Whale

Whale (origin Old English hwæl from Proto-Germanic *hwalaz) is the common name for various marine mammals of the order Cetacea.^[1] The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which are smaller members of the suborder Odontoceti (toothed whales). The other cetacean suborder, Mysticeti (baleen whales), comprises filter feeders who eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. All cetaceans have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings (blowholes) on top of the head.

Whales range in size from the blue whale, the largest animal known to have ever existed,^[2] at 30 m (98 ft) and 180 tonnes (180 long tons; 200 short tons), to pygmy species such as the pygmy sperm whale at 3.5 m (11 ft). Whales inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3% to 13%.^[3] Whales are long-lived, humpback whales living for up to 77 years, while bowhead whales may live for more than a century.

Human hunting of whales from the seventeenth century until 1986 radically reduced the populations of some whale species.

Whales play a role in creation myths, for example among the Inuit, and they are revered by coastal people in countries such as Ghana and Vietnam.

Taxonomy

Cetaceans are divided into two suborders:

• The largest suborder, Mysticeti (baleen whales), is characterised by the presence of baleen, a sieve-like structure in the upper jaw made of keratin, which it uses to filter plankton from the water.
• Odontoceti (toothed whales) bear sharp teeth for hunting. Odontoceti includes dolphins and porpoises. If they were not considered to be whales, this would mean that the informal grouping 'whale' is not a clade.

Cetaceans and artiodactyls now are classified under the super-order Cetartiodactyla, which includes both whales and hippopotami. Whales are the hippopotamus's closest living relatives.^[4]

Evolution

All cetaceans, including whales, dolphins, and porpoises, are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). Both are related to the Indohyus, an extinct semi-aquatic deer-like ungulate, from which they split approximately 54 million years ago.^[5][6] These primitive cetaceans first took to the sea approximately 50 million years ago and became fully aquatic by 5–10 million years later.^[7] Their features became adapted for living in the marine environment. Major anatomical changes include streamlining of the body, the migration of the nasal openings toward the top of the cranium, the shrinking and eventual disappearance of the hind limbs, the modification of the forelimbs into flippers, and the growth of flukes on the tail.

Anatomy

As with all mammals, whales breathe air, are warm-blooded, nurse their young with milk from mammary glands, and have body hair.^[8] Beneath the skin lies a layer of fat called blubber, which stores energy and insulates the body. Whales have a spinal column, a vestigial pelvic bone, and a four-chambered heart. Typically, the neck vertebrae are fused, an adaptation trading flexibility for stability during swimming.^[9][10]

Blowhole(s)

Whales breathe via blowholes; baleen whales have two and toothed whales have one. These are located on the top of the head, allowing the animal to remain almost completely submerged while breathing. Breathing involves expelling stale air (which is warm and moist), as well as some mucus and excess water from the blowhole, forming an upward, steamy spout, followed by inhaling fresh air into the lungs.^[11] Spout shapes differ among species, which facilitates identification.

Appendages

The body shape is fusiform and the modified forelimbs, or fins, are paddle-shaped. The end of the tail is composed of two flukes, which propel the animal by vertical movement, as opposed to the horizontal movement of a fish tail. Although whales do not possess fully developed hind limbs, some (such as sperm whales and baleen whales) possess discrete rudimentary appendages, which may contain feet and digits. Most species have a dorsal fin.^[12][13] In 2006 a bottle-nosed dolphin with hind fins about as large as a human hand was captured in Japan.^[14][15]

Dentition

Toothed whales, such as the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum. Only in larger whales, where the cementum is worn away on the tip of the tooth, does enamel show.^[16]

Instead of teeth, baleen whales have a row of baleen plates on the upper side of their jaws that resemble the teeth of a comb.

Ears

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 aquatic mammals, such as whales, 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.^[17] The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater.^[18]

Life history and behaviour

Reproduction

Males are called 'bulls', females, 'cows' and all newborns, 'calves'. Most species do not maintain fixed reproductive partnerships. Females have several mates each season.^[19][20]

The female usually delivers a single calf, which is birthed tail-first to minimize the risk of drowning. Whale cows nurse by squirting milk into the mouths of their young. This milk is so rich in fat that it has the consistency of toothpaste.^[19] In many species, nursing continues for more than a year and is associated with a strong bond between mother and calf. Reproductive maturity typically occurs at seven to ten years. This mode of reproduction produces few offspring, but increases the survival probability of each one.

Socialization

Whales are known to teach, learn, cooperate, scheme, and grieve.^[21] The neocortex of many species of whale is home to elongated spindle neurons that, prior to 2007, were known only in hominids.^[22] In humans these cells are involved in social conduct, emotions, judgment, and theory of mind.^[23] 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.^[24]

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, avoid both predators and social contact during their period of rest.^[25]

A 2008 study found that wild sperm whales (Physeter macrocephalus) 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.^[26]

Surfacing behaviour

Many whales exhibit behaviours that expose large parts of their bodies to the air, such as breaching and tail slapping.

Sounding

Sounding is a term used for whales diving. Typically it is only used for longer dives. Before sounding, whales typically stay close to the surface for a series of short, shallow dives while building their oxygen reserves. They then make a sounding dive.

Lifespan

Lifespans vary among species and are not well characterised. Whaling left few older animals to observe directly. R.M. Nowak of Johns Hopkins University estimated that humpback whales may live as long as 77 years.^[27] In 2007, a nineteenth-century lance fragment was found in a bowhead whale off Alaska, which suggests the whale could be between 115 and 130 years old.^[28] Aspartic acid racemization in the whale eye, combined with a harpoon fragment, indicated an age of 211 years for another male, which, if true, would make bowheads the longest-lived extant mammal species.^[29][30] The accuracy of this age determination method has been questioned because racemization does not correlate well with other dating methods.^[31]

Vocalization

	Humpback Whale "Song" Recording of Humpback Whales singing and Clicking.
Problems playing this file? See media help.

Some species, such as the humpback whale, communicate using melodic sounds, known as whale song. These sounds may be extremely loud, depending on the species. Sperm whales only have been heard making clicks, while toothed whales (Odontoceti) use echolocation that may generate approximately 20,000 watts of sound (+73 dBm or +43 dBw)^[32] and be heard for many miles. Whale vocalization is likely to serve many purposes, including echolocation, mating, and identification.^[33]

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 producing human speech likely takes considerable effort.^[34]

Ecology

Whales are considered as "marine ecosystem engineers" for the following reasons:^[35]

• Whales are major consumers of fish and oceanic invertebrates.
• Whales act as reservoirs of nutrients, such as iron and nitrogen, and they recycle them both horizontally and vertically in the water column.
• Whale detritus provides energy and habitat for deep sea organisms.

Feeding

Whales generally are classed as predators. Their food ranges from microscopic plankton to very large animals.

Toothed whales eat fish and squid, which they hunt by the use of echolocation. Killer whales sometimes eat other marine mammals, including whales.

Baleen whales, such as humpbacks and blues, mainly eat krill when feeding in the higher latitudes (such as the Southern Ocean). They take in enormous amounts of seawater that they expel through their baleen plates; the krill in the seawater are retained on the plates and then swallowed.^[19] Whales do not drink seawater. They extract water indirectly from their food by metabolizing fat.^[19]

Whale pump

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 each year.^[36][37] Whales defecate at the oceans surface and this 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.^[38]

Whale fall

Upon death, whale carcasses fall to the deep ocean and being massive, with body weights of the range 30 to 160 tonnes (30,000 to 160,000 kg), provide a substantial habitat for marine creatures. 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 as per Smith & Baco (2003), comparable to other neritic biodiversity hotspots, such as cold seeps and hydrothermal vents.^[39]

Deterioration of whale carcasses happens though a series of three stages. 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. This is followed by the colonisation of bones and surrounding sediments (which contain organic matter) by enrichment opportunists, such as crustaceans and polychaetes, throughout a period of years. Finally, sulfophilic bacteria reduce the bones releasing hydrogen sulfide enabling the growth of 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 as per Smith & Baco (2003).^[39]

Species

Baleen whales

There are 10 recognised species of baleen whales.^[40]

Species	Description	Image
Blue whale (Balaenoptera musculus)	The blue whale is the largest animal that every lived on Earth, much larger than the largest dinosaur. This whale has been extensively hunted in the past. Between 1930 and 1971, about 280,000 blue whales have been killed. In 1966, when it became obvious not many blue whales were left, the International Whaling Commission (IWC) declared the blue whale a protected species. Blue whales produce very low frequency sounds (even below 20 Hz), which can be detected over large distances.[41] Average length is 24-27 m. The largest whale found was 33.58 m long. Females are larger than males. Typical weight is 100-120 tonnes, up to 190 tonnes. The skin is blue-grey coloured, mottled with grey-white. The large body is very broad. There is a large ridge on the head leading from the tip of the snout to the blowholes. The region of the blowholes is raised. A very small dorsal fin is located about 25% of the length in front of the tail flukes. The flippers are long and thin. The tail flukes are relatively small. There are 55-88 grooves extending from the chin to the navel. These grooves allow the mouth to extend considerably during feeding. The tongue, palate and baleen are black. The baleen is wide and relatively short (less that 1 m in length). While it has a worldwide distribution, it feeds in polar waters in summer and spends the winter in tropical and subtropical waters. Blue whales usually swim alone or in groups of 2 or 3 animals. They may group together on feeding grounds and form mixed-species groups with fin whales. The blue whale feeds almost exclusively on krill, rarely on small fish, such as capelin and sardines. Abundance: probably about 11,200 worldwide. In the North Atlantic there are only a few hundred blue whales left. Although the numbers are increasing, the blue whale is still endangered.[42]
Bowhead whale (Balaena mysticetus)	The bowhead whale was a target of early whaling operations. It was hunted for its oil and baleen. The Inuit people occasionally take a few whales in the Bering/Chukchi/Beaufort Sea area.[43] Typical length is 14-18 m. Females are slightly larger than males. Average weight is 60-90,000 kg. The bowhead whale is a very stocky animal with a large head. The mouth is bowed strongly upward. The skin is smooth and free of parasites. They are blue-black in colour with random light patches on the stomach and lower jaw. There is no dorsal fin. The flippers are relatively small and paddle-shaped. The tail flukes are wide and pointed. The baleen plates are narrow (30 cm) and very long (up to 4.3 m). Its lives in Arctic waters, near pack ice. There are 4 main bowhead whale areas: Spitzbergen, Hudson Bay/Davis Strait, Okhotsk Sea and Bering/Chukchi/Beaufort Sea. Usually the bowhead is seen alone or in small groups of up to 3 animals. It feeds on small crustaceans. The Bering/Chukchi/Beaufort Sea has about 7,800 animals. The Spitzbergen stock is probably extinct and the populations in the other areas have probably only a few hundred animals.[42]
Bryde's whale (Balaenoptera edeni)	Bryde's whale is easily confused with the sei whale. At close range, Bryde's whale can be easily recognised by the three parallel ridges on the head. The sei whale has only one central ridge. Bryde's whale is known to breach often in some areas. Bryde's whale is the least hunted of the rorqual species, mainly because it inhabits tropical and subtropical waters that were closed to whaling operations, because other species had been depleted in the area.[44] Average length is 11.5-14.5 m and average weight is 10-20,000 kg. Bryde's whale has 3 ridges on the head leading from the tip of the upper jaw to the blowholes. The Bryde's whale is dark grey on the back and lighter on the belly. They sometimes have light oval scars, caused by cookiecutter sharks. The dorsal fin is small and very curved. The flippers are medium-sized and thin, and somewhat rounded at the tip. The tail flukes are almost identical to those of the blue whale. It inhabits tropical and subtropical waters, between 40N and 40S latitude.It is usually alone or in groups of up to 10. They feed mainly on schooling fish, crustaceans and squid. The North Pacific population is probably about 20,000-30,000 animals. Not much is known about other areas.[42]
Fin whale (Balaenoptera physalus)	The fin whale is a fast swimmer, reaching speeds of 30 km/hr. It occasionally jumps clear of the water but does so less than other rorqual whales. They hardly ever show their tails before diving deep.[45] Size is 18-22 m, up to 27 m. Females are larger than males. Northern hemisphere fin whales are on average 1½ m shorter than Southern hemisphere fin whales. Weight ranges from 30 to 75,000 kg. The fin whale is a long and slender whale. The head resembles that of the blue whale. The fin whale is dark grey to brown in colour, with flanks that lighten towards the belly. The dark colour extends farther down on the left side than on the right, which is a unique feature in cetaceans. Most animals have a light chevron just behind the head. The large dorsal fin (60 cm high) is placed far back. The flippers are thin and pointed. The tail flukes are large, thin and pointed and look like blue whale flukes. It has a worldwide distribution, in deeper water. It is usually found in groups of up to 10, but larger groups (up to 100) are not uncommon. Its diet is mainly small crustaceans, but Northern hemisphere fin whales also feed on fish. There are roughly 100,000 in the southern hemisphere, but only 30,000 in the northern hemisphere, split 2 to 1 between the North Pacific and the North Atlantic.[42]
Gray whale (Eschrichtius robustus)	The grey whale spends the winter in San Ignacio lagoon, Baja California, Mexico. In this area, a lot of whale watching trips are organised and sometimes whales come so close to the boats that they can be touched. In summer they move to Alaska to feed. They travel along the US coast and the grey whale migration can be seen from several land-based spots along the coast. The grey whale is one of the few species who have come back from the brink of extinction. After a period of intense whaling, the species was nearly extinct, but it has recovered to the point that the US has taken it off its endangered species list. This species is 13.5 to 15 m in length and weighs up to 27,000 kg. The grey whale is mottled grey all over. The skin on the back has large yellow and white coloured patches caused by parasites like barnacle and whale lice . The mouth is slightly bowed. They have more bristles on the tips of their upper and lower jaws than any other whale species. The grey whale has no dorsal fin but a number of bumps on the back and tail stock. The flippers are large and paddle-shaped. The baleen plates are yellowish and about 40 cm long, with long, thick bristles. It resides in the North Pacific only. The grey whale used to be present in the North Atlantic as well, but has been hunted to extinction there. In summer, they feed in the Bering Sea. During migration, females with calves swim together in groups of about 6 adults. Later in the migration, there are groups of 3-5 non-pregnant females with 1 or 2 males. The last on the migration are juvenile animals. The grey whale feeds on the bottom. The prey consists of crustaceans, molluscs and small fish. The Eastern population is probably about 21,000 animals and is increasing in size at about 3.2% per year. The Western Pacific population is small, probably 100-200 animals.[42]
Humpback whale (Megaptera novaeangliae)	The humpback whale is probably one of the best known baleen whale species. The humpback whale is famous for its songs, of which even records have been made. The function of the songs is not clear. Most likely, the songs play a role in territorial behaviour and in courting. Only the males sing. These songs can be heard over large distances. Humpback whales have developed a unique way of catching fish: they dive down, then slowly circle to the surface, blowing bubbles on the way up. This will encircle the fish in a net of bubbles. The whales then surface with open mouths in the middle of the circle, gulping up the concentrated fish. Humpback whales migrate over large distances. In the North Pacific, Humpbacks spend the winter near Hawaii or Baja Californian and in summer, move to Alaska to feed.[46] This species is up to 19 m long and weighs up to 48,000 kg. The humpback whale is black all over, with very long flippers, which vary in colour from black to white. There are also lighter patches on the belly and chest. The underside of the tail flukes also have patterns, which are unique for each individual. From the blowhole to the tip of the snout and laterally towards the edges of the mouth there are conspicuous hair follicles on large bumps. The dorsal fin is small and set far back (about 2/3 of the body length). Its distribution is worldwide, but they follow fixed migration patterns. In the summer, they feed in the polar regions and they migrate to warmer waters in the winter for breeding. There are 3 isolated populations: North Pacific, North Atlantic and Southern Hemisphere. On the calving grounds, they usually form groups of about 10-12. During migration they travel in groups of 3-4. They feed on krill, plankton, and small schooling fish. There are about 5,500 in the North Atlantic, 2,500 in the North Pacific and about 12,000 in the Southern Hemisphere. There may also be a resident population of about 500 animals in the Indian Ocean. The humpback whale is considered to be a vulnerable species.[42]
Minke whale (Balaenoptera acutorostrata)	The minke whale became the target of whaling operations when the larger whales had declined to a level that made hunting them commercially unattractive. With all the larger whales reduced in numbers, the minke whales could multiply. Commercial fisheries for minke whales has restarted in Norway. In 1996, Norwegian whalers took 116 minke whales and in 1997, 503. In Greenland, the indigenous people are allowed to take 465 minke whales in 2 years.[47] This whale species is 7 to 10 m. It weighs 4,500 to 9,000 kg. The snout is pointed, and there is a clear under-bite. The back is black, whereas the belly region is white. They have a distinctive white band on the long, thin flippers. They have a well-developed curved dorsal fin, which looks like the dorsal fin of the bottlenose dolphin. Most Pacific animals have a light chevron on their flanks. It prefers temperate waters, around the world. They are usually found in small groups of 6 or less. They feed mainly on shoaling fish, and also on krill and plankton. In the North Pacific there are 18,000-27,000, in the Northeastern Atlantic: 90-135,000, in the Central Atlantic about 60,000, and in the Southern Hemisphere 200-400,000.[42]
Pygmy right whale (Caperea marginata)	The pygmy right whale is the smallest baleen whale species. It is not closely related to the right whales. The name comes from its appearance, mainly the shape of the mouth. Very little is known about this species. Since it is small and usually swims alone it is very difficult to find in the open sea. Most data is derived from dead stranded animals.[48] Its length is 5.5-6.5 m. It weighs 3,000-4,000 kg. The lower jaw is bowed and protrudes slightly. The body is stocky. They have a dark-coloured back, which becomes darker with age, and a pale belly. This whale has a prominent dorsal fin. The flippers are small and rounded and located under the body. The tail flukes are broad. The baleen plates are yellowish and are up to 70 cm in length. It is only known from the Southern hemisphere and usually is solitary. Diet is not well known, but probably plankton.[42]
Right whale (Eubalaena glacialis (Northern), Eubalaena australis (Southern)	These whales were named right whales, because for the early whalers they were the right ones to catch. They are slow, have lots of fat and stay afloat when killed. Only when the right and bowhead whales were depleted and factory ships were developed did the hunt for the rorqual whales start.[49] This 11-18 m long species weighs 30-75,000 kg. The right whale is extremely fat. There are numerous callosities on the mouth and head, caused by whale lice. They are black with large white patches on the belly. They have no dorsal fin and their flippers are paddle-shaped. The tail flukes are very wide, thin and pointed. Its distribution is in temperate oceans worldwide. The Southern right whale can be found from the Antarctic to Australia and South America and into the Indian Ocean. The Northern right whale is found in the North Pacific, from Japan and Baja California to the Aleutians. In the North Atlantic, the Northern right whale occurs from Florida and Spain in the South to Bear Island and Spitzbergen in the north. Its social structure is usually small groups of up to 5. They feeds mainly on krill. In the Northwest Atlantic about 1,000 are left; the Northeast Atlantic population is believed to be near extinction. The North Pacific population is probably nearly extinct. There are no signs of recovery in the Northern right whale populations. The total population of Southern right whales is probably about 1,500 and may be recovering slightly.[42]
Sei whale (Balaenoptera borealis)	The sei whale is probably the fastest swimmer among the baleen whales. It can reach speeds of close to 38 km/hr. The sei whale has been hunted extensively in the past. Because this whale resembles the Bryde's whale (only at close range can one see the single ridge on the head, whereas the Bryde's whale has 3 parallel ridges), combined quotas were set for these species until 1964. The catches were also recorded together. Consequently, there is no accurate catch statistics from before that date. In the 1960s, the annual catch of Sei whales was 10-15,000 per year. Hunting of sei whales was stopped in the 1970s.[50] Typical males are 12-18 m long, while females are up to 20 m long. Males weigh up to 22,000 kg, females up to 24,000 kg. The sei whale is dark grey on the back and also on the underside of the tail stock. The chin, throat and belly are white. This whale often has oval white marks, caused by lampreys and cookiecutter sharks. One long ridge runs from the tip of the upper jaw to the blowholes. The dorsal fin is large and placed far back (farther than that of the fin whale). It has a worldwide distribution, but not near the pack ice. It is usually seen alone or in pairs. When plenty of food is available they may form larger groups. Diet consists mostly of krill and other crustaceans. The sei whale also feeds on capelin, pollack (in Norwegian, they are called sei; the association with this fish gave the whale its name), anchovies, herring, cod and sardines. This species has been depleted by over-exploitation. After the end of commercial whaling for this species in 1980, no population estimates have been made. The North Atlantic population probably consists of a few thousand, the North Pacific population about 13,000 and the Antarctic populations about 40,000. This species is still vulnerable.[42]

Toothed whales

There are 26 recognised species of toothed whales, excluding dolphins and porpoises.

Species	Description	Image
Beaked whale (Berardius)	The beaked whales are a member of the Ziphiidae family which encompasses 22 different species of whales (Arnoux's beaked whale, Baird's beaked whale, northern bottlenose whale, southern bottlenose whale, Longman's beaked whale, Sowerby's beaked whale, Andrew's beaked whale, Hubbs' beaked whale, Blainville's beaked whale, Gervais' beaked whale, ginkgo-toothed beaked whale, Gray's beaked whale, Hector's beaked whale, strap-toothed whale, True's beaked whale, pygmy beaked whale, Perrin's beaked whale, Stejneger's beaked whale, spade-toothed whale, Shepherd's beaked whale, Cuvier's beaked whale and Deraniyagala's beaked whale[51]), all of which dive regularly to a depth surpassing 500 metres[52] to hunt their prey using a suction system aided by a pair of grooves on the under. The Ziphiidae family is the most widespread of the cetaceans, encompassing all of the oceans, but generally inhabiting offshore areas of at least a depth of 300 metres. The beaked whale ranges from 4-13 metres, and weighs 1-15 tons. These whales are similar to dolphins, in that they both have beaks, have a bulging forehead, and are roughly the same dimensions as one. They have differences, in that their tail fluke does not have a notch in it (excluding Shepherd's beaked whale). Species differentiation can be difficult, in that all species are quite similar, except minute differences in size, colour, and beak size.[53]	Blainville's beaked whale
Sperm whale (Physeter macrocephalus)	The sperm whale are known for their enormous heads; their brains are the largest in the animal kingdom with a volume of 8,000cm3 and weigh 17 pounds. These colossal creatures dive as deep as 1,000 metres in search of squid which makes up its diet, and must hold their breath for 90 minutes. They do this frequently, due to their need to eat about one ton of fish and squid per day. Female sperm whales congregate in pods of 15-20 and remain in tropical waters year-round, whereas males travel alone in Arctic or Antarctic waters, only migrating towards the equator to breed. Throughout the 18th and 19th centuries, sperm whales were heavily whaled for their oil. In spite off this, they are quite numerous.[54]	Mother and baby sperm whales
Dwarf sperm whale (Kogia sima)	The dwarf sperm whale is a smaller version of Physeter macrocephalus and is almost the same as its closer cousin Kogia breviceps. They are the only whales, apart from the Kogia breviceps to use a sort of pseudo-ink, like squids, by releasing up to 12 gallons of a reddish/brown liquid when startled which is known as "the squid-tactic". This blurs the vision of its attacker, allowing the whale to escape unharmed. These creatures dive to about 300 metres, near the ocean floor, to eat squid, fish and crustaceans in the subtropical waters of the world. Dwarf Sperm Whales grow to be around 2.7 metres in length, and weigh in at 300-600 pounds, with the females being slightly smaller than the males.[55]	Dwarf sperm whale
Pygmy sperm whale (Kogia breviceps)	The pygmy sperm whale is a smaller version of Physeter macrocephalus and is almost the same as its closer cousin Kogia sima. They are the only whales, apart from Kogia sima to use the "squid-tactic". These creatures dive to about 300 metres, near the ocean floor, to eat squid, fish and crustaceans in the subtropical and temperate waters of the world. Dwarf Sperm Whales grow to be around 3.5 metres in length, and weigh 700-1,000 pounds, with the females being slightly smaller than the males. Much of what is known about this species comes from dead individuals that wash up on beaches, or are entangled in fishing nets and consequently drown.[56]	Pygmy sperm whale skeleton
Beluga whale (Delphinapterus leucas)	The beluga is a white whale that inhabits the icy waters of the Arctic Ocean. To cope with the freezing temperatures of the Arctic, Belugas have blubber that makes up 40% of their body mass. Belugas are also unique among cetaceans as their skin turns yellow in July when it is time to shed it. Belugas are opportunistic, in that they eat octopi, squid, crustaceans, shellfish, snails, sand worms, and fish. Belugas give birth to one (rarely two) calves every two to three years, with gestation lasting around 15 months. They nurse for the first 18 months when their teeth grow in. Belugas are also known for their large pods that can include several hundred animals and are given their nickname "Canary of the Sea" due to their high inclination to vocalize.[57]	Beluga whale

Interaction with humans

Whaling

Some species of large whales are listed as endangered by multinational organizations, such as CITES, as well as governments and advocacy groups. This status is due primarily to the impact of whaling. Whales have been hunted commercially since the seventeenth century for whale oil, whale meat, baleen, and ambergris (a perfume ingredient from the intestine of sperm whales).^[58] More than two million whales were taken during the twentieth century,^[59] and by the middle of that century, many populations were severely depleted.

The International Whaling Commission banned commercial whaling in 1986.^[60] The ban is not absolute, and some whaling continues under the auspices of scientific research^[60] (sometimes not proved^[61]) or aboriginal rights. Current whaling nations are Norway, Iceland, and Japan as well as the aboriginal communities of Siberia, Alaska, and northern Canada.

Captivity

Belugas and orcas have been kept in captivity since 1861^[62] and 1961,^[63][64] respectively, for public display in a few locations.^[65][66] They are popular due to their intelligence, trainability,^[67][68] striking appearance,^[69] playfulness in captivity,^[70][71] and size. Belugas have also been kept captive for naval research in the US^[72] and Russia.^[73]

Most current captives were caught in the wild, since captive breeding has had limited success.^[74] There is controversy over captivity,^[65][75] with limited enrichment activities and tank sizes, though defenders say easy access for research^{[68][75][76][77]} and public viewing are beneficial.^[78] The whales have far larger family groups and ranges in the wild^[79] than in captivity.

Whale watching

An estimated 13 million people went whale watching globally in 2008, in all oceans except the Arctic.^[80][81] There are numerous rules and codes of conduct to minimize harassment of the whales.^[82] Iceland, Japan and Norway have both whaling and whale watching industries. Whale watching lobbyists are concerned that the most inquisitive whales, which approach boats very closely and provide much of the entertainment on whale-watching trips, will be the first to be taken if whaling is done in the same areas.^[83]

Bycatch

Several species of small whales are caught as bycatch while fishing for other species. In the Eastern Tropical Pacific tuna fishery, thousands of dolphins drowned in purse-seine nets, until preventive measures were introduced. Gear and deployment modifications, and eco-labelling (dolphin-safe or dolphin-friendly brands of tuna), have contributed to a reduction in dolphin mortality by tuna vessels.^[84]

Naval sonar

Environmentalists speculate that advanced naval sonar endangers some cetaceans, including whales. In 2003, British and Spanish scientists suggested in Nature that the effects of sonar trigger whale beachings and they point to signs that such whales have experienced decompression sickness.^[85] Responses in Nature the following year discounted the explanation.^[86]

Mass beachings occur in many species, mostly beaked whales that use echolocation for deep diving. The frequency and size of beachings around the world, recorded throughout the last thousand years in religious tracts, and more recently in scientific surveys, have been used to estimate the population of various whale species by assuming that the proportion of the total whale population beaching in any one year is constant. Beached whales can give other clues about population conditions, especially health problems. For example, bleeding around ears, internal lesions, and nitrogen bubbles in organ tissue suggest decompression sickness.^[21]

In fiction

The 1851 American novel, Moby-Dick by Herman Melville concerns a vexed captain's hunt for a gigantic white whale. Rudyard Kipling's 1902 Just So Stories includes the tale of "How the Whale got his Throat".^[87] The film Whale Rider directed by Niki Caro has a Maori girl ride a whale in her quest to be a suitable heir to the chiefship.^[88] An enormous whale called Monstro is the final antagonist featured in Walt Disney's 1940 animated film Pinocchio.

In mythology

Whales were little understood for most of human history as little of their lives could be seen from the surface of the ocean.^[89] Many cultures, even those that have hunted them, hold whales in awe and feature them in their mythologies. In China, Yu-kiang, a whale with the hands and feet of a human was said to rule the ocean.^[90] In the Tyrol region of Austria, it was said that if a sunbeam were to fall on a girl entering puberty, she would be carried away in the belly of a whale.^[91] Paikea, the youngest and favourite son of the chief Uenuku from the island of Mangaia (Cook Islands), was said by the Kati Kuri people of Kaikoura to have traveled from the Pacific Islands on the back of a whale many centuries before.^[92] The whale features 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.^[90] The Tlingit people of northern Canada said that the Orcas were created when the hunter Natsihlane carved eight fish from yellow cedar, sang his most powerful spirit song, and commanded the fish to leap into the water.^[93] 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.^[94] In East African legend, King Sulemani asked God that he might permit him to feed all the beings on earth. A whale came and ate until there was no corn left and then told Sulemani that he still was hungry and that there were 70,000 more in his tribe. Sulemani then prayed to God for forgiveness and thanked the creature for teaching him a lesson in humility.^[90]

Some cultures associate divinity with whales, such as among Ghanaians and Vietnamese, who occasionally hold funerals for beached whales, a throwback to Vietnam's ancient sea-based Austro-Asiatic culture.^{[95][96][97][98]}

The Bible mentions whales in Genesis 1:21, Job 7:12, Ezekiel and 32:2. The "sea monsters" in Lamentations 4:3 have been taken by some commentators to refer to marine mammals, in particular whales, although most modern versions use the word "jackals" instead.^[99] The story of Jonah being swallowed by a "big Fish" is told both in the Qur'an and in the Bible.^[100] The Old Testament contains the Book of Jonah and in the New Testament, Jesus mentions this story in Matthew 12:40.^[101]

In music

And God Created Great Whales, written in 1970 by American composer Alan Hovhaness, is a work for orchestra and whale songs, including the recorded sounds of humpback, bowhead, and killer whales.^[102] The song "Il n'y a plus rien", from French singer-songwriter Léo Ferré's eponymous album (1973), is an example of biomusic that begins and ends with recorded whale songs mixed with a symphonic orchestra and his voice.

See also

References

Further reading

• Carwardine, M. (2000). Whales, Dolphins and Porpoises. Dorling Kindersley. ISBN 0-7513-2781-6. .
• Williams, Heathcote (1988). Whale Nation. New York: Harmony Books. ISBN 0-517-56932-9. 

External links

Wikimedia Commons has media related to Whales.

Wikiquote has quotations related to: Whales

• Whale Evolution
• Oldest whale fossil confirms amphibious origins
• World Wide Fund for Nature (WWF) – information on whales, dolphins, and porpoises

Extant Cetacea species Kingdom Animalia Phylum Chordata Class Mammalia Infraclass Eutheria Superorder Laurasiatheria (unranked) Cetartiodactyla (unranked) Whippomorpha   Suborder Mysticeti (Baleen whales) Balaenidae Balaena Bowhead whale (B. mysticetus) Eubalaena (Right whales) Southern right whale (E. australis) North Atlantic right whale (E. glacialis) North Pacific right whale (E. japonica) Balaenopteridae (Rorquals) Balaenoptera Common minke whale (B. acutorostrata) Antarctic minke whale (B. bonaerensis) Sei whale (B. borealis) Bryde's whale (B. brydei) Pygmy Bryde's whale (B. edeni) Blue whale (B. musculus) Omura's whale (B. omurai) Fin whale (B. physalus) Megaptera Humpback whale (M. novaeangliae) Eschrichtiidae Eschrichtius Gray whale (E. robustus) Neobalaenidae Caperea Pygmy right whale (C. marginata)   Suborder Odontoceti (Toothed whales) (cont. below) Delphinidae (Oceanic dolphins) Cephalorhynchus Commerson's dolphin (C. commersonii) Chilean dolphin (C. eutropia) Haviside's dolphin (C. heavisidii) Hector's dolphin (C. hectori) Delphinus Long-beaked common dolphin (D. capensis) Short-beaked common dolphin (D. delphis) Feresa Pygmy killer whale (F. attenuata) Globicephala (Pilot whales) Short-finned pilot whale (G. macrorhynchus) Long-finned pilot whale (G. melas) Grampus Risso's dolphin (G. griseus) Lagenodelphis Fraser's dolphin (L. hosei) Lagenorhynchus Atlantic white-sided dolphin (L. acutus) White-beaked dolphin (L. albirostris) Peale's dolphin (L. australis) Hourglass dolphin (L. cruciger) Pacific white-sided dolphin (L. obliquidens) Dusky dolphin (L. obscurus) Lissodelphis (Right whale dolphins) Northern right whale dolphin (L. borealis) Southern right whale dolphin (L. peronii) Orcaella Irrawaddy dolphin (O. brevirostris) Australian snubfin dolphin (O. heinsohni) Orcinus Killer whale (O. orca) Peponocephala Melon-headed whale (P. electra) Pseudorca False killer whale (P. crassidens) Sotalia Tucuxi (S. fluviatilis) Costero (S. guianensis) Sousa Indo-Pacific humpback dolphin (S. chinensis) Atlantic humpback dolphin (S. teuszii) Stenella Pantropical spotted dolphin (S. attenuata) Clymene dolphin (S. clymene) Striped dolphin (S. coeruleoalba) Atlantic spotted dolphin (S. frontalis) Spinner dolphin (S. longirostris) Steno Rough-toothed dolphin (S. bredanensis) Tursiops Indo-Pacific bottlenose dolphin (T. aduncus) Burrunan dolphin (T. australis) Common bottlenose dolphin (T. truncatus)   Suborder Odontoceti (Toothed whales) (cont. above) Monodontidae Delphinapterus Beluga (D. leucas) Monodon Narwhal (M. monoceros) Phocoenidae (Porpoises) Neophocaena Finless porpoise (N. phocaeniodes) Phocoena Spectacled porpoise (P. dioptrica) Harbor porpoise (P. phocoena) Vaquita (P. sinus) Burmeister's porpoise (P. spinipinnis) Phocoenoides Dall's porpoise (P. dalli) Physeteridae Physeter Sperm whale (P. macrocephalus) Kogiidae Kogia Pygmy sperm whale (K. breviceps) Dwarf sperm whale (K. simus) Iniidae Inia Amazon river dolphin (I. geoffrensis) Lipotidae Lipotes Baiji (L. vexillifer) Platanistidae Platanista Ganges and Indus River dolphin (P. gangetica) Pontoporiidae Pontoporia La Plata dolphin (P. blainvillei) Ziphiidae (Beaked whales) Berardius Arnoux's beaked whale (B. arnuxii) Baird's beaked whale (B. bairdii) Hyperoodon Northern bottlenose whale (H. ampullatus) Southern bottlenose whale (H. planifrons) Indopacetus Tropical bottlenose whale (I. pacificus) Mesoplodon (Mesoplodont whales) Sowerby's beaked whale (M. bidens) Andrews' beaked whale (M. bowdoini) Hubbs' beaked whale (M. carlhubbsi) Blainville's beaked whale (M. densirostris) Gervais' beaked whale (M. europaeus) Ginkgo-toothed beaked whale (M. ginkgodens) Gray's beaked whale (M. grayi) Hector's beaked whale (M. hectori) Strap-toothed whale (M. layardii) True's beaked whale (M. mirus) Perrin's beaked whale (M. perrini) Pygmy beaked whale (M. peruvianus) Stejneger's beaked whale (M. stejnegeri) Spade-toothed whale (M. traversii) Tasmacetus Shepherd's beaked whale (T. sheperdi) Ziphius Cuvier's beaked whale (Z. cavirostris)