fluke above the water, remaining in the same position for a considerable amount of time. This is known as "sailing". It appears to be a form of play and is most commonly seen off the coast of Argentina and South Africa. Humpback whales, among others, are also known to display this behaviour.[66]

Life cycle

Whales are fully aquatic creatures, which means that birth and courtship behaviours are very different from terrestrial and semi-aquatic creatures. Since they are unable to go onto land to calve, they deliver the baby with the fetus positioned for tail-first delivery. This prevents the baby from drowning either upon or during delivery.

A southern right whale tail-sailing

To feed the newborn, whales, being aquatic, must squirt the milk into the mouth of the calf. Nursing can occur while the mother whale is in the vertical or horizontal position. While nursing in the vertical position, a mother whale may sometimes rest with her tail flukes remaining stationary above the water. This position with the flukes above the water is known as "whale-tail-sailing." Not all whale-tail-sailing includes nursing of the young, as whales have also been observed tail-sailing while no calves were present.[67]

Being mammals, they have mammary glands used for nursing calves; they are weaned off at about 11 months of age. This milk contains high amounts of fat which is meant to hasten the development of blubber; it contains so much fat that it has the consistency of toothpaste.[68] As with humans, females whales typically deliver a single calf. The whale pregnancy/ gestation period lasts longer than the typical 9 month gestation period for humans. The whale gestation period is about 12 months. Once born, the absolute dependency of the calf upon the mother lasts from one to two years. Sexual maturity is achieved at around seven to ten years of age. The length of the developmental phases of a whale's early life varies between different whale species.[12]

As with humans, the whale mode of reproduction typically produces but one offspring approximately once each year. While whales have fewer offspring over time than most species, the survival probability for each calf is also greater than for most other species. Female whales are referred to as "cows." Female cows assume full responsibility for the care and training of their young. Male whales, referred to as "bulls," typically play no role in the process of calf rearing.

Most baleen whales reside at the poles. So, to prevent the unborn baleen whale calves from dying of frostbite, the baleen mother must migrate to warmer calving/mating grounds. They will then stay there for a matter of months until the calf has developed enough blubber to survive the bitter temperatures of the poles. Until then, the baleen calves will feed on the mother's fatty milk.[69]

With the exception of the humpback whale, it is largely unknown when whales migrate. Most will travel from the Arctic or Antarctic into the tropics to mate, calve, and raise during the winter and spring; they will migrate back to the poles in the warmer summer months so the calf can continue growing while the mother can continue eating, as they fast in the breeding grounds. One exception to this is the southern right whale, which migrates to Patagonia and western New Zealand to calve; both are well out of the tropic zone.[70]

Sleep

Unlike most animals, whales are conscious breathers. All mammals sleep, but whales cannot afford to become unconscious for long because they may drown. While knowledge of sleep in wild cetaceans is limited, toothed cetaceans in captivity have been recorded to 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.[71]

A 2008 study found that sperm whales sleep in vertical postures just under the surface in passive shallow 'drift-dives', generally during 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.[71]

Ecology

Foraging and predation

Polar bear with the remains of a beluga

All whales are carnivorous and predatory. Odontocetes, as a whole, mostly feed on

pinnipeds.[75][76]

Large whales, such as mysticetes, are not usually subject to predation, but smaller whales, such as monodontids or ziphiids, are. These species are preyed on by the orca. To subdue and kill whales, orcas continuously ram them with their heads; this can sometimes kill bowhead whales, or severely injure them. Other times they corral the narwhals or belugas before striking. They are typically hunted by groups of 10 or fewer orcas, but they are seldom attacked by an individual. Calves are more commonly taken by orcas, but adults can be targeted as well.[77]

These small whales are also targeted by terrestrial and pagophilic predators. The polar bear is well adapted for hunting Arctic whales and calves. Bears are known to use sit-and-wait tactics as well as active stalking and pursuit of prey on ice or water. Whales lessen the chance of predation by gathering in groups. This however means less room around the breathing hole as the ice slowly closes the gap. When out at sea, whales dive out of the reach of surface-hunting orcas. Polar bear attacks on belugas and narwhals are usually successful in winter, but rarely inflict any damage in summer.[78]

Whale pump

"Whale pump" – the role played by whales in recycling ocean nutrients.[79]

A 2010 study considered whales to be a positive influence to the productivity of ocean fisheries, in what has been termed a "whale pump." Whales carry nutrients such as nitrogen from the depths back to the surface. This functions as an upward biological pump, reversing an earlier presumption that whales accelerate the loss of nutrients to the bottom. This nitrogen input in the Gulf of Maine is "more than the input of all rivers combined" emptying into the gulf, some 23,000 metric tons (25,000 short tons) each year.

Whales defecate at the ocean's surface; their excrement is important for fisheries because it is rich in iron and nitrogen. The whale faeces are liquid and instead of sinking, they stay at the surface where phytoplankton feed off it.[79][81][82]

Whale fall

Upon death, whale carcasses fall to the deep ocean and provide a substantial habitat for marine life. Evidence of whale falls in present-day and fossil records shows that deep sea whale falls support a rich assemblage of creatures, with a global diversity of 407 species, comparable to other

neritic biodiversity hotspots, such as cold seeps and hydrothermal vents.[83]

Deterioration of whale carcasses happens though a series of three stages. Initially, moving organisms such as

chemoautotrophic organisms, which in turn, support other organisms such as mussels, clams, limpets, and sea snails. This stage may last for decades and supports a rich assemblage of species, averaging 185 species per site.[83][84]

Relationship with humans

Whaling

Whale Fishing: Woodcut by Thevet, Paris, 1574
Dutch whalers near Spitsbergen, their most successful port. Abraham Storck, 1690

right whales.[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. The most successful whaling nations at this time were the Netherlands, Japan, and the United States.[89]

Commercial whaling was historically important as an industry well throughout the 17th, 18th and 19th centuries. Whaling was at that time a sizeable European industry with ships from Britain, France, Spain, Denmark, the Netherlands and Germany, sometimes collaborating to hunt whales in the Arctic, sometimes in competition leading even to war.[90] By the early 1790s, whalers, namely the Americans and Australians, focused efforts in the South Pacific where they mainly hunted sperm whales and right whales, with catches of up to 39,000 right whales by Americans alone.[87][91] By 1853, US profits reached US$11,000,000 (£6.5m), equivalent to US$348,000,000 (£230m) today, the most profitable year for the American whaling industry.[92] Commonly exploited species included North Atlantic right whales, sperm whales, which were mainly hunted by Americans, bowhead whales, which were mainly hunted by the Dutch, common minke whales, blue whales, and grey whales. The scale of whale harvesting decreased substantially after 1982 when the International Whaling Commission (IWC) placed a moratorium which set a catch limit for each country, excluding aboriginal groups until 2004.[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.[94] Subsistence hunters typically use whale products for themselves and depend on them for survival. National and international authorities have given special treatment to aboriginal hunters since their methods of hunting are seen as less destructive and wasteful. 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.[95][96][97] In 1946, the IWC placed a moratorium, limiting the annual whale catch. Since then, yearly profits for these "subsistence" hunters have been close to US$31 million (£20m) per year.[93]

Other threats

Whales can also be threatened by humans more indirectly. They are unintentionally caught in fishing nets by commercial fisheries as bycatch and accidentally swallow fishing hooks. Gillnetting and Seine netting is a significant cause of mortality in whales and other marine mammals.[98] Species commonly entangled include beaked whales. Whales are also affected by marine pollution. High levels of organic chemicals accumulate in these animals since they are high in the food chain. They have large reserves of blubber, more so for toothed whales as they are higher up the food chain than baleen whales. Lactating mothers can pass the toxins on to their young. These pollutants can cause gastrointestinal cancers and greater vulnerability to infectious diseases.[99] They can also be poisoned by swallowing litter, such as plastic bags.[100] Advanced military sonar harms whales. Sonar interferes with the basic biological functions of whales—such as feeding and mating—by impacting their ability to echolocate. Whales swim in response to sonar and sometimes experience decompression sickness due to rapid changes in depth. Mass strandings have been triggered by sonar activity, resulting in injury or death.[101][102][103][104] Whales are sometimes killed or injured during collisions with ships or boats. This is considered to be a significant threat to vulnerable whale populations such as the North Atlantic right whale, whose total population numbers less than 500.[105]

Conservation

Diagram showing blue whale population trend through the 1900s
World population graph of blue whales

Whaling decreased substantially after 1946 when, in response to the steep decline in whale populations, the

functionally extinct. Conversely, the North Atlantic right whale was extirpated from much of its former range, which stretched across the North Atlantic, and only remains in small fragments along the coast of Canada, Greenland, and is considered functionally extinct along the European coastline.[108]

Map showing IWC members in blue
World map showing International Whaling Commission (IWC) members in blue

The IWC has designated two whale sanctuaries: the Southern Ocean Whale Sanctuary, and the Indian Ocean Whale Sanctuary. The Southern Ocean whale sanctuary spans 30,560,860 square kilometres (11,799,610 sq mi) and envelopes Antarctica.[109] The Indian Ocean whale sanctuary takes up all of the Indian Ocean south of 55°S.[110] The IWC is a voluntary organization, with no treaty. Any nation may leave as they wish; the IWC cannot enforce any law it makes.

There are at least 86 cetacean species that are recognized by the

Data Deficient" ranking.[118] 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.[119]

Whale watching

Whale watching off Bar Harbour, Maine

An estimated 13 million people went whale watching globally in 2008, in all oceans except the Arctic.[120] Rules and codes of conduct have been created to minimize harassment of the whales.[121] Iceland, Japan and Norway have both whaling and whale watching industries. Whale watching lobbyists are concerned that the most inquisitive whales, which approach boats closely and provide much of the entertainment on whale-watching trips, will be the first to be taken if whaling is resumed in the same areas.[122] Whale watching generated US$2.1 billion (£1.4 billion) per annum in tourism revenue worldwide, employing around 13,000 workers.[120] In contrast, the whaling industry, with the moratorium in place, generates US$31 million (£20 million) per year.[93] The size and rapid growth of the industry has led to complex and continuing debates with the whaling industry about the best use of whales as a natural resource.

In myth, literature and art

Engraving by Gilliam van der Gouwen depicting a stranded sperm whale being butchered on the Dutch coast, 1598

As marine creatures that reside in either the depths or the poles, humans knew very little about whales over the course of human history; many feared or revered them. The Vikings and various arctic tribes revered the whale as they were important pieces of their lives. In Inuit creation myths, when 'Big Raven', a deity in human form, found a stranded whale, he was told by the Great Spirit where to find special mushrooms that would give him the strength to drag the whale back to the sea and thus, return order to the world. In an Icelandic legend, a man threw a stone at a fin whale and hit the blowhole, causing the whale to burst. The man was told not to go to sea for twenty years, but during the nineteenth year he went fishing and a whale came and killed him.

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. Petroglyphs off a cliff face in Bangudae, South Korea show 300 depictions of various animals, a third of which are whales. Some show particular detail in which there are throat pleats, typical of rorquals. These petroglyphs show these people, of around 7,000 to 3,500 B.C.E. in South Korea, had a very high dependency on whales.[123]

The

Australian Aborigines viewed whales as bringers of good and joy. One exception is French Polynesia, where, in many parts, cetaceans are met with great brutality.[124]

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.[125]The god of the seas, according to Chinese folklore, was a large whale with human limbs.

In Vietnam, whales hold a sense of divinity. 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.[126][127][128][129]

Illustration by Gustave Doré of Baron Munchausen's tale of being swallowed by a whale. While the Biblical Book of Jonah refers to the Prophet Jonah being swallowed by "a big fish", in later derivations that "fish" was identified as a whale.

Whales have also played a role in sacred texts. The story of

medieval art (for example, on a 12th-century column capital at the abbey church of Mozac, France). The Bible also mentions whales in Genesis 1:21, Job 7:12, and Ezekiel 32:2. The "leviathan" described at length in Job 41:1-34 is generally understood to refer to a whale. The "sea monsters" in Lamentations 4:3 have been taken by some to refer to marine mammals, in particular whales, although most modern versions use the word "jackals" instead.[132]

Oswald Brierly
, 1867

In 1585,

Alessandro Farnese, 1585, and Francois, Duke of Anjou, 1582, were greeted on his ceremonial entry into the port city of Antwerp by floats including "Neptune and the Whale", indicating at least the city's dependence on the sea for its wealth.[133]

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.[134] It was believed that climbing inside a whale carcass and remaining there for a few hours would relieve symptoms of rheumatism.[135]

Whales continue to be prevalent in modern literature. For example,

Moby Dick features a "great white whale" as the main antagonist for Ahab. The whale is an albino sperm whale, considered by Melville to be the largest type of whale, and is partly based on the historically attested bull whale Mocha Dick. Rudyard Kipling's Just So Stories includes the story of "How the Whale got in his Throat". A whale features in the award-winning children's book The Snail and the Whale (2003) by Julia Donaldson and Axel Scheffler
.

Monstro
at the end of the film.

A recording of Song with a Humpback Whale by a team of marine scientists became popular in 1970.

Whales and Nightingales
).

In captivity

Beluga whales and trainers in an aquarium

Belugas were the first whales to be kept in captivity. Other species were too rare, too shy, or too big. The first beluga was shown at

St. Petersburg, and Sochi, or exported to other countries, such as Canada.[139] Most captive belugas are caught in the wild, since captive-breeding programs are not very successful.[140]

As of 2006, 30 belugas were in Canada and 28 in the United States, and 42 deaths in captivity had been reported up to that time.[139] A single specimen can reportedly fetch up to US$100,000 (£64,160) on the market. The beluga's popularity is due to its unique colour and its facial expressions. 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.[141]

Between 1960 and 1992, the Navy carried out a program that included the study of marine mammals' abilities with sonar, with the objective of improving the detection of underwater objects. A large number of belugas were used from 1975 on, the first being dolphins.[141][142] The program also included training them to carry equipment and material to divers working underwater by holding cameras in their mouths to locate lost objects, survey ships and submarines, and underwater monitoring.[142] A similar program was used by the Russian Navy during the Cold War, in which belugas were also trained for antimining operations in the Arctic.[143]

Aquariums have tried housing other species of whales in captivity. The success of belugas turned attention to maintaining their relative, the narwhal, in captivity. However, in repeated attempts in the 1960s and 1970s, all narwhals kept in captivity died within months. A pair of pygmy right whales were retained in an enclosed area (with nets); they were eventually released in South Africa. There was one attempt to keep a stranded Sowerby's beaked whale calf in captivity; the calf rammed into the tank wall, breaking its rostrum, which resulted in death. It was thought that Sowerby's beaked whale evolved to swim fast in a straight line, and a 30-metre (98 ft) tank was not big enough.[144] There have been attempts to keep baleen whales in captivity. There were three attempts to keep grey whales in captivity. Gigi was a grey whale calf that died in transport. Gigi II was another grey whale calf that was captured in the Ojo de Liebre Lagoon, and was transported to SeaWorld.[145] The 680-kilogram (1,500 lb) calf was a popular attraction, and behaved normally, despite being separated from his mother. A year later, the 8,000-kilogram (18,000 lb) whale grew too big to keep in captivity and was released; it was the first of two grey whales, the other being another grey whale calf named JJ, to successfully be kept in captivity.[145] There were three attempts to keep minke whales in captivity in Japan. They were kept in a tidal pool with a sea-gate at the Izu Mito Sea Paradise. Another, unsuccessful, attempt was made by the U.S. [146] One stranded humpback whale calf was kept in captivity for rehabilitation, but died days later.[147]

See also

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Bibliography

Books

Articles

Websites

News

Other

Further reading

  • "New Dawn". Walking with Prehistoric Beasts. 2002. Discovery Channel.
  • O'Connell, M.; Berrow, S. (2015). "Records from the Irish Whales and Dolphin Group for 2013". Irish Naturalists' Journal. 34 (2): 154–161.
  • "Whale" .
    New International Encyclopedia
    . 1905.
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