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[[Image:Humpback stellwagen edit.jpg|t<gallery widths="120">
  
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BlueWhale.jpg
  
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Balaenoptera_borealis_3.jpg
  
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</gallery>humb|right|A [[Humpback Whale]].]]
  
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'''Whales''' are marine mammals of order [[Cetacea]] which are neither [[dolphin]]s{{ndash}}members, in other words, of the families [[Oceanic dolphin|delphinidae]] or [[River dolphin|platanistoidae]]{{ndash}}nor [[porpoise]]s. They include the [[blue whale]], the [[largest organism|largest animal]] ever to have lived. [[Orca]]s, colloquially referred to as "killer whales", and [[pilot whale]]s have ''whale'' in their name but for the purpose of [[Taxonomy|classification]] they are actually dolphins. For centuries whales have been hunted for meat and as a source of valuable raw materials. By the middle of the 20th century, large-scale industrial whaling had left many populations severely depleted, rendering certain [[species]] seriously [[endangered species|endangered]].
  
   
  +
{{Taxobox
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==Origins and taxonomy==
 
  +
| name = Whale
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[[Image:Fin whale from air.jpg|thumb|right|A [[Fin Whale]].]]
  
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| image = Eubalaena glacialis with calf.jpg
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{{seealso|Evolution of cetaceans|List of whale species}}
  
  +
| image_size = 300px
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All [[cetacea]]ns, including whales, dolphins and porpoises, are descendants of land-living [[mammal]]s of the [[Artiodactyl]] [[order (biology)|order]] (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order [[Cetartiodactyla]] which includes both whales and [[hippopotamuses]]. In fact, whales are the closest living relatives of hippos; they evolved from a [[Most recent common ancestor|common ancestor]] at around 54 million years ago.<ref name=science_news>{{cite web
  
  +
| image_caption = [[North Atlantic right whale]]s, mother and calf
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| url = http://www.sciencedaily.com/releases/2007/12/071220220241.htm
  
  +
| regnum = [[Animal]]ia
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| title = Whales Descended From Tiny Deer-like Ancestors
  
  +
| phylum = [[Chordate|Chordata]]
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| accessdate = 2007-12-21
  
  +
| classis = [[Mammal]]ia
−
| author = Northeastern Ohio Universities Colleges of Medicine and Pharmacy (2007, December 21)
  
  +
| subclassis = [[Eutheria]]
−
| publisher = ScienceDaily
  
  +
| ordo = [[Cetacea]]
  +
}}
  +
'''Whale''' (origin Old English ''hƿæl'') is the common name for various [[marine mammal]]s of the order [[Cetacea]].<ref name="OED">{{cite book|title=Shorter Oxford English Dictionary|editor=Brown, Lesley|publisher=Oxford University press|location=Oxford|year=2007|edition=Sixth|volume=II|page=3611}}</ref> The term ''whale'' sometimes refers to all cetaceans, but more often it excludes [[dolphin]]s and [[porpoise]]s,<ref>[http://www.acsonline.org/education/taxonomy.html ACS – American Cetacean Society]. Acsonline.org. Retrieved on 2011-11-18.</ref> which belong to suborder ''Odontoceti'' ([[toothed whale]]s). This suborder also includes the [[sperm whale]], [[killer whale]], [[pilot whale]], and [[beluga whale]]. The other Cetacean suborder ''Mysticeti'' ([[baleen whale]]s) are [[filter feeder]]s that eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the [[blue whale]], the [[humpback whale]], the [[bowhead whale]] and the [[minke whale]]. All Cetacea 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<ref>{{cite web |url=http://science.howstuffworks.com/question687.htm | title=What is the biggest animal ever to exist on Earth?| publisher=How Stuff Works | accessdate=2007-05-29}}</ref> at {{convert|35|m|ft|abbr=on}} and {{convert|136|t}}, to various pygmy species, such as the [[pygmy sperm whale]] at {{convert|3.5|m|ft|abbr=on}}.
  +
  +
Whales collectively 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%.<ref>{{cite web
  +
|url=http://www.iwcoffice.org/conservation/estimate.htm#table
  +
|title=Whale Population Estimates
  +
|date=March 2010
  +
|accessdate=March 2010
  +
|publisher=International Whaling Commission
  +
}}</ref>
  +
For centuries, whales have been hunted for meat and as a source of raw materials. By the middle of the 20th century, however, industrial whaling had left many species seriously endangered, leading to the end of whaling in all but a few countries.
  +
  +
==Taxonomy==
  +
{{See also|List of whale species}}
  +
  +
Cetaceans are divided into two suborders:
  +
*The largest suborder, Mysticeti (baleen whales) are characterized by 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 also include dolphins and porpoises.
  +
  +
Both cetaceans and [[artiodactyl]] are now classified under the super-order [[Cetartiodactyla]] which includes both whales and [[hippopotamuses]]. Whales are the hippopotamus's closest living relatives.<ref name="physorg">{{cite web|url=http://www.physorg.com/news2806.html|title=Scientists find missing link between the whale and its closest relative, the hippo|last=Anon|date=25 January 2005|work=PhysOrg.com|publisher=PhysOrg.com|accessdate=6 May 2010}}</ref>
  +
  +
==Evolution==
  +
[[Image:Ambulocetus BW.jpg|thumb|right|220px|''[[Ambulocetus]] natans'' – a primitive whale]]
  +
{{See also|Evolution of cetaceans }}
  +
All cetaceans, including whales, dolphins and porpoises, are descendants of land-living mammals of the [[Artiodactyl]] [[order (biology)|order]] (even-toed [[ungulate]]s). Both are related to the [[Indohyus]] (an extinct [[semi-aquatic]] deer-like ungulate) from which they split around 54 million years ago.<ref name=science_news>{{cite web
  +
| url = http://www.sciencedaily.com/releases/2007/12/071220220241.htm
  +
| title = Whales Descended From Tiny Deer-like Ancestors
  +
| accessdate = 2007-12-21
  +
| author = Northeastern Ohio Universities Colleges of Medicine and Pharmacy
  +
| publisher = ScienceDaily
 
}}</ref><ref name="Ancestors_Tale">{{cite book
  
}}</ref><ref name="Ancestors_Tale">{{cite book
 
| first = Richard
  
| first = Richard
 
| last = Dawkins
  
| last = Dawkins
 
| authorlink = Richard Dawkins
  
| authorlink = Richard Dawkins
−
| title = [[The Ancestor's Tale|The Ancestor's Tale, A Pilgrimage to the Dawn of Life]]
 +
| title = [[The Ancestor's Tale]] |The Ancestor's Tale, A Pilgrimage to the Dawn of Life
 
| publisher = Houghton Mifflin Company
  
| publisher = Houghton Mifflin Company
 
| location = Boston
  
| location = Boston
 
| year = 2004
  
| year = 2004
  +
| isbn = 0-618-00583-8 }}</ref>
−
| isbn = 0-618-00583-8 }}</ref> Whales entered the water roughly 50 million years ago.<ref>{{cite web|url=http://news.bbc.co.uk/1/hi/sci/tech/1974869.stm|title=How whales learned to swim|publisher=BBC News|date=2002-05-08|accessdate=2006-08-20}}</ref>
  
  +
Primitive whales probably first took to the sea about 50 million years ago and became fully aquatic about 5–10 million years later.<ref>{{cite news
−
Cetaceans are divided into two suborders:
  
  +
|url=http://news.bbc.co.uk/1/hi/sci/tech/1974869.stm
−
*The [[baleen whale]]s 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 suborder of whale.
  
  +
|title=How whales learned to swim
−
*The [[toothed whale]]s have teeth and prey on fish, squid, or both. An outstanding ability of this group is to sense their surrounding environment through [[animal echolocation|echolocation]].
  
  +
|publisher=BBC News
−
A complete up-to-date taxonomical listing of all [[cetacea]]n species, including all whales, is maintained at the [[Cetacea]] article.
  
  +
|date=2002-05-08
  +
|accessdate=2006-08-20}}</ref>
   
 
==Anatomy==
  
==Anatomy==
−
Like all mammals, whales breathe air into lungs, are [[endotherm|warm-blooded]], feed their young [[milk]] from [[mammary gland]]s, and have some (although very little) hair.
 +
Like all mammals, whales breathe air, are [[warm-blooded]], nurse their young with milk from [[mammary gland]]s, and have body hair.{{Citation needed|date=March 2010}}
   
  +
Beneath the skin lies a layer of fat called [[blubber]], which stores energy and [[Thermal insulation|insulates]] the body. Whales have a spinal column, a [[vestigial structure|vestigial]] pelvic bone, and a four-chambered heart. The neck [[vertebrae]] are typically fused, trading flexibility for stability during swimming.{{Citation needed|date=March 2010}}
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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 whale]]s and [[baleen whale]]s) 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]].
  
   
  +
===Blowhole(s)===
−
Beneath the skin lies a layer of fat, called [[blubber]]. It serves as an energy reservoir and also as [[Thermal insulation|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. They have a pelvis bone, which is a [[vestigial structure]]
  
  +
[[File:Baleen parts.png|thumb|right|Features of a blue whale]]
−
Whales breathe through their [[blowhole (biology)|blowholes]], located on the top of the head so the animal can remain submerged. [[Baleen whale]]s have two; [[toothed whale]]s 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 35 m (105ft) long and 150 tons.
  
  +
Whales breathe via [[blowhole (biology)|blowholes]]; baleen whales have two and toothed whales have one. These are located on the top of the head, allowing the animal to remain mostly submerged whilst breathing. Breathing involves expelling excess water from the blowhole, forming an upward spout, followed by inhaling air into the lungs. Spout shapes differ among species and can help with identification.
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Whales generally live for 40-90 years,{{Fact|date=March 2008}} depending on their species, and on rare occasions can be found to live over a century. Recently a fragment of a lance used by commercial whalers in the 19th century has been found in a [[bowhead whale]] caught off Alaska, which showed the whale to be between 115 and 130 years old.<ref>{{cite web|url= http://www.news.com.au/dailytelegraph/story/0,22049,21897911-5001028,00.html|title=Hunting lance from 1800s found in whale| accessdate=2007-06-14}}</ref> Furthermore, a technique for dating age from [[aspartic acid]] [[racemization]] in the whale eye, combined with a [[harpoon]] fragment, indicates an age of 211 years for one male, making bowhead whales the longest lived [[extant]] mammal species.<ref>{{cite web|url=http://www.gi.alaska.edu/ScienceForum/ASF15/1529.html|title=Bowhead Whales May Be the World's Oldest Mammals | accessdate=2008-03-25|date=2008-02-15}}</ref><ref>{{cite journal|author=George, J.C. ''et al.''| title=Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization| journal= Can. J. Zool.| volume= 77|issue=4|pages= 571–580 |year=1999|doi=10.1139/cjz-77-4-571}} </ref>
  
−
Whale flukes often can be used as identifying markings, as is the case for [[humpback whale]]s. This is the method by which the publicized errant [[Humphrey the whale]] was identified in three separate sightings.
  
   
  +
===Appendages===
−
A toothed whale, like the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth which are comprised mostly of enamel on the tooth portion outside of the gum, whale teeth have cementum outside the gum. Only in larger whales does some enamel show where the cementum has been worn away on the tip of the tooth revealing the underlying enamel.<ref>"Common Characteristics of Whale Teeth" [http://www.antiquescrimshaw.org/index.htm here]</ref>
 
  +
The body shape is [[wikt:fusiform|fusiform]] and the modified forelimbs, or fins, are paddle-shaped. The end of the tail is composed of two [[:wiktionary:fluke|fluke]]s, 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 whale]]s and baleen whales) possess discrete rudimentary appendages, which may even have feet and digits. Most species have a [[dorsal fin]].{{Citation needed|date=March 2010}}
   
−
===Anatomy of the ear===
 +
===Dentition===
  +
Toothed whales, such as the sperm whale, possess teeth with [[cementum]] cells overlying [[dentine]] cells. Unlike human teeth, which are composed mostly of [[Tooth enamel|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 has been worn away on the tip of the tooth, does enamel show.<ref>
−
{{Seealso|Evolution of cetaceans}}
  
  +
"Common Characteristics of Whale Teeth" here [http://www.antiquescrimshaw.org/index.htm]</ref>
−
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 such as 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.<ref>{{cite web| url=http://instruct1.cit.cornell.edu/courses/bionb424/students2004/kls36/neuroanatomy.htm|title=Anatomy of a Whale's Ears| accessdate=2006-09-14}}</ref><ref>{{cite web |title=How is that whale listening? |url=http://www.eurekalert.org/pub_releases/2008-02/iop-hit020108.php |accessdate=2008-02-04}}</ref>
  
   
  +
Instead of teeth, Baleen whales have a row of plates on the upper side of their jaws that resemble the "teeth" of a comb.
−
==Behavior==
  
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[[Image:DSC 7334.JPG|thumb|right|A [[Humpback Whale]] breaching.]]
  
   
  +
===Ears===
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Whales are widely classed as [[predator]]s, but their food ranges from microscopic [[plankton]] to very large fish. Males are called bulls; females, cows. The young are called calves.
  
  +
The whale ear has specific adaptations to the [[Marine (ocean)|marine]] environment. In humans, the [[middle ear]] works as an impedance matcher between the outside air’s low [[Acoustic impedance|impedance]] and the [[cochlea]]r fluid’s high impedance. In aquatic mammals such as whales, however, 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.<ref>{{cite web
  +
|title=How is that whale listening?
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|url=http://www.eurekalert.org/pub_releases/2008-02/iop-hit020108.php
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|accessdate=February 4, 2008
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}}</ref> The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. <ref>{{
  +
cite journal
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|author=Nummela, Sirpa.
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|title=Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing.
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|journal=The Anatomical Record
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|volume=290
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|issue=6
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|pages=716–733
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|year=2007
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|doi=10.1002/ar.20528
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|last2=Thewissen
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|first2=J.G.M
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|last3=Bajpai
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|first3=Sunil
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|last4= Hussain
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|first4= Taseer
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|last5=Kumar
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|first5=Kishor}}</ref>
   
  +
==Life history/behavior==
−
As mammals, whales breathe air and must surface to get oxygen. This is done through a blowhole. Many whales also exhibit other [[Whale surfacing behaviour|surfacing behaviours]] such as breaching and tail slapping.
 
  +
===Reproduction===
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Males are called 'bulls', females, 'cows' and newborns, 'calves'.
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Most species do not maintain fixed partnerships and females have several mates each season.<ref name="po" /><ref>
  +
{{cite episode
  +
| series=[[Modern Marvels]]
  +
| title=Milk
  +
| url=http://www.history.com/minisites/modernmarvels
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| season=14
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| network=[[The History Channel]]
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| airdate=2008-01-07
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}}</ref>
   
  +
The female delivers usually a single calf tail-first to minimize the risk of drowning. Whale cows nurse by actively squirting milk, so fatty that it has the consistency of toothpaste, into the mouths of their young.<ref name="po"/> Nursing continues for more than a year in many species, and is associated with a strong bond between mother and calf. Reproductive maturity occurs typically at seven to ten years. This [[K selection|mode of reproduction]] produces few offspring, but increases survival probability.
−
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. This is thought because whales often sleep with only one eye closed.{{Fact|date=July 2008}}
  
   
  +
===Socialization===
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Whales also communicate with each other using lyrical sounds, called [[whale song]]. Being so large and powerful, these sounds are also extremely loud (depending on the species); sperm whales have only been heard making clicks, as all toothed whales ([[Odontoceti]]) use [[animal echolocation|echolocation]] and can be heard for many miles. They have been known to generate about 20,000 acoustic watts of sound at 163 decibels.<ref>{{cite web|url=http://www.makeitlouder.com/Decibel%20Level%20Chart.txt|title=Table of sound decibel levels|accessdate=2006-09-14}}</ref>
  
  +
Whales are known to teach, learn, cooperate, scheme, and even grieve.<ref name=wwwu>{{cite news
  +
|last=Siebert |first=Charles
  +
|title=Watching Whales Watching Us
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|work=New York Times Magazine
  +
|date=July 8, 2009
  +
|url=http://www.nytimes.com/2009/07/12/magazine/12whales-t.html?pagewanted=all
  +
}}</ref> The neocortex of many species of whale is home to elongated [[spindle neurons]] that, prior to 2007, were known only in hominids.<ref>
  +
cite journal
  +
|author=Watson, K.K.
  +
| title=Dendritic architecture of the Von Economo neurons
  +
| journal= Neuroscience
  +
| volume= 141
  +
|issue=3
  +
|pages= 1107–1112
  +
|year=2006
  +
|doi=10.1016/j.neuroscience.2006.04.084
  +
|last2=Jones
  +
|first2=T.K.
  +
|last3=Allman
  +
|first3=J.M.}}</ref> In humans these cells are involved in social conduct, emotions, judgment, and theory of mind.<ref>{{
  +
cite journal
  +
|author=Allman, John M.
  +
| title=Intuition and autism: a possible role for Von Economo neurons
  +
| journal= Trends Cogn Sci
  +
| volume= 9
  +
|issue=8
  +
|pages= 367–373
  +
|year=2005
  +
|doi=10.1016/j.tics.2005.06.008
  +
|last2=Watson
  +
|first2=Karli K.
  +
|last3=Tetreault
  +
|first3=Nicole A.
  +
|last4=Hakeem
  +
|first4=Atiya Y.}}</ref> Whale spindle neurons are found in areas of the brain homologous to where they are found in humans, suggesting that they perform a similar function. <ref>{{
  +
cite journal
  +
|author=Hof, Patrick R.
  +
| title=Structure of the cerebral cortex of the humpback whale, ''Megaptera novaeangliae'' (Cetacea, Mysticeti, Balaenopteridae)
  +
| journal= The Anatomical Record
  +
| volume= 290
  +
|issue=1
  +
|pages= 1–31
  +
|year=2007
  +
|doi=10.1002/ar.20407
  +
|last2=Van Der Gucht
  +
|first2=Estel}} </ref>
   
  +
===Sleep===
−
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 [[K selection|mode of reproduction]] spawns few offspring, but provides each with a high probability of survival in the wild.
  
  +
[[File:Humpback stellwagen edit.jpg|thumb |right|A Humpback Whale breaching.|alt=Photo of humpback whale with most of its body out of the water and its pectoral fins extended]]
  +
Unlike most animals, whales are conscious breathers. All mammals sleep, but whales cannot afford to become unconscious for long because they may drown. It is thought that only one hemisphere of the whale's brain sleeps at a time, so they rest but are never completely asleep.<ref name="Discovery">{{cite web|url=http://animals.howstuffworks.com/mammals/question643.htm|title=Do whales and dolphins sleep?|last=Anon|work=How Stuff Works|publisher=Discovery Communications|accessdate=14 February 2010}}</ref>
   
  +
===Surfacing behavior===
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The male genitals 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 newborn are delivered tail-first, minimising the risk of drowning. Whale cows nurse by actively squirting milk the consistency of [[toothpaste]] into the mouths of their young preventing loss to the surrounding aquatic environment.<ref>{{cite episode
  
  +
{{main|Whale surfacing behavior}}
−
| series=[[Modern Marvels]] | title=Milk | url=http://www.history.com/minisites/modernmarvels | season=14 | network=[[The History Channel]] | airdate=2008-01-07}}</ref>
  
  +
Many whales exhibit behaviors such as breaching and tail slapping that expose large parts of their bodies to the air.
−
==Human effects==
  
   
−
===Whaling===
 +
===Lifespan===
  +
Whale lifespans vary among species and are not well characterized. Whaling left few older individuals to observe directly. R.M. Nowak of [[Johns Hopkins University]] estimated that humpback whales may live as long as 77 years.<ref name="info">{{cite web|url=http://www.animalinfo.org/species/cetacean/meganova.htm#Maximum_age|title=Humpback Whale|last=Anon|year=2005|work=Animal Infor|publisher=Animal Info|accessdate=25 February 2010}}</ref> In 2007, a 19th century lance fragment was found in a [[bowhead whale]] off Alaska, suggesting the individual could be between 115 and 130 years old.<ref>{{cite news
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{{Main|Whaling}}
  
  +
|url=http://www.msnbc.msn.com/id/19195624/
−
[[Image:Petrified whale bone.JPG|A [[fossil]] whale bone found at California Beach|thumb|150px|left]]
  
  +
|title=Netted whale hit by lance a century ago
−
[[Image:International Whaling Commission members.svg|thumb|right|World map of International Whaling Commission (IWC) members/non-members(member countries in blue).]]
  
  +
|agency=Associated Press
−
[[Image:Blue Whale population, Pengo.svg|thumb|right|World population graph of Blue Whales (Balaenoptera musculus).]]
  
  +
|last=Conroy |first=Erin
−
[[Image:18th century arctic whaling.jpg|thumb|right|Eighteenth century engraving of Dutch whalers hunting [[Bowhead Whale]]s in
 
  +
|date=June, 2007
−
the Arctic.]]
  
  +
|accessdate=2009-10-05}}</ref> [[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 taxon|extant]] mammal species.<ref>{{cite web
  +
|url=http://www.gi.alaska.edu/ScienceForum/ASF15/1529.html
  +
|title=Bowhead Whales May Be the World's Oldest Mammals
  +
| accessdate=2008-03-25
  +
|date=2008-02-15}}</ref><ref>{{cite journal
  +
|author=George, J.C.
  +
| title=Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization
  +
| journal= Can. J. Zool.
  +
| volume= 77
  +
|issue=4
  +
|pages= 571–580
  +
|year=1999
  +
|doi=10.1139/cjz-77-4-571
  +
|last2=Bada
  +
|first2=Jeffrey
  +
|last3=Zeh
  +
|first3=Judith
  +
|last4=Scott
  +
|first4=Laura
  +
|last5=Brown
  +
|first5=Stephen E.
  +
|last6=O'Hara
  +
|first6=Todd
  +
|last7=Suydam
  +
|first7=Robert}}</ref>
  +
The accuracy of this technique has been questioned because racemization did not correlate well with other dating methods.<ref name="Racemization">{{cite web|url=http://pubs.acs.org/subscribe/journals/tcaw/10/i02/html/02brignole.html|title=Amino Acid Racemization|last=Brignole|first=Edward|coauthors=McDowell, Julie|work=Today's chemist at work|publisher=American Chemical Society|accessdate=25 February 2010}}</ref>
   
  +
===Vocalization===
−
Some species of large whales are listed by various [[interest group|watchdog groups]] and governments as endangered due to reduced population resulting from commercial whaling. Large whales have been hunted commercially for [[whale oil]], [[whale meat|meat]], [[baleen]] and [[ambergris]] (a perfume ingredient from the intestine of [[sperm whale]]s) since the 1600s.<ref>http://www.whaling.jp/english/history.html</ref> By the middle of the 20th century, whaling left many populations severely depleted.
  
  +
{{Listen|filename=Humpbackwhale2.ogg|title=Humpback Whale "Song"|description=Recording of Humpback Whales singing and Clicking.|format=[[Ogg]]}} Some species, such as the humpback whale, communicate using melodic sounds, known as [[whale song]]. These sounds can be extremely loud, depending on the species. Sperm whales have only been heard making clicks, while toothed whales ([[Odontoceti]]) use [[animal echolocation|echolocation]] that can generate about 20,000 watts of sound (+73&nbsp;[[dBm]] or +43&nbsp;[[Decibel watt|dBw]]<ref>[http://www.radio-electronics.com/info/formulae/decibels/dBm_dBW_table.php dBm – dBw Watts conversion chart], [http://www.radio-electronics.com/ Radio-Electronics.com]</ref>) and be heard for many miles. Whale vocalization is likely to serve many purposes, including [[Animal echolocation|echolocation]], mating, and identification.{{citation needed|date=December 2010}}
   
  +
==Ecology==
−
The [[International Whaling Commission]] introduced a six year moratorium on all commercial whaling in 1986, which has been extended to the present day. The moratorium is not absolute, however, and some whaling continues to be practiced under the auspice of research or [[Aboriginal whaling|aboriginal rights]]; current whaling nations are [[Norway]], [[Iceland]] and [[Japan]] and the aboriginal communities of [[Siberia]], [[Alaska]] and northern [[Canada]]. For details, see [[whaling]].
  
  +
===Feeding===
  +
Whales are generally classed as predators, but their food ranges from microscopic [[plankton]] to very large animals.
   
  +
Toothed whales eat fish and squid which they hunt by use of [[animal echolocation|echolocation]]. [[Orcas]] sometimes eat other marine mammals, including whales.
−
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 were drowned 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 a 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.
  
   
  +
Baleen whales such as humpbacks and blues feed only in arctic waters, eating mostly [[krill]]. They imbibe enormous amounts of seawater which they expel through their baleen plates. The water is then expelled and the krill is retained on the plates and then swallowed.<ref name=po>{{cite episode
  +
|publisher=Discovery Channel Blue Ocean
  +
|title=Blue Whale
  +
|accessdate=October 5, 2009
  +
}}</ref> Whales do not drink seawater but indirectly extract water from their food by metabolizing fat.<ref name="po"/>
   
−
===Sonar interference===
  
−
Environmentalists have long speculated that some cetaceans, including whales, are endangered by [[sonar]] used by advanced navies. In 2003 British and Spanish scientists suggested in ''[[Nature (journal)|Nature]]'' that sonar is connected to whale beachings and to signs that the beached whales have experienced decompression sickness.<ref>{{cite web| url=http://news.bbc.co.uk/2/hi/science/nature/3173942.stm |title=Sonar may cause Whale deaths |publisher=BBC News |date=2003-10-08 |accessdate=2006-09-14}}</ref> Responses in Nature the following year discounted the explanation.<ref>{{cite journal |author=Piantadosi CA, Thalmann ED |journal=Nature|title=Pathology: whales, sonar and decompression sickness |date=2004-04-15 |volume=428 |issue=6894|pmid=15085881 |pages=716–718}}</ref> Mass [[beached whale|whale beaching]]s 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.
  
   
  +
===Naval sonar===
−
Despite the concerns raised about sonar which may invalidate this assumption, this population estimate technique is still popular today. Talpalar and Grossman argue 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. <ref>{{cite journal |journal =Undersea Hyperb Med |author=|title=Sonar versus whales: noise may disrupt neural activity in deep-diving cetaceans |date=2005 March-April |pmid=15926306|issue=2|pages=135–139|volume=32}}</ref> Thus, an exaggerated startle response occurring during deep diving may alter orientation cues and produce rapid ascent.
  
  +
{{See also|Marine Mammals and Sonar}}
  +
Environmentalists speculate that advanced naval [[sonar]] endangers some cetaceans, including whales. In 2003 British and Spanish scientists suggested in ''[[Nature (journal)|Nature]]'' that the effects of sonar trigger [[whale beaching]]s and to signs that such whales have experienced decompression sickness.<ref>{{cite news
  +
| url=http://news.bbc.co.uk/2/hi/science/nature/3173942.stm
  +
|title=Sonar may cause Whale deaths
  +
|publisher=BBC News
  +
|date=2003-10-08
  +
|accessdate=2006-09-14}}</ref> Responses in ''Nature'' the following year discounted the explanation.<ref>{{
  +
cite journal
  +
|author=Piantadosi CA, Thalmann ED
  +
|journal=Nature
  +
|title=Pathology: whales, sonar and decompression sickness
  +
|date=2004-04-15
  +
|volume=428
  +
|issue=6894
  +
| doi = 10.1038/nature02527a
  +
|pmid=15085881
  +
|pages=716–718}}</ref>
   
  +
Mass beachings occur in many species, mostly [[beaked whale]]s that use echolocation 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, 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.<ref name=wwwu/>
−
Following public concern, the U.S. Defense department was ordered by the US circuit court in California 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 "[[Sonar 2087|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.
  
   
  +
Following public concern, the U.S. Defense department was ordered by the 9<sup>th</sup> Circuit Court 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 "[[Sonar 2087|2087]]" sonar launched in December 2004) failed as of 2008. The European Parliament has requested that EU members refrain from using the powerful sonar system until an [[environmental impact study]] has been carried out.
−
===Other environmental disturbances===
  
−
Conservationists are concerned that seismic testing used for oil and gas exploration may damage the hearing and echolocation capabilities of whales and suggest that such testing may also be responsible for beaching. <ref>{{cite web| url=http://www.sustainability.ca/Docs/Impact%20of%20Seismic%20Surveys%20on%20Whales.pdf?CFID=9951883&CFTOKEN=72165442| title=Seismic testing and the impacts of high intensity sound on whales| accessdate=2006-09-14}}</ref>
  
   
−
Other human activities have been suggested to adversely impact whale populations, ranging from the unregulated use of fishing gear which catches anything that swims into it, to collisions with ships. Environmental toxins and the combination of toxins, particularly [[Persistent Organic Pollutant]]s (POPs) (which concentrate up the food chain), have been shown to cause hearing loss by inhibiting the function of outer [[hair cells]] in the [[cochlea]] of the ear, and exposure to these toxins might affect whale echolocation, leading to beaching .<ref>{{cite web |url=http://www.yale.edu/opa/newsr/06-04-13-02.all.html |title=Yale Researchers Find Environmental Toxins Disruptive to Hearing in Mammals |date=2006-04-13}}</ref>
  
   
  +
===In mythology===
−
Whales are also threatened by [[climate change]] and [[global warming]]. As the [[Antarctic Ocean]] warms, [[krill]] populations, that are the main food source of some species of whales, reduce dramatically, being replaced by jelly like [[salp]]s.{{Fact|date=April 2007}}
  
  +
[[File:Nantucket historical assocation whaling museum weather vane.jpg|right |thumb |Whale weather-vane atop the Nantucket Historical Association Whaling Museum displaying a [[Sperm Whale]].]]
   
  +
Whales were little understood for most of human history as they spend up to 90% of the lives underwater, only surfacing briefly to breathe.<ref>{{cite web|url=http://www.oceanicresearch.org/education/wonders/spermwhales.htm|title=Sperm Wales:The deep rivers of the ocena|last=Bird|first=Jonathon|work=The Wonders of the Seas|publisher=jonathon.bird.org|accessdate=14 February 2010}}</ref> They also include the largest animals on the planet, so it is not surprising that many cultures, even those that have hunted them, hold them in awe and feature them in their mythologies.
−
==Whales in culture==
  
  +
−
[[Image:Nantucket historical assocation whaling museum weather vane.jpg|right|thumb|Whale weather-vane atop the Nantucket Historical Association Whaling Museum.]]
  
  +
In China, [[Yu-kiang]], a whale with the hands and feet of a man was said to rule the ocean.<ref name="Jones">{{cite web|url=http://adairjones.wordpress.com/2009/09/29/in-search-of-whales-in-literature/|title=In search of . . . whales in literature|last=Jones |first=Adair|work=Wordpress.com|publisher=wordpress|accessdate=14 February 2010}}</ref>
−
Whales are frequently portrayed in literature as violent creatures who attack shipping and kill or eat sailors, despite overwhelming scientific evidence to the contrary. This is especially true in literature written prior to the modern scientific study of the creatures, or in [[period literature]]. A common whale-themed [[plot device]] concerns mariners who are swallowed whole by a whale, and find themselves trapped alive in the creature's belly. In some instances, the victims of these encounters are able to escape, often by causing the whale sufficient gastronomic distress that it is forced to expel them; in other such occurrences in fiction, the victim is doomed.
  
  +
  +
In the Tyrol region of Austria it was said that if a sunbeam were to fall on a maiden entering womanhood, she would be carried away in the belly of a whale.<ref name="Jones"/>
  +
  +
[[Paikea]], the youngest and favourite son of the chief Uenuku from the island of [[Mangaia]] in the present day [[Cook Islands]] in New Zealand was said by the Kati Kuri people of [[Kaikoura]] to have come from the Pacific Islands on the back of a whale many centuries before.<ref>{{cite web|url=http://collections.tepapa.govt.nz/exhibitions/whales/EducationResource.aspx?irn=198|title=Whales|last=Anon|work=Tinirau education resource|accessdate=14 February 2010}}</ref> The novel and movie [[Whale Rider]] follow the trials of a girl named Paikia, who lives in such a culture.
  +
  +
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.<ref name="worldtrans">{{cite web|url=http://www.worldtrans.org/creators/whale/myths0.html|title=Whale Mythology from around the World|last=Anon|work=The Creative Continuum|publisher=worldtrans.org|accessdate=14 February 2010}}</ref>
  +
  +
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.<ref name="worldtrans"/>
  +
  +
In 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 in the nineteenth year he went fishing and a whale came and killed him.<ref name="worldtrans"/>
  +
  +
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 was still 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.<ref name="worldtrans"/>
  +
  +
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.<ref>{{cite web|title=Whale funeral draws 1000 mourners in Vietnam|url=http://www.smh.com.au/articles/2003/04/13/1050172476288.html|work=AFP|publisher=Sydney Morning Herald|accessdate=15 April 2011}}</ref><ref>{{cite news|title=Thousand gather for whale's funeral in Vietnam|url=http://www.independent.co.uk/news/world/asia/thousand-gather-for-whales-funeral-in-vietnam-1907716.html|agency=Associated Press|publisher=The Independent|accessdate=15 April 2011}}</ref><ref>{{cite web|last=Viegas|first=Jennifer|title=Thousands Mourn Dead Whale in Vietnam|url=http://news.discovery.com/animals/thousands-mourn-dead-whale-in-vietnam.html|work=Discovery News|accessdate=15 April 2011}}</ref><ref>{{cite web|title=Funeral for a Whale held at Apam|url=http://www.ghanaweb.com/GhanaHomePage/NewsArchive/artikel.php?ID=87737|work=Ghana News Agency|publisher=GhanaWeb|accessdate=15 April 2011}}</ref> The whale is a revered creature to Vietnamese fishermen. They are respectfully addressed as "Lord". If one finds a stranded whale corpse, one is in charge of holding the funeral for the "Lord" as if it was one's own parent.
  +
  +
The story of [[Jonah]] being swallowed by a whale also is told in the Qur'an.<ref>{{cite web|url=http://www.arabnews.com/?page=5&section=0&article=121636&d=19&m=4&y=2009|title=Jonah and the Whale|last=Qutb|first=Sayyid|work=Arab news|publisher=Arab News|accessdate=14 February 2010}}</ref>
  +
  +
===Whales in the Bible===
  +
  +
The Bible, 1611 [[Authorized King James Version|Authorized Version]], expressly mentions whales four times:
  +
*[[Book of Genesis|Genesis]] 1:21 And God created great <U>whales</U>, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that ''it was'' good.
  +
*[[Job (biblical figure)|Job]] 7:12 ''Am'' I a sea, or a <U>whale</U>, that thou settest a watch over me?
  +
*[[Ezekiel]] 32:2 Son of man, take up a lamentation for Pharaoh king of Egypt, and say unto him, Thou art like a young lion of the nations, and thou ''art'' as a <U>whale</U> in the seas: and thou camest forth with thy rivers, and troubledst the waters with thy feet, and fouledst their rivers.
  +
*[[Gospel of Matthew|Matthew]] 12:40 For as Jonas was three days and three nights in the <U>whale</U>’s belly; so shall the Son of man be three days and three nights in the heart of the earth.
  +
  +
The translators in that latter verse above thereby identified the "great fish" of the book of [[Jonah]] as a whale. It is apparent that [[Jeremiah]] recognized that some great fish are mammals. The English word "[[Monster (disambiguation)|monster]]", (used in the ordinary sense of a "huge animal",) is used in the Bible in Jeremiah's [[Book of Lamentations|Lamentations]] to refer to whales:
  +
  +
*Lamentations 4:3 Even the sea monsters <U>draw out the breast</U>, they give suck to their young ones: the daughter of my people ''is become'' cruel, like the ostriches in the wilderness.
  +
  +
  +
  +
==See also==
  +
*[[Baleen whale]]
  +
*[[Beached whale]]
  +
*[[Cetacea]]
  +
*[[Cetacean intelligence]]
  +
*[[List of cetaceans]]
  +
*[[List of dolphin species]]
  +
*[[List of porpoise species]]
  +
*[[Toothed whale]]
  +
*[[Vocal learning]]
  +
*[[Whale fall]]
  +
*[[Whale migration]]
  +
*[[Whale watching]]
   
   
 
==References==
  
==References==
−
{{Reflist|2}}
 +
{{Reflist|colwidth=30em}}
   
 
==Further reading==
  
==Further reading==
−
* Carwardine, M., ''Whales, Dolphins and Porpoises'', Dorling Kindersley, 2000. ISBN 0-7513-2781-6
 +
*{{Cite book |last=Carwardine |first=M. |title=Whales, Dolphins and Porpoises |publisher=Dorling Kindersley |year=2000 |isbn=0751327816}}.
−
* [[Heathcote Williams|Williams, Heathcote]], ''Whale Nation'', New York, Harmony Books, 1988. ISBN 9780517569320
 +
*{{Cite book |authorlink=Heathcote Williams |last=Williams |first=Heathcote |title=Whale Nation |location=New York |publisher=Harmony Books |year=1988 |isbn=0517569329}}.
   
 
==External links==
  
==External links==
  +
{{Commons category|Cetacea |Whale}}
 
* [http://wiki.answers.com/Q/FAQ/2915 WikiAnswers: questions and answers about whales]
  
* [http://wiki.answers.com/Q/FAQ/2915 WikiAnswers: questions and answers about whales]
  +
* [http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html Whale Evolution]
  +
* [http://oceans.greenpeace.org/en/our-oceans/whaling Greenpeace work defending whales]
  +
* [http://savethewhales.org/stwsong_hi.html Save the Whales, founded in 1977]
 
* [http://aquaticmammals.org AquaNetwork Marine Mammal Project]
  
* [http://aquaticmammals.org AquaNetwork Marine Mammal Project]
  +
* [http://www.life.com/image/first/in-gallery/37242/whales-in-the-wild#index/0 Whales in the Wild] – slideshow by ''[[Life magazine]]''
−
* [http://www.wdcs.org/ Whale and Dolphin Conservation Society - latest news and information on whales and dolphins]
  
  +
* [http://news.bbc.co.uk/1/hi/sci/tech/239966.stm Oldest whale fossil confirms amphibious origins]
  +
* [http://www.sciencedaily.com/news/plants_animals/dolphins_and_whales/ Research on dolphins and whales from Science Daily]
  +
* [http://www.wdcs.org/ Whale and Dolphin Conservation Society – latest news and information on whales and dolphins]
  +
* [http://www.oceania.org.au/ The Oceania Project – Caring for whales and dolphins]
  +
* [http://collections.tepapa.govt.nz/exhibitions/whales/ Whales Tohorā Exhibition Minisite from the Museum of New Zealand Te Papa Tongarewa]
  +
* [http://www.teara.govt.nz/EarthSeaAndSky/SeaLife/Whales/en Whales in Te Ara the Encyclopedia of New Zealand]
  +
* [http://www.squidforce.com/tag/whales/ Orca and other whales video at Squid Force]
  +
* [http://www.whales.org.za www.whales.org.za Whales information portal]
  +
*[http://www.panda.org/what_we_do/endangered_species/endangered_species_list/cetaceans/ World Wide Fund for Nature (WWF) – information on whales, dolphins, and porpoises]
  +
*[http://www.whaletrackers.com Whale Trackers – An online documentary series about whales, dolphins and porpoises]
  +
*[https://www.youtube.com/watch?v=tcXU7G6zhjU&feature=player_embedded#at=163 A whale being freed from netting (YouTube video).]
  +
  +
{{Cetacea|M.}}
   
   
   
 
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Latest revision as of 16:51, 19 November 2011

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?Whale
North Atlantic right whales, mother and calf
North Atlantic right whales, mother and calf
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetacea

Whale (origin Old English hƿæl) 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,[2] which belong to suborder Odontoceti (toothed whales). This suborder also includes the sperm whale, killer whale, pilot whale, and beluga whale. The other Cetacean suborder Mysticeti (baleen whales) are filter feeders that eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the blue whale, the humpback whale, the bowhead whale and the minke whale. All Cetacea 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[3] at Template:Convert/LoffAonDbSoffTemplate:Convert/test/Aon and Template:Convert/tTemplate:Convert/test/A, to various pygmy species, such as the pygmy sperm whale at Template:Convert/LoffAonDbSoffTemplate:Convert/test/Aon.

Whales collectively 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%.[4] For centuries, whales have been hunted for meat and as a source of raw materials. By the middle of the 20th century, however, industrial whaling had left many species seriously endangered, leading to the end of whaling in all but a few countries.

Taxonomy

See also: List of whale species

Cetaceans are divided into two suborders:

  • The largest suborder, Mysticeti (baleen whales) are characterized by 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 also include dolphins and porpoises.

Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippopotamuses. Whales are the hippopotamus's closest living relatives.[5]

Evolution

File:Ambulocetus BW.jpg

Ambulocetus natans – a primitive whale

See also: Evolution of cetaceans

All cetaceans, including whales, dolphins and porpoises, are descendants of land-living 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 around 54 million years ago.[6][7] Primitive whales probably first took to the sea about 50 million years ago and became fully aquatic about 5–10 million years later.[8]

Anatomy

Like all mammals, whales breathe air, are warm-blooded, nurse their young with milk from mammary glands, and have body hair.[citation needed]

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. The neck vertebrae are typically fused, trading flexibility for stability during swimming.[citation needed]

Blowhole(s)

File:Baleen parts.png

Features of a blue whale

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 mostly submerged whilst breathing. Breathing involves expelling excess water from the blowhole, forming an upward spout, followed by inhaling air into the lungs. Spout shapes differ among species and can help with 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 even have feet and digits. Most species have a dorsal fin.[citation needed]

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 has been worn away on the tip of the tooth, does enamel show.[9]

Instead of teeth, Baleen whales have a row of 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 matcher between the outside air’s low impedance and the cochlear fluid’s high impedance. In aquatic mammals such as whales, however, 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.[10] The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. [11]

Life history/behavior

Reproduction

Males are called 'bulls', females, 'cows' and newborns, 'calves'. Most species do not maintain fixed partnerships and females have several mates each season.[12][13]

The female delivers usually a single calf tail-first to minimize the risk of drowning. Whale cows nurse by actively squirting milk, so fatty that it has the consistency of toothpaste, into the mouths of their young.[12] Nursing continues for more than a year in many species, and is associated with a strong bond between mother and calf. Reproductive maturity occurs typically at seven to ten years. This mode of reproduction produces few offspring, but increases survival probability.

Socialization

Whales are known to teach, learn, cooperate, scheme, and even grieve.[14] The neocortex of many species of whale is home to elongated spindle neurons that, prior to 2007, were known only in hominids.[15] In humans these cells are involved in social conduct, emotions, judgment, and theory of mind.[16] Whale spindle neurons are found in areas of the brain homologous to where they are found in humans, suggesting that they perform a similar function. [17]

Sleep

File:Humpback stellwagen edit.jpg

A Humpback Whale breaching.

Unlike most animals, whales are conscious breathers. All mammals sleep, but whales cannot afford to become unconscious for long because they may drown. It is thought that only one hemisphere of the whale's brain sleeps at a time, so they rest but are never completely asleep.[18]

Surfacing behavior

Main article: Whale surfacing behavior

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

Lifespan

Whale lifespans vary among species and are not well characterized. Whaling left few older individuals to observe directly. R.M. Nowak of Johns Hopkins University estimated that humpback whales may live as long as 77 years.[19] In 2007, a 19th century lance fragment was found in a bowhead whale off Alaska, suggesting the individual could be between 115 and 130 years old.[20] 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.[21][22] The accuracy of this technique has been questioned because racemization did not correlate well with other dating methods.[23]

Vocalization

Some species, such as the humpback whale, communicate using melodic sounds, known as whale song. These sounds can be extremely loud, depending on the species. Sperm whales have only been heard making clicks, while toothed whales (Odontoceti) use echolocation that can generate about 20,000 watts of sound (+73 dBm or +43 dBw[24]) and be heard for many miles. Whale vocalization is likely to serve many purposes, including echolocation, mating, and identification.[citation needed]

Ecology

Feeding

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

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

Baleen whales such as humpbacks and blues feed only in arctic waters, eating mostly krill. They imbibe enormous amounts of seawater which they expel through their baleen plates. The water is then expelled and the krill is retained on the plates and then swallowed.[12] Whales do not drink seawater but indirectly extract water from their food by metabolizing fat.[12]


Naval sonar

See also: Marine Mammals and 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 to signs that such whales have experienced decompression sickness.[25] Responses in Nature the following year discounted the explanation.[26]

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 over the last 1,000 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.[14]

Following public concern, the U.S. Defense department was ordered by the 9th Circuit Court 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) failed as of 2008. The European Parliament has requested that EU members refrain from using the powerful sonar system until an environmental impact study has been carried out.


In mythology

File:Nantucket historical assocation whaling museum weather vane.jpg

Whale weather-vane atop the Nantucket Historical Association Whaling Museum displaying a Sperm Whale.

Whales were little understood for most of human history as they spend up to 90% of the lives underwater, only surfacing briefly to breathe.[27] They also include the largest animals on the planet, so it is not surprising that many cultures, even those that have hunted them, hold them in awe and feature them in their mythologies.

In China, Yu-kiang, a whale with the hands and feet of a man was said to rule the ocean.[28]

In the Tyrol region of Austria it was said that if a sunbeam were to fall on a maiden entering womanhood, she would be carried away in the belly of a whale.[28]

Paikea, the youngest and favourite son of the chief Uenuku from the island of Mangaia in the present day Cook Islands in New Zealand was said by the Kati Kuri people of Kaikoura to have come from the Pacific Islands on the back of a whale many centuries before.[29] The novel and movie Whale Rider follow the trials of a girl named Paikia, who lives in such a culture.

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.[30]

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.[30]

In 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 in the nineteenth year he went fishing and a whale came and killed him.[30]

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 was still 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.[30]

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.[31][32][33][34] The whale is a revered creature to Vietnamese fishermen. They are respectfully addressed as "Lord". If one finds a stranded whale corpse, one is in charge of holding the funeral for the "Lord" as if it was one's own parent.

The story of Jonah being swallowed by a whale also is told in the Qur'an.[35]

Whales in the Bible

The Bible, 1611 Authorized Version, expressly mentions whales four times:

  • Genesis 1:21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.
  • Job 7:12 Am I a sea, or a whale, that thou settest a watch over me?
  • Ezekiel 32:2 Son of man, take up a lamentation for Pharaoh king of Egypt, and say unto him, Thou art like a young lion of the nations, and thou art as a whale in the seas: and thou camest forth with thy rivers, and troubledst the waters with thy feet, and fouledst their rivers.
  • Matthew 12:40 For as Jonas 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.

The translators in that latter verse above thereby identified the "great fish" of the book of Jonah as a whale. It is apparent that Jeremiah recognized that some great fish are mammals. The English word "monster", (used in the ordinary sense of a "huge animal",) is used in the Bible in Jeremiah's Lamentations to refer to whales:

  • Lamentations 4:3 Even the sea monsters draw out the breast, they give suck to their young ones: the daughter of my people is become cruel, like the ostriches in the wilderness.


See also


References

  1. ↑ (2007) Brown, Lesley Shorter Oxford English Dictionary, Sixth, Oxford: Oxford University press.
  2. ↑ ACS – American Cetacean Society. Acsonline.org. Retrieved on 2011-11-18.
  3. ↑ What is the biggest animal ever to exist on Earth?. How Stuff Works. URL accessed on 2007-05-29.
  4. ↑ Whale Population Estimates. International Whaling Commission. URL accessed on March 2010.
  5. ↑ Anon Scientists find missing link between the whale and its closest relative, the hippo. PhysOrg.com. PhysOrg.com. URL accessed on 6 May 2010.
  6. ↑ Northeastern Ohio Universities Colleges of Medicine and Pharmacy. Whales Descended From Tiny Deer-like Ancestors. ScienceDaily. URL accessed on 2007-12-21.
  7. ↑ Dawkins, Richard (2004). The Ancestor's Tale, Boston: Houghton Mifflin Company.
  8. ↑ includeonly>"How whales learned to swim", BBC News, 2002-05-08. Retrieved on 2006-08-20.
  9. ↑ "Common Characteristics of Whale Teeth" here [1]
  10. ↑ How is that whale listening?. URL accessed on February 4, 2008.
  11. ↑ Nummela, Sirpa. (2007). Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing.. The Anatomical Record 290 (6): 716–733.
  12. ↑ 12.0 12.1 12.2 12.3 Blue Whale.
  13. ↑ "Milk". Modern Marvels. The History Channel. 2008-01-07.
  14. ↑ 14.0 14.1 includeonly>Siebert, Charles. "Watching Whales Watching Us", New York Times Magazine, July 8, 2009.
  15. ↑ cite journal |author=Watson, K.K. | title=Dendritic architecture of the Von Economo neurons | journal= Neuroscience | volume= 141 |issue=3 |pages= 1107–1112 |year=2006 |doi=10.1016/j.neuroscience.2006.04.084 |last2=Jones |first2=T.K. |last3=Allman |first3=J.M.}}
  16. ↑ Allman, John M. (2005). Intuition and autism: a possible role for Von Economo neurons. Trends Cogn Sci 9 (8): 367–373.
  17. ↑ Hof, Patrick R. (2007). Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae). The Anatomical Record 290 (1): 1–31.
  18. ↑ Anon Do whales and dolphins sleep?. How Stuff Works. Discovery Communications. URL accessed on 14 February 2010.
  19. ↑ Anon (2005). Humpback Whale. Animal Infor. Animal Info. URL accessed on 25 February 2010.
  20. ↑ includeonly>Conroy, Erin. "Netted whale hit by lance a century ago", June, 2007. Retrieved on 2009-10-05.
  21. ↑ Bowhead Whales May Be the World's Oldest Mammals. URL accessed on 2008-03-25.
  22. ↑ George, J.C. (1999). Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization. Can. J. Zool. 77 (4): 571–580.
  23. ↑ Brignole, Edward, McDowell, Julie Amino Acid Racemization. Today's chemist at work. American Chemical Society. URL accessed on 25 February 2010.
  24. ↑ dBm – dBw Watts conversion chart, Radio-Electronics.com
  25. ↑ includeonly>"Sonar may cause Whale deaths", BBC News, 2003-10-08. Retrieved on 2006-09-14.
  26. ↑ Piantadosi CA, Thalmann ED (2004-04-15). Pathology: whales, sonar and decompression sickness. Nature 428 (6894): 716–718.
  27. ↑ Bird, Jonathon Sperm Wales:The deep rivers of the ocena. The Wonders of the Seas. jonathon.bird.org. URL accessed on 14 February 2010.
  28. ↑ 28.0 28.1 Jones, Adair In search of . . . whales in literature. Wordpress.com. wordpress. URL accessed on 14 February 2010.
  29. ↑ Anon Whales. Tinirau education resource. URL accessed on 14 February 2010.
  30. ↑ 30.0 30.1 30.2 30.3 Anon Whale Mythology from around the World. The Creative Continuum. worldtrans.org. URL accessed on 14 February 2010.
  31. ↑ Whale funeral draws 1000 mourners in Vietnam. AFP. Sydney Morning Herald. URL accessed on 15 April 2011.
  32. ↑ includeonly>"Thousand gather for whale's funeral in Vietnam", The Independent. Retrieved on 15 April 2011.
  33. ↑ Viegas, Jennifer Thousands Mourn Dead Whale in Vietnam. Discovery News. URL accessed on 15 April 2011.
  34. ↑ Funeral for a Whale held at Apam. Ghana News Agency. GhanaWeb. URL accessed on 15 April 2011.
  35. ↑ Qutb, Sayyid Jonah and the Whale. Arab news. Arab News. URL accessed on 14 February 2010.

Further reading

  • Carwardine, M. (2000). Whales, Dolphins and Porpoises, Dorling Kindersley..
  • Williams, Heathcote (1988). Whale Nation, New York: Harmony Books..

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