Blubber

Function

Blubber is the primary fat storage layer for some mammals, especially for those that live in water. It is particularly important for species that feed and breed in different parts of the ocean. During these periods, the animals metabolize fat. Blubber may save energy for marine mammals, such as dolphins, in that it adds buoyancy while swimming.

Blubber differs from other forms of adipose tissues due to its extra thickness, which acts as an efficient thermal insulator, making blubber essential for thermoregulation. Blubber is more vascularized—rich in blood vessels—than other adipose tissue.

Blubber has advantages over fur (as in sea otters) in that, though fur retains heat by holding pockets of air, the air expels under pressure (i.e., when the animal dives). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as 4 °C (40 °F). While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator.

Blubber adds buoyancy and streamlines the body, because the organized, complex collagenous network supports the noncircular cross sections characteristic of cetaceans. The buoyancy of blubber could be problematic for bottom-feeding marine mammals such as sirenians and the extinct marine sloths, both of which do or probably did have limited amounts of it for that reason.

Research on 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. Blubber from emaciated dolphins is a poorer insulator than that from nonpregnant adults, which in turn has a higher heat conductivity than blubber from pregnant females and adolescents.

Human influences

Uses

Uqhuq, or uqsuq, ("blubber" in the Inuktitut language) is an important part of the traditional diets of the Inuit and of other northern peoples, because of its high energy value and availability.

Whaling largely targeted the collection of blubber: whalers rendered it into oil in try pots, or later, in vats on factory ships. The oil could serve in the manufacture of soap, leather, and cosmetics. Whale oil was used in candles as wax, and in oil lamps as fuel. A single blue whale can yield a blubber harvest of up to 50 tons.

Health

Blubber from whales and seals contains omega-3 fatty acids and vitamin D. Without the vitamin D, for example, the Inuit and other natives of the Arctic would likely suffer from rickets. There is evidence that blubber and other fats in the arctic diet also provide the calories needed to replace the lack of carbohydrates, which are found in the diets of cultures in the rest of the world.

Toxicity

In the 21st century, blubber contains man-made polychlorinated biphenyl (PCBs), carcinogens that damage human nervous, immune, and reproductive systems. The source of PCB concentrations is unknown. Since toothed whales are high on the food chain, they likely 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. Additionally, there are high levels of mercury in the blubber of seals of the Canadian arctic.