Blubber
Blubber is a thick layer of vascularized fat found under the skin of all cetaceans, pinnipeds and sirenians.[1]
Description
Lipid-rich, collagen fiber-laced blubber comprises the hypodermis[2] and covers the whole body, except for parts of the appendages, strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligaments. It can comprise up to 50% of the body mass of some marine mammals[1] during some points in their lives and can range from a couple of inches thick in dolphins and smaller whales, to more than a foot thick in some bigger whales, such as Right and Bowhead Whales. However, this is not indictive of larger whales' ability to retain heat better, as the thickness of a whale's blubber does not significantly affect heat loss. More indictive 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.[3]
Function
Blubber serves several different functions. It is the primary location of fat on some mammals, and is essential for storing energy. It is particularly important for species which feed and breed in different parts of the ocean. During these periods the species are operating on a fat-based metabolism. Recent research also shows that blubber may save further energy for marine mammals such as dolphins in that it adds bounce to a dolphin's swim.[4]
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. Blubber is also more vascularized, or rich in blood vessels, than other adipose tissue.
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 °F (4 °C).[5] While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator.[6]
Blubber can also aid in buoyancy, and acts to streamline the body because the highly organized, complex collagenous network supports the non-circular cross sections characteristic of cetaceans.
Research[7] into the thermal conductivity of the common bottlenose dolphin's blubber reveals that its thickness and lipid content vary greatly amongst individuals and across life history categories. 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.
Human Influences
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.[1] Seal blubber has large amounts of Vitamin E, selenium, and other antioxidants that hinder oxidation, which may reduce the effect of the free radicals formed within the body's cells. Damage caused to cells by free radicals are a theorized contributor to some diseases. Whale blubber, which tastes like Arrowroot biscuits, has similar properties.[8]
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. The oil could be then used in the manufacture of soap, leather, and cosmetics.[9] Whale oil was also used in candles as wax, and in oil lamps as fuel.
Blue Whales can yield blubber harvests up to 50 tons.[10]
Toxicity
Recent studies suggest that blubber contains naturally occurring PCB, which are cancer causing and damage the human nervous, immune and reproductive systems.[11][12]. 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 (bioaccumulation). 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.
See also
Works Cited
- ^ a b c "What is Blubber?".
- ^ Struntz DJ et al. "Blubber development in bottlenose dolphins (Tursiops truncatus)." PubMed. From http://www.ncbi.nlm.nih.gov/sites/entrez.
- ^ P. H. Kvadsheim, a, b, , L. P. Folkowb, a and A. S. Blixb, a. "Thermal conductivity of minke whale blubber".
{{cite web}}: CS1 maint: multiple names: authors list (link) - ^ "Science Update--Bouncy Blubber".
- ^ "Secrets of the Ocean Realm".
- ^ Don Galbraith et al. Biology 11. (Canada: McGraw-Hill Ryerson). pg. 12.
- ^ Dunkin, Robin; et al. ""The ontogenetic changes in the thermal properties of blubber from Atlantic bottlenose dolphin Tursiops truncatus"". Journal of Experimental Biology. Retrieved 03-05-2005.
{{cite web}}: Check date values in:|accessdate=(help); Explicit use of et al. in:|author=(help); Italic or bold markup not allowed in:|publisher=(help) - ^ Stefansson, Eero; Adriaensen, Arxontis (1893). Missionärer bland Eskimåer. Uppdrag i Världen (in Swedish). Göteborg: Himmelriket på Jorden Publikationer. p. 138.
{{cite book}}: Unknown parameter|trans_title=ignored (|trans-title=suggested) (help) - ^ Donovan, Greg (2008). "Whaling". Microsoft Encarta.
- ^ "Cetacean". Encyclopædia Britannica. Ultimate Reference Suite. 2008.
- ^ "Chemical Compounds Found In Whale Blubber Are From Natural Sources, Not Industrial Contamination".
- ^ "Japan warned on 'contaminated' blubber". BBC News. 2001-01-24. Retrieved 2009-12-31.