Difference between revisions of "Blubber" - New World Encyclopedia

From New World Encyclopedia
m (Protected "Blubber": Copyedited [edit=sysop:move=sysop])
 
(10 intermediate revisions by 2 users not shown)
Line 1: Line 1:
−
[[Image:Whale blubber.jpg|thumb|right|200px|Whale blubber.]]
+
{{Copyedited}}{{Images OK}}{{Approved}}
−
'''Blubber''' is a thick, dense layer of highly organized [[connective tissue]] with a lot of [[fat cell]]s found under the skin of all [[cetacean]]s ([[whale]]s, [[dolphin]]s, and [[porpoise]]s), [[pinniped]]s ([[walrus]]es, [[earless seal]]s, and [[eared seal]]s), and [[sirenian]]s ([[manatee]]s and [[dugong]]s). Of the four groups of [[marine mammal]]s, only the [[sea otter]]s lack blubber. [[Polar bear]]s, which some include with the marine mammals, also have blubber. Blubber provides insulation for these [[warm-blooded]] animals, as well as functions as an energy reserve and streamlines the body, while the elastic fibers contained in blubber helps in swimming.
+
[[Image:Whale blubber.jpg|thumb|right|240px|Whale blubber]]
 +
'''Blubber''' is a thick, dense layer of highly organized [[connective tissue]] with a lot of [[fat cell]]s found under the skin of all [[cetacean]]s ([[whale]]s, [[dolphin]]s, and [[porpoise]]s), [[pinniped]]s ([[walrus]]es, [[earless seal]]s, and [[eared seal]]s), and [[sirenian]]s ([[manatee]]s and [[dugong]]s). Of the four groups of [[marine mammal]]s, only the [[sea otter]]s lack blubber. [[Polar bear]]s, which some also include with the marine mammals, also have blubber. Blubber provides insulation for these [[warm-blooded]] animals, as well as functions as an [[energy]] reserve and streamlines the body, while the elastic fibers contained in blubber may help in swimming.
  
−
This [[adaptation]] of blubber, which is so important for marine mammals, also has been of historical importance for humans....
+
This [[adaptation]] of blubber, which is so important for marine mammals, also has been of historical importance for humans. People in northern regions have relied upon it as a high-energy [[food]] and the rich [[oil]] obtained from blubber was a key reason for the [[whaling]] trade. Oil form blubber was used as fuel for lamps, used in making candles, and employed in the manufacture of [[soap]], cosmetics, machinery lubricants, and so forth.
  
 
==Overview and description==
 
==Overview and description==
−
Blubber is composed of [[connective tissue]] fibers and vascularized [[fat]] found between the muscles and skins of particular [[marine mammal]]s. The connective tissue is made of [[collagen]], as is found in human connective tissue. [[Lipid]]-rich, collagen fiber-laced blubber comprises the [[hypodermis]] (Struntz et al. 2004), the lowermost layer of the integumentry system in vertebrates, lying immediately below the dermis of the vertebrate skin. The hypodermis consists primarily of loose connective tissue and lobules of fat, and typically has larger blood vessels and nerves than in the dermis. Blubber covers the whole body, except for parts of the appendages, and is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligaments. Blubber is more vascularized, or rich in blood vessels, than other adipose tissue.
+
Blubber is composed of [[connective tissue]] fibers and vascularized [[fat]] found between the muscles and skins of particular [[marine mammal]]s. The connective tissue is made of [[collagen]], as is found in human connective tissue. [[Lipid]]-rich, collagen fiber-laced blubber comprises the [[hypodermis]] (Struntz et al. 2004), the lowermost layer of the integumentry system in [[vertebrate]]s, lying immediately below the dermis of the vertebrate skin. The hypodermis consists primarily of loose connective tissue and lobules of fat, and typically has larger blood vessels and nerves than in the dermis. Blubber covers the whole body, except for parts of the appendages, and is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligaments. Blubber is more vascularized, or rich in blood vessels, than other adipose tissue.  
  
−
Blubber can comprise a substantial portion of the body mass of marine mammals. Generally, the blubber layer of the bottlenose dolphin accounts for about 18 percent to 20 percent of its body weight (SW/BG; Bryden and Harrison 1986). It may comprise up to fifty percent of the body weight of some marine mammals (Smith 2009) during some points in their lives (Smith 2009).
+
Blubber can comprise a substantial portion of the body mass of marine mammals. Generally, the blubber layer of the bottlenose dolphin accounts for about 18 to 20 percent of its body weight (SW/BG 2002a; Bryden and Harrison 1986). It may comprise up to fifty percent of the body weight of some marine mammals (Smith 2009) during some points in their lives (Smith 2009).
  
−
Blubber can range from a couple of inches thick in dolphins and smaller whales, to up to 4.3 inches (11 centimeters) thick in [[polar bear]]s (Stirling 1988), to more than a foot thick in some bigger whales, such as [[Right Whales|right]] and [bowhead whales]]. However, this thicker layer of blubber is not indicative of larger whales' ability to retain heat better, as the thickness of a whale's blubber does not significantly affect heat loss. More indicative of a whale's ability to retain heat is the water and lipid concentration in blubber, as water reduces heat retaining capacities, and lipid increases them (Kvadsheim et al. 1996).  
+
Blubber can range from a couple of inches thick in [[dolphin]]s and smaller whales, to up to 4.3 inches (11 centimeters) thick in [[polar bear]]s (Stirling and Guravich 1988; SW/BG 2002b), to more than a foot thick in some bigger whales, such as [[Right Whales|right]] and [[bowhead whales]]. However, this thicker layer of blubber is not indicative of larger whales' ability to retain [[heat]] better, as the thickness of a whale's blubber does not significantly affect heat loss. More indicative of a whale's ability to retain heat is the water and lipid concentration in blubber, as water reduces heat retaining capacities, and lipid increases them (Kvadsheim et al. 1996).  
  
 
==Function==
 
==Function==
−
Blubber serves several different functions. It is the primary location of fat on some [[mammal]]s, and is essential for '''storing energy'''. When food resources are scarce, these layers of blubber with their fat deposits can be used for food and replaced when food is more easily obtained. Blubber is particularly important for species that feed and breed in different parts of the ocean. During these, periods the species are operating on a fat-based [[metabolism]].
+
Blubber serves several different functions. It is the primary location of fat on some [[mammal]]s, and is essential for '''storing energy'''. When food resources are scarce, these layers of blubber with their fat deposits can be used for food and replaced when food is more easily obtained. Blubber is particularly important for species that feed and breed in different parts of the ocean. During these, periods the species are operating on a fat-based [[metabolism]].  
  
−
Blubber is, however, different from other forms of [[adipose tissue]] in its extra thickness, which allows it to serve as an efficient thermal [[Thermal insulation|insulator]], making blubber essential for '''[[thermoregulation]]''', particularly in marine mammals in extreme cold environments. Since heat loss is greater in water than in air, it is vital that warm-blooded animals in cold aquatic environments have a means to retrain heat. Blubber helps to insulate them from the cold. In the bottlenose dolphin, which has a core temperature of about 98.4°F (36.9°C), a heat gradient is seen throughout the blubber to the skin (Ridgway 1972).
+
Blubber is, however, different from other forms of [[adipose tissue]] in its extra thickness, which allows it to serve as an efficient thermal [[Thermal insulation|insulator]], making blubber essential for '''[[thermoregulation]]''', particularly in marine mammals in extreme cold environments. Since heat loss is greater in water than in air, it is vital that warm-blooded animals in cold aquatic environments have a means to retrain heat. Blubber helps to insulate them from the cold. In the bottlenose dolphin, which has a core [[temperature]] of about 98.4°F (36.9°C), a heat gradient is seen throughout the blubber to the skin (Ridgway 1972).
  
 
Blubber has advantages over [[fur]] (as in [[sea otter]]s) in the respect that although fur can retain heat by holding pockets of air, the air pockets will be expelled under pressure (while diving). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as -40 degrees Fahrenheit. While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator (Galbraith et al. 2001).  
 
Blubber has advantages over [[fur]] (as in [[sea otter]]s) in the respect that although fur can retain heat by holding pockets of air, the air pockets will be expelled under pressure (while diving). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as -40 degrees Fahrenheit. While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator (Galbraith et al. 2001).  
Line 22: Line 23:
 
Blubber also may save further energy for marine mammals such as dolphins in that it '''aids swimming''' by adding a bounce to the movement. The blubber between the tail flukes and a dolphin's top dorsal fin is crosshatched with elastic fibers that add a spring to the dolphin's strokes. Essentially, the animal is bouncing on a blubber spring, decreasing the amount of energy needed to swim fast (Hirshon and Pabst 2000).  
 
Blubber also may save further energy for marine mammals such as dolphins in that it '''aids swimming''' by adding a bounce to the movement. The blubber between the tail flukes and a dolphin's top dorsal fin is crosshatched with elastic fibers that add a spring to the dolphin's strokes. Essentially, the animal is bouncing on a blubber spring, decreasing the amount of energy needed to swim fast (Hirshon and Pabst 2000).  
  
−
Research into the thermal conductivity of [[bottlenose dolphin|the common bottlenose dolphin]]'s blubber reveals that its thickness varies greatly amongst individuals (Dunkin et al. 2005). However, blubber from emaciated dolphins is much worse of an insulator than that of non-pregnant adults, which in turn have a higher heat conductivity than blubber from pregnant females and pre-adults. Maternal care is extremely important to the survival of offspring that need to develop a thick insulating layer of blubber. The milk from the mammary glands of marine mammals often exceeds forty to fifty percent fat content to support the development of blubber in the young.
+
Research into the thermal conductivity of [[bottlenose dolphin|the common bottlenose dolphin]]'s blubber reveals that its thickness varies greatly amongst individuals (Dunkin et al. 2005). However, blubber from emaciated dolphins is much worse of an insulator than that of non-pregnant adults, which in turn have a higher heat conductivity than blubber from pregnant females and pre-adults. Maternal care is extremely important to the survival of offspring that need to develop a thick insulating layer of blubber. The milk from the mammary glands of marine mammals often exceeds forty to fifty percent fat content to support the development of blubber in the young.
  
−
==Human Influences==
+
==Human influences==
 
===Uses===
 
===Uses===
−
[[Muktuk]], (the Inuit/Eskimo word for blubber) formed an important part of the traditional diets of the [[Inuit]] and other northernly peoples because of its high energy value.<ref name="ref1">{{cite web | url= http://www.wisegeek.com/what-is-blubber.htm | title= What is Blubber?}}</ref>  Seal blubber has large amounts of [[Vitamin E]], [[selenium]], and other [[anti-oxidants]] that hinder oxidation, which slows the formation of the [[free radical]]s that start a wide variety of diseases.  The positive effects of consuming blubber can be seen in Greenland; in [[Uummannaq]] for example, a hunting district with 3000 residents, no deaths due to cardiovascular diseases occurred in the 1970s.  However, emigrants to Denmark have contracted the same diseases as the rest of the population.  The average 70-year-old Inuit with a traditional diet of whale and seal has arteries as elastic as that of a 20-year-old Danish resident. <ref>{{cite web | url= http://www.highnorth.no/Library/Culture/or-ea-me.htm| title= Orsoq - Eat Meat and Blubber from Sea Mammals and avoid Cardiovascular disease.}}</ref>
+
Blubber has been used extensively by people for fool and fuel, among other purposes.
  
−
One of the major reasons for the [[whaling]] trade was the collection of whale blubber. This was rendered down into [[whale oil|oil]] in [[try pot]]s or later, in vats on factory ships. The oil could be then used in the manufacture of soap, leather, and cosmetics.<ref>{{cite encyclopedia | last = Donovan | first = Greg | title = Whaling | encyclopedia = Microsoft Encarta | date = 2008}}</ref>  Whale oil was also used in candles as wax, and in [[oil lamps]] as fuel.
+
Blubber provides a high-energy food. [[Muktuk]], the Inuit/Eskimo word for blubber, formed an important part of the traditional diets of the [[Inuit]] and other northernly peoples because of its high energy value (Smith 2009). Seal blubber also has large amounts of [[vitamin E]], [[selenium]], and other [[antioxidant]]s that hinder oxidation, thus slowing the formation of the [[free radical]]s that start a wide variety of [[disease]]s. The possible positive effects of consuming blubber may be seen in [[Greenland]]; in [[Uummannaq]] for example, a hunting district with 3000 residents, no deaths due to cardiovascular diseases occurred in the 1970s. However, emigrants to Denmark have contracted the same diseases as the rest of the population. Mulvad and Pedersen (1992) report that the average 70-year-old Inuit with a traditional diet of whale and seal has arteries as elastic as that of a 20-year-old Danish resident (Mulvad and Pedersen 1992).
  
−
Blue whales can yield blubber harvests up to 50 tons. <ref>{{cite encyclopedia | title = Cetacean | encyclopedia = Encyclopædia Britannica. Ultimate Reference Suite | date = 2008}}</ref>
+
One of the major reasons for the [[whaling]] trade was the collection of whale blubber. This was rendered down into [[whale oil|oil]] in [[try pot]]s or later, in vats on factory ships. This rich oil could be then used in the manufacture of soap, leather, and cosmetics (Donovan 2008). Whale oil was also used in candles as wax, and in [[oil lamps]] as fuel, and as lubricants for machinery.
 +
 
 +
Blue whales can yield blubber harvests up to 50 tons.  
  
 
===Toxicity===
 
===Toxicity===
  
−
Recent studies suggest that blubber contains naturally occurring [[Polychlorinated biphenyl|PCB]], which are cancer causing and damage the human nervous, immune and reproductive systems. <ref>{{cite web | url= http://www.sciencedaily.com­/releases/2005/02/050213132247.htm | title=Chemical Compounds Found In Whale Blubber Are From Natural Sources, Not Industrial Contamination
+
Studies of blubber in recent years suggest that blubber contains naturally occurring [[Polychlorinated biphenyl|PCB]], which are cancer causing and damage the human nervous, immune, and reproductive systems (WHOI 2005). It is not known where the source of this PCB is. Since [[toothed whale]]s typically place high on the food chain, they are bound to consume large amounts of industrial pollutants. Even [[baleen whale]]s, by merit of the huge amount of food they consume, are bound to have toxic chemicals stored in their bodies. Recent studies have found high levels of [[mercury]] in the blubber of seals of the Canadian Arctic.
−
}}</ref><ref>{{cite web | url=http://news.bbc.co.uk/2/hi/science/nature/1132889.stm | title=Japan warned on 'contaminated' blubber}}</ref>. It is not known where the source of this PCB is. Since toothed whales typically place high on the food chain, they are bound to consume large amounts of industrial pollutants. Even baleen whales, by merit of the huge amount of food they consume, are bound to have toxic chemicals stored in their bodies. Recent studies have found high levels of mercury in the blubber of seals of the Canadian Arctic.
 
−
 
 
−
==Works Cited==
 
−
{{reflist}}
 
  
 
==References==
 
==References==
  
−
Bryden, M.M. and Richard Harrison, eds. Research on Dolphins. New York: Oxford University Press, 1986.
+
* Athropolis. n.d. [http://www.athropolis.com/arctic-facts/fact-blubber-whale.htm Facts: Cold, icy, and arctic] ''Athropolis''. Retrieved February 14, 2009.
−
 
+
* Bryden, M.M., and R. Harrison (eds). 1986. ''Research on Dolphins''. New York: Oxford University Press. ISBN 0198576064.
−
<ref>{{cite web | author= Dunkin, Robin et al| title="The ontogenetic changes in the thermal properties of blubber from Atlantic bottlenose dolphin Tursiops truncatus" | publisher=''Journal of Experimental Biology'' | accessdate=03-05-2005 | url= http://jeb.biologists.org/cgi/content/abstract/208/8/1469}}</ref>
+
* Donovan, G. 2008. Whaling. ''Microsoft Encarta''. 
−
The ontogenetic changes in the thermal properties of blubber from Atlantic bottlenose dolphin Tursiops truncatus
+
* Dunkin, R.C., W.A. McLellan, J.E. Blum, and D.A. Pabst. 2005. [http://jeb.biologists.org/cgi/content/abstract/208/8/1469 The ontogenetic changes in the thermal properties of blubber from Atlantic bottlenose dolphin "Tursiops truncatus"] ''Journal of Experimental Biology'' 208: 1469-1480. Retrieved February 14, 2009.
−
Robin C. Dunkin1, William A. McLellan1, James E. Blum2 and D. Ann Pabst
+
* Galbraith, D. I., and L. Blake, et al. 2001. ''McGraw-Hill Ryerson Biology 11''. Whitby, Ont: McGraw-Hill Ryerson. OCLC 51175612.
−
Journal of Experimental Biology 208, 1469-1480 (2005)
+
* Hirshon, B., and A. Pabst. 2000. [http://www.sciencenetlinks.com/sci_update.cfm?DocID=10 Bouncy blubber] ''Science NetLinks'' November 15, 2000. Retrieved February 14, 2009.
−
 
+
* Kvadsheim, P.H., L.P. Folkow, and A.S. Blix. 1996. [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T94-3VXJG51-9&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=2119bcbbf8b3ad5a33f85f247c1b530e Thermal conductivity of minke whale blubber] ''Journal of Thermal Biology'' 21(2): 123-128. Retrieved February 14, 2009.
−
 
+
* Marine Mammal Center (MMC). n.d. [http://www.marinemammalcenter.org/learning/education/teacher_resources/blubber.asp Education resources for teachers: Blubber experiment] ''Marine Mammal Center''. Retrieved February 14, 2009.
−
 
+
* Mulvad, G., and H.S. Pedersen. 1992. [http://www.highnorth.no/Library/Culture/or-ea-me.htm Orsoq: Eat meat and blubber from sea mammals and avoid cardiovascular disease] ''Inuit Whaling'' June 1992, Special Issue. Retrieved February 14, 2009.
−
#{{cite web
+
* Ridgway, S. 1972. ''Mammals of the Sea. Biology and Medicine''. Springfield, IL: Charles C. Thomas. Retrieved February 14, 2009.  
−
  | url= http://www.marinemammalcenter.org/learning/education/teacher_resources/blubber.asp
+
* SeaWorld/Busch Gardens (SW/BG). 2002a. [http://www.buschgardens.org/infobooks/Bottlenose/adapaqdol.html Adaptations for an aquatic environment] ''SeaWorld/Busch Gardens Animal Information Database''. Retrieved February 14, 2009.
−
  | title= Education Resources for Teachers—Blubber Experiment}}
+
* &mdash;&mdash;&mdash;. 2002b. [http://www.seaworld.org/infobooks/polarbears/pbadaptations.html Polar bears] ''SeaWorld/Busch Gardens Animal Information Database''. Retrieved February 14, 2009.
−
http://www.tmmc.org/learning/education/teacher_resources/blubber.asp
+
* Smith, S.E. 2009. [http://www.wisegeek.com/what-is-blubber.htm What is blubber?] ''WiseGeek''. February 14, 2009.  
−
MMC
+
* Stirling, I., and D. Guravich.1988. ''Polar Bears''. Ann Arbor, MI: The University of Michigan Press. ISBN 0472101005.
−
n.d.
+
* Struntz, D.J., W.A. McLellan, R.M. Dillaman, J.E. Blum, J.R. Kucklick, and D.A. Pabst. 2004. [http://www.ncbi.nlm.nih.gov/pubmed/14666521?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum Blubber development in bottlenose dolphins "(Tursiops truncatus)"] "J Morphol." 259(1): 7-20. Retrieved February 14, 2009.
−
 
+
* Woods Hole Oceanographic Institution (WHOI). 2005. [http://www.sciencedaily.com­/releases/2005/02/050213132247.htm Chemical compounds found in whale blubber are from natural sources, not industrial contamination] ''ScienceDaily''. Retrieved February 14, 2009/
−
 
 
−
 
 
−
#{{cite web
 
−
  | url= http://www.athropolis.com/arctic-facts/fact-blubber-whale.htm
 
−
  | title= Arctic Facts-Blubber}}
 
−
http://www.athropolis.com/arctic-facts/fact-blubber-whale.htm Facts: Cold, Icy, and Arctic.
 
−
 
 
−
 
 
−
thick layer of [[Blood vessel|vascularized]] [[fat]] found under the skin of all [[cetacean]]s, [[pinniped]]s and [[sirenian]]s.<ref name="ref1">{{cite web | url= http://www.wisegeek.com/what-is-blubber.htm | title= What is Blubber?}}</ref>
 
−
S.E. Smith
 
−
copyright © 2003 - 2009
 
−
 
 
−
Galbraith, Donald I., and Lessa Blake. et al. 2001. McGraw-Hill Ryerson biology 11. Whitby, Ont: McGraw-Hill Ryerson.  
 
−
<ref>Don Galbraith et al. ''Biology 11.'' (Canada: McGraw-Hill Ryerson). pg. 12.</ref>  OCLC 51175612.
 
−
 
 
−
 
 
−
Bob Hirshon
 
−
Ann Pabst
 
−
http://www.sciencenetlinks.com/sci_update.cfm?DocID=10 Bouncy Blubber
 
−
Science NetLinks
 
−
11/15/2000
 
−
 
 
−
a dolphin's swim<ref>{{cite web| url= http://www.sciencenetlinks.com/sci_update.cfm?DocID=10 |title= Science Update—Bouncy Blubber}}</ref>.
 
−
 
 
−
.<ref>{{cite web | author=P. H. Kvadsheim, a, b, , L. P. Folkowb, a and A. S. Blixb, a | url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T94-3VXJG51-9&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=2119bcbbf8b3ad5a33f85f247c1b530e | title=Thermal conductivity of minke whale blubber}}</ref>
 
−
Journal of Thermal Biology
 
−
Volume 21, Issue 2, April 1996, Pages 123-128  
 
−
 
 
−
Ridgway, Sam. Mammals of the Sea. Biology and Medicine. Springfield, Illinois: Charles C. Thomas, 1972.
 
−
 
 
−
 
 
−
SeaWorld/Busch Gardens Animal Information Database
 
−
http://www.buschgardens.org/infobooks/Bottlenose/adapaqdol.html
 
−
Adaptations for an Aquatic Environment
 
−
2002
 
−
<ref name="ref1">{{cite web | url= http://www.wisegeek.com/what-is-blubber.htm | title= What is Blubber?}}</ref>
 
−
 
 
−
 
 
−
http://www.seaworld.org/infobooks/polarbears/pbadaptations.html
 
−
Polar bears
 
−
2002
 
−
 
 
−
Stirling, Ian. Polar Bears. Ann Arbor: The University of Michigan Press, 1988.  
 
−
 
 
−
 
 
−
<ref>Struntz DJ et al. "Blubber development in bottlenose dolphins (Tursiops truncatus)." PubMed. From http://www.ncbi.nlm.nih.gov/pubmed/14666521?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum
 
−
 
 
−
J Morphol. 2004 Jan;259(1):7-20.Click here to read Links
 
−
    Blubber development in bottlenose dolphins (Tursiops truncatus).
 
−
    Struntz DJ, McLellan WA, Dillaman RM, Blum JE, Kucklick JR, Pabst DA.
 
−
 
 
  
 
{{Whaling}}
 
{{Whaling}}

Latest revision as of 03:45, 16 February 2009

Whale blubber

Blubber is a thick, dense layer of highly organized connective tissue with a lot of fat cells found under the skin of all cetaceans (whales, dolphins, and porpoises), pinnipeds (walruses, earless seals, and eared seals), and sirenians (manatees and dugongs). Of the four groups of marine mammals, only the sea otters lack blubber. Polar bears, which some also include with the marine mammals, also have blubber. Blubber provides insulation for these warm-blooded animals, as well as functions as an energy reserve and streamlines the body, while the elastic fibers contained in blubber may help in swimming.

This adaptation of blubber, which is so important for marine mammals, also has been of historical importance for humans. People in northern regions have relied upon it as a high-energy food and the rich oil obtained from blubber was a key reason for the whaling trade. Oil form blubber was used as fuel for lamps, used in making candles, and employed in the manufacture of soap, cosmetics, machinery lubricants, and so forth.

Overview and description

Blubber is composed of connective tissue fibers and vascularized fat found between the muscles and skins of particular marine mammals. The connective tissue is made of collagen, as is found in human connective tissue. Lipid-rich, collagen fiber-laced blubber comprises the hypodermis (Struntz et al. 2004), the lowermost layer of the integumentry system in vertebrates, lying immediately below the dermis of the vertebrate skin. The hypodermis consists primarily of loose connective tissue and lobules of fat, and typically has larger blood vessels and nerves than in the dermis. Blubber covers the whole body, except for parts of the appendages, and is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligaments. Blubber is more vascularized, or rich in blood vessels, than other adipose tissue.

Blubber can comprise a substantial portion of the body mass of marine mammals. Generally, the blubber layer of the bottlenose dolphin accounts for about 18 to 20 percent of its body weight (SW/BG 2002a; Bryden and Harrison 1986). It may comprise up to fifty percent of the body weight of some marine mammals (Smith 2009) during some points in their lives (Smith 2009).

Blubber can range from a couple of inches thick in dolphins and smaller whales, to up to 4.3 inches (11 centimeters) thick in polar bears (Stirling and Guravich 1988; SW/BG 2002b), to more than a foot thick in some bigger whales, such as right and bowhead whales. However, this thicker layer of blubber is not indicative of larger whales' ability to retain heat better, as the thickness of a whale's blubber does not significantly affect heat loss. More indicative of a whale's ability to retain heat is the water and lipid concentration in blubber, as water reduces heat retaining capacities, and lipid increases them (Kvadsheim et al. 1996).

Function

Blubber serves several different functions. It is the primary location of fat on some mammals, and is essential for storing energy. When food resources are scarce, these layers of blubber with their fat deposits can be used for food and replaced when food is more easily obtained. Blubber is particularly important for species that feed and breed in different parts of the ocean. During these, periods the species are operating on a fat-based metabolism.

Blubber is, however, different from other forms of adipose tissue in its extra thickness, which allows it to serve as an efficient thermal insulator, making blubber essential for thermoregulation, particularly in marine mammals in extreme cold environments. Since heat loss is greater in water than in air, it is vital that warm-blooded animals in cold aquatic environments have a means to retrain heat. Blubber helps to insulate them from the cold. In the bottlenose dolphin, which has a core temperature of about 98.4°F (36.9°C), a heat gradient is seen throughout the blubber to the skin (Ridgway 1972).

Blubber has advantages over fur (as in sea otters) in the respect that although fur can retain heat by holding pockets of air, the air pockets will be expelled under pressure (while diving). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as -40 degrees Fahrenheit. While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator (Galbraith et al. 2001).

Another function of blubber is as an aid in buoyancy, as blubber helps to keep marine mammals buoyant. It also act to streamline the body, because the highly organized, complex collagenous network supports the non-circular cross sections characteristic of cetaceans.

Blubber also may save further energy for marine mammals such as dolphins in that it aids swimming by adding a bounce to the movement. The blubber between the tail flukes and a dolphin's top dorsal fin is crosshatched with elastic fibers that add a spring to the dolphin's strokes. Essentially, the animal is bouncing on a blubber spring, decreasing the amount of energy needed to swim fast (Hirshon and Pabst 2000).

Research into the thermal conductivity of the common bottlenose dolphin's blubber reveals that its thickness varies greatly amongst individuals (Dunkin et al. 2005). However, blubber from emaciated dolphins is much worse of an insulator than that of non-pregnant adults, which in turn have a higher heat conductivity than blubber from pregnant females and pre-adults. Maternal care is extremely important to the survival of offspring that need to develop a thick insulating layer of blubber. The milk from the mammary glands of marine mammals often exceeds forty to fifty percent fat content to support the development of blubber in the young.

Human influences

Uses

Blubber has been used extensively by people for fool and fuel, among other purposes.

Blubber provides a high-energy food. Muktuk, the Inuit/Eskimo word for blubber, formed an important part of the traditional diets of the Inuit and other northernly peoples because of its high energy value (Smith 2009). Seal blubber also has large amounts of vitamin E, selenium, and other antioxidants that hinder oxidation, thus slowing the formation of the free radicals that start a wide variety of diseases. The possible positive effects of consuming blubber may be seen in Greenland; in Uummannaq for example, a hunting district with 3000 residents, no deaths due to cardiovascular diseases occurred in the 1970s. However, emigrants to Denmark have contracted the same diseases as the rest of the population. Mulvad and Pedersen (1992) report that the average 70-year-old Inuit with a traditional diet of whale and seal has arteries as elastic as that of a 20-year-old Danish resident (Mulvad and Pedersen 1992).

One of the major reasons for the whaling trade was the collection of whale blubber. This was rendered down into oil in try pots or later, in vats on factory ships. This rich oil could be then used in the manufacture of soap, leather, and cosmetics (Donovan 2008). Whale oil was also used in candles as wax, and in oil lamps as fuel, and as lubricants for machinery.

Blue whales can yield blubber harvests up to 50 tons.

Toxicity

Studies of blubber in recent years suggest that blubber contains naturally occurring PCB, which are cancer causing and damage the human nervous, immune, and reproductive systems (WHOI 2005). It is not known where the source of this PCB is. Since toothed whales typically place high on the food chain, they are bound to consume large amounts of industrial pollutants. Even baleen whales, by merit of the huge amount of food they consume, are bound to have toxic chemicals stored in their bodies. Recent studies have found high levels of mercury in the blubber of seals of the Canadian Arctic.

References
ISBN links support NWE through referral fees

Whaling

International Whaling Commission · History of whaling · Aboriginal whaling · Dolphin drive hunting
By country
Australia (Western Australia) · Faroe Islands · Iceland · Japan · Norway · Taiwan
Products
Ambergris · Baleen · Blubber · Spermaceti · Whale oil

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.

Retrieved from https://www.newworldencyclopedia.org/p/index.php?title=Blubber&oldid=927169

Content is available under Creative Commons Attribution/Share-Alike License; additional terms may apply. See Terms of Use for details.
Copyright Logo
Powered by MediaWiki