Blubber

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Blubber is a thick layer of vascularized fat found under the skin of all cetaceans, pinnipeds and sirenians.[1]

Contents

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 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.[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]

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