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Whale

2007 Schools Wikipedia Selection. Related subjects: Mammals

   A Fin whale
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   A Fin whale

   The term whale is ambiguous: it can refer to all cetaceans, to just the
   larger ones, or only to members of particular families within the order
   Cetacea. The last definition is the one followed here. Whales are those
   cetaceans which are neither dolphins (i.e. members of the families
   Delphinidae or Platanistoidea) nor porpoises. This can lead to some
   confusion because Orcas ("Killer Whales") and Pilot whales have "whale"
   in their name, but they are dolphins for the purpose of classification.

Origins and taxonomy

   Humpback Whale breaching
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   Humpback Whale breaching

   All whales, dolphins and porpoises are descendants of land-living
   mammals, most likely of the Artiodactyl order. They entered the water
   roughly 50 million years ago.

   Cetaceans are divided into two suborders:
     * The baleen whales are characterized by baleen, a sieve-like
       structure in the upper jaw made of keratin, which they use to
       filter plankton from the water. They are the largest species of
       whale.
     * The toothed whales have teeth and prey on fish, squid, or both. An
       outstanding ability of this group is to sense their surrounding
       environment through echolocation.

   A complete up-to-date taxonomical listing of all cetacean species,
   including all whales, is maintained at the Cetacea article.

Anatomy

   Physical characteristics of a baleen whale

   Like all mammals, whales breathe air into lungs, are warm-blooded, feed
   their young milk from mammary glands, and have some (although very
   little) hair. A young scientist, Eric Alexander Ivanov, in 1911, was
   the first to discover that the whale's ancestors lived on land, and
   that whales have adapted to a fully aquatic life. At first his findings
   were not accepted by the scientific community, but were later proved
   correct. Ivanov worked with others to stop whaling in the United
   States. Eric Ivanov died shortly after his goal was achieved.

   The body is fusiform, resembling the streamlined form of a fish. The
   forelimbs, also called flippers, are paddle-shaped. The end of the tail
   holds the fluke, or tail fins, which provide propulsion by vertical
   movement. Although whales generally do not possess hind limbs, some
   whales (such as sperm whales and baleen whales) sometimes have
   rudimentary hind limbs; some even with feet and digits. Most species of
   whale bear a fin on their backs known as a dorsal fin.

   Beneath the skin lies a layer of fat, the blubber. It serves as an
   energy reservoir and also as insulation. Whales have a four-chambered
   heart. The neck vertebrae are fused in most whales, which provides
   stability during swimming at the expense of flexibility.

   Whales breathe through blowholes, located on the top of the head so the
   animal can remain submerged. Baleen whales have two; toothed whales
   have one. The shapes of whales' spouts when exhaling after a dive, when
   seen from the right angle, differ between species. Whales have a unique
   respiratory system that lets them stay underwater for long periods of
   time without taking in oxygen. Some whales, such as the Sperm Whale,
   can stay underwater for up to two hours holding a single breath. The
   Blue Whale is the largest known mammal that has ever lived, and the
   largest living animal, at up to 30 m (93ft) long and 180 tons.

   Their skin has evolved hydrophilic properties. Its surface is covered
   with microscopic pores surrounded by nanoridges. Between these ridges
   there is a rubber-like gel which is excreted from the gaps between the
   skin cells. This gel contains enzymes that attack microbes, and the
   edge of the ridges makes it hard for smaller organisms to get attached.

   Whale flukes often can be used as identifying markings, as is the case
   for humpback whales. This is the method by which the publicized errant
   Humphrey the whale was identified in three separate sightings.

Anatomy of the ear

   While there are direct similarities between the ears of whales and
   humans, whales’ ears have specific adaptations to their underwater
   environment. In humans, the middle ear works as an impedance matcher
   between the outside air’s low-impedance and the cochlear fluid’s
   high-impedance. In aquatic mammals like whales, however, there is no
   great difference between the outer and inner environments. Instead of
   sound passing through outer ear to middle ear, whales receive sound
   through their lower jaw, where it passes through a low-impedance,
   fat-filled cavity.

Behaviour

   Humpback whale tail flip off coast of Moloka'i, Hawaii, 2005
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   Humpback whale tail flip off coast of Moloka'i, Hawaii, 2005

   Whales are widely classed as predators, but their food ranges from
   microscopic plankton to very large fish. Males are called bulls;
   females, cows. The young are called calves.

   Because of their environment (and unlike many animals), whales are
   conscious breathers: they decide when to breathe. All mammals sleep,
   including whales, but they cannot afford to fall into an unconscious
   state for too long, since they need to be conscious in order to
   breathe. It is thought that only one hemisphere of their brains sleeps
   at a time, so that whales are never completely asleep, but still get
   the rest they need. Whales are thought to sleep around 8 hours a day.

   Whales also communicate with each other using lyrical sounds. Being so
   large and powerful these sounds are also extremely loud and can be
   heard for many miles. They have been known to generate about 20,000
   acoustic watts of sound at 163 decibels.

   Females give birth to a single calf. Nursing time is long (more than
   one year in many species), which is associated with a strong bond
   between mother and young. In most whales reproductive maturity occurs
   late, typically at seven to ten years. This strategy of reproduction
   spawns few offspring, but provides each with a high rate of survival.

   The genital organs are retracted into cavities of the body during
   swimming, so as to be streamlined and reduce drag. Most whales do not
   maintain fixed partnerships during mating; in many species the females
   have several mates each season. At birth the newborn is delivered
   tail-first, so the risk of drowning is minimized. Whale mothers nurse
   the young by actively squirting the fatty milk into their mouths, a
   milk that according to German naturalist Dieffenbach, bears great
   similarities to cow's milk. Biologists compare the consistency of whale
   milk to cottage cheese; it must be thick, or else it will dissipate
   into the surrounding water.

Intelligence

   A once traditional but now discredited indicator of intelligence is
   overall brain size, since humans have bigger brains than most other
   animals. Whales have the largest brain of any animal. A typical sperm
   whale brain weighs about 7.8 kg, whereas a typical human brain weighs
   about 1.5 kg. While it may seem that this would indicate that five
   times greater intelligence, in mammals brain size is in approximate
   ratio to body size, and most of the extra capacity is used to manage
   the larger body. A slightly better indicator is the brain-body ratio:
   the size of the brain compared to body mass. Here humans have a
   decisive advantage. A human brain comprises about 2% of the human body
   mass, while the sperm whale's brain comprises only 0.02% of its body
   mass. A cow's brain is four times as large as a whale's on this
   measurement. On the other hand, a large proportion of a whale's body
   mass is blubber, which requires no brain power, and this distorts the
   ratio somewhat. However, because cetacean brains function quite
   differently from the human brain, even if whales had matching
   body/brain weight ratio to humans, it is not a conclusive indication of
   high intelligence. Simply, "overall" brain size is not a decisive
   criterion because it is now known that different parts of the brain
   regulate different functions, mostly physiological. Hummingbirds have
   an even higher brain-to-body ratio than humans. The next consideration
   is the structure of the brain. It is generally agreed that the growth
   of the neocortex, both absolutely and relative to the rest of the
   brain, during human evolution, has been responsible for the evolution
   of intelligence, however defined. In most mammals the neocortex has six
   layers, and its different functional areas (vision, hearing, etc) are
   sharply differentiated. The whale neocortex, on the other hand, has
   only five layers, and there is little differentiation of these layers
   according to function. This has led some to argue that the whale brain
   has not significantly evolved since the distant ancestors of the whale
   took to a marine lifestyle about 50 million years ago.

   Many people, particularly in the West, believe that cetaceans in
   general, and whales in particular, are highly intelligent animals. This
   belief has become one of a central argument against whaling (killing
   whales for food or other commercial reasons). Proponents of whale and
   dolphin intelligence cite the social behaviour of whales and their
   apparent capacity for communication as evidence of a sophisticated
   intellect, though scientists often carefully point out the difference
   between the social traits and intelligence of animals, which laymen
   often confuse. Given the radically different environment of whales and
   humans, and the size of whales compared to dolphins or chimpanzees, for
   instance, it is extremely difficult to test these views experimentally.

   The particular dispute in case of cetaceans is the conflict between
   social ability and abstract problem solving ability. Cetaceans,
   particularly dolphins, are highly social, and in addition they are
   generally friendly to humans. Some tests even indicate that they may
   even be social to the point of being self-aware. This has been the
   primary cause of perception among the public that cetaceans can be
   considered to be highly intelligent. However, canines and many other
   pack animals are also social (and are often perceived by the public to
   be intelligent due to such behaviour) but their problem solving
   abilities are usually rated lower than those of pigs. Dolphins also do
   poorly in (abstract) problem solving, which is considered a more
   rigorous indication of intelligence. Another misconception common
   amongst the public is to jump to the conclusion that if dolphins are
   intelligent, then that must mean that other cetaceans are intelligent:
   or, for that matter, if dolphins are not intelligent, then other
   cetaceans are not intelligent.

   "Into the Brains of Whales" by Mark Peter Simmonds was published in the
   Journal of Applied Animal Behaviour Science 100 (2006) 103-116. In this
   article it is asserted that behavior and social structures are accurate
   indicators of intelligence. On this premise, the author argue that that
   whales and dolphins are highly intelligent though most of his argument
   is based on dolphins, as it is impossible or too costly to conduct
   experiment or observation on whales. One indicator of intelligence, it
   is argued, is self-awareness. It is argued, though the finding is still
   disputed, that Bottlenose dolphins have been shown to be able to
   recognize themselves in a mirror. This behaviour had previously only
   been recorded in humans, elephant and apes. Also, the use of tools is
   another example of intelligence. An example of this form of
   intelligence has been observed in Indo-Pacific bottlenose dolphins who
   carry sponges on their beaks to protect themselves when foraging for
   food. Further evidence of "intelligence", as defined by Simmonds are
   emotions typically seen in humans such as grief, parental love and joy,
   though these are fairly common trait of many mammals especially pack
   animals. Another example of intelligence are complex social
   interactions and structures. These traits are seen in dolphins and
   whales. An example being that whales were observed to have a cohesion
   and reliance upon each other and that despite risk of dehydration,
   being stranded and risking shark attack, a group of false killer whales
   floated for 3 days in the shallows of the straits of Florida, USA to
   protect an injured male from shark attack. The whales became agitated
   when attempts by rescuers were made to separate them. The whales only
   calmed when reunited.

   On the other hand, another, and some argue to be more rigorus,
   definition of intelligience is "the ability to reason, plan, solve
   problems, think abstractly, comprehend complex ideas, learn quickly and
   learn from experience." In the case of dolphins, some assert that they
   do poorly in this respect. In a paper published in Biological Reviews
   of the Cambridge Philosophical Society, Paul Manger argue that the size
   of cecetarian brain is the evolutionary result of need to keep brain
   warm. Further Manger stated that, "You put an animal in a box, even a
   lab rat or gerbil, and the first thing it wants to do is climb out of
   it. If you don't put a lid on top of the bowl a goldfish it will
   eventually jump out to enlarge the environment it is living in,... But
   a dolphin will never do that. In the marine parks, the dividers to keep
   the dolphins apart are only a foot or two above the water between the
   different pools."

   From an evolutionary point of view, this is consistent with the
   principles of natural selection. Intelligence does not arise
   spontaneously: like any other animal capacity, it evolves under the
   pressure of the animal's environment. The human brain has evolved under
   the pressure of natural selection in a hostile terrestrial environment.
   The key primate characteristics - bipedalism and the opposable thumb -
   gave the early hominids the ability to manipulate their environment
   through the use of technology (by making tools). This unique adaptation
   created a virtuous cycle: more intelligence and consequent tool-making
   gave hominids with a decisive evolutionary advantage, leading to larger
   and more sophisticated brains functions, and thus to more tool-making.
   This process is one of the proposed explanations of the exponential
   growth of hominid intelligence over the past million years.

   By contrast, the whale has faced no such environmental stimuli to brain
   evolution. Whales live in an unchanging and benign environment with few
   natural predators. Their sole adaptation to their marine environment
   has been increasing size. The whale's lifestyle consists of swimming
   and eating, tasks which fish perform perfectly competently with very
   small brains in relative term. From an evolutionary point of view,
   there is no reason for whales to have evolved intelligence, since their
   survival does not require them to perform any tasks for which
   intelligence is necessary.

   Some whale species have a sophisticated social system. It is suggested
   that they can recognise and differentiate each individual whale. Many
   other animals, including insects, have complex social systems, and many
   others, such as birds, have sophisticated communications. Whales also
   have very acute hearing with well developed section of brain which
   govern this function, which gives them advanced echo-location
   capacities analogous to sonar - but so do bats. All this has led a
   number of, though far from all, zoologists to a conclusion that there
   is no convincing evidence for whale intelligence. A better
   understanding of whale communications and whale behaviour may solve
   this problem eventually.

Whales and humans

   Some species of large whales are endangered as a result of large-scale
   whaling during the nineteenth and twentieth centuries. For centuries
   large whales have been hunted for oil, meat, baleen and ambergris (a
   perfume ingredient from the intestine of sperm whales). By the middle
   of the 20th century, whaling left many populations severely depleted.
   The International Whaling Commission introduced an open-ended
   moratorium on all commercial whaling in 1986. For various reasons some
   exceptions to this moratorium exist; current whaling nations are
   Norway, Iceland and Japan and the aboriginal communities of Siberia,
   Alaska and northern Canada. For details, see whaling.

   Several species of small whales are caught as bycatch in fisheries for
   other species. In the tuna fishery in the Eastern Tropical Pacific
   thousands of dolphins would drown in purse-seine nets, until measures
   to prevent this were introduced. Fishing gear and deployment
   modifications, and eco-labelling (dolphin-safe or dolphin-friendly
   brands of canned tuna), have contributed to an estimated 96% reduction
   in the mortality of dolphins by tuna fishing vessels in recent years.
   In many countries, small whales are still hunted for food, oil, meat or
   bait.

   Environmentalists have long argued that some cetaceans, including
   whales, are endangered by sonar used by advanced navies. In 2003
   British and Spanish scientists suggested in Nature that sonar is
   connected to whale beachings and to signs that the beached whales have
   experienced decompression sickness. Mass whale beachings occur in many
   species, mostly beaked whales that use echolocation systems for deep
   diving). The frequency and size of beachings around the world, recorded
   over the last 1,000 years in religious tracts and more recently in
   scientific surveys, has been used to estimate the changing population
   size of various whale species by assuming that the proportion of the
   total whale population beaching in any one year is constant.

   Despite the concerns raised about sonar which may invalidate this
   assumption, this population estimate technique is still popular today.
   Researchers in the area ( Talpalar & Grossman, 2005) support the view
   that it is the combination of the high pressure environment of
   deep-diving with the disturbing effect of the sonar which causes
   decompression sickness and stranding of whales. Thus, an exaggerated
   startle response occurring during deep diving may alter orientation
   cues and produce rapid ascent.

   Following public concern, the U.S. Defense department has been ordered
   by the U.S. judiciary to strictly limit use of its Low Frequency Active
   Sonar during peacetime. Attempts by the UK-based Whale and Dolphin
   Conservation Society to obtain a public inquiry into the possible
   dangers of the Royal Navy's equivalent (the "2087" sonar launched in
   December 2004) have so far failed. The European Parliament on the other
   hand has requested that EU members refrain from using the powerful
   sonar system until an environmental impact study has been carried out.

   Conservationists are concerned that seismic testing used for oil and
   gas exploration may also damage the hearing and echolocation
   capabilities of whales. They also suggest that disturbances in magnetic
   fields caused by the testing may also be responsible for beaching.

   Some scientists and environmentalists suggest that some whale species
   are also endangered due to a number of other human activities such as
   the unregulated use of fishing gear, that often catch anything that
   swims into them, whales collisions with ships, toxins and the
   combination of toxins POPs among other threats.

Whales in culture

     * A kenning in Beowulf refers to the sea as the "whale-road".
     * Procopius mentions a whale, nicknamed Porphyrio by the Byzantines,
       who depleted fisheries in the Sea of Marmara.
     * The King James Version of the Bible mentions whales four times:
       "And God created great whales" ( Genesis 1:21); "Am I a sea, or a
       whale, that thou settest a watch over me? ( Job 7:12); "Thou art
       like a young lion of the nations, and thou art as a whale in the
       seas ( Ezekiel 32:2); and "For as Jonas [sic] was three days and
       three nights in the whale's belly; so shall the Son of man be three
       days and three nights in the heart of the earth" ( Matthew 12:40).
          + Nevertheless, the passages in question do not unambiguously
            refer to whales; modern translations tend to use other terms;
            for example the New International Version uses "creatures of
            the sea"; "monster of the deep"; "monster"; and "huge fish"
            respectively.
          + The story of Jonah being swallowed by a whale is mentioned in
            the Qur'an as well.
     * A whaling voyage is the plot of Herman Melville's novel Moby-Dick.
       In the book, Melville classed whales as "a spouting fish with a
       horizontal tail", this despite science suggesting otherwise the
       previous century. (His narrator acknowledged "the grounds upon
       which Linnaeus would fain have banished the whales from the waters"
       but writes that when he presented them to "my friends Simeon Macey
       and Charley Coffin, of Nantucket ... they united in the opinion
       that the reasons set forth were altogether insufficient. Charley
       profanely hinted they were humbug" (Chapter 32).) Melville's book
       is a classic of American literature: part adventure novel, part
       metaphysical allegory, and part natural history; it is essentially
       a summary of 19th century knowledge about the biology, ecology and
       cultural significance of the whale.
     * Some cultures associate some level of divinity with the whale, such
       as in some places in Ghana and the Vietnamese, who occasionally
       hold funerals for beached whales, a throwback to Vietnam's ancient
       sea-based Austro-asiatic culture.
     * Festivals celebrating whales have sprung in both Sitka and Kodiak
       Alaska. They feature speakers on marine biology and celebrate the
       creatures with art, music, whale watching cruises, and symposiums.

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