Whales, like all cetaceans, have a thick layer of blubber right beneath their hardy skin. This blubber is vascularised adipose tissue, comprises the hypodermis and covers the entire body with the exception of some of the appendages. Being thicker than most layers of fat differentiates blubber, which is separated from the fibrous tissue that covers the underlying muscles by a loose connective tissue. This enables the blubber to have free movement that is independent of how the muscles below it are moving. The tissues of the blubber do, however, fuse with those of the skin in an almost imperceptible way.
The physical thickness of the blubber varies from one whale species to the next as well as within the body of one animal, since some areas (such as the lower portion of the trunk) require more insulation than others (such as the tip of the head). Generally speaking, the blubber increases in thickness from the front to the back of the whale. However, the proportion of blubber in various areas of a whale’s body remains unchanged, even if the actual quantity increases or decreases. This ensures that the whale remains streamlined and does not acquire a ‘lumpy’ appearance.
The blubber has three primary purposes:
Whales are mammals and are, therefore, endothermic. This is sometimes referred to as being warm-blooded. Therefore, they do not rely solely on the temperature of the waters around them to maintain their own body heat. Still, heat is lost through the skin and needs to be retained as much as possible. The blubber that covers almost their entire bodies is a vital part of maintaining an optimal body temperature, even when the whales swim in the icy depths of some of the world’s coldest oceans.
The blood vessel network of this blubber is the primary means by which the blubber is able to insulate the whale’s body. The blubber is crossed by arterioles (small blood vessels that branch out from an artery and leads to capillaries), which remain very simple in structure and arrangement. Veins (which carry blood away from the tissues and back to the heart to be circulated) completely surround these tiny arterioles. As the blood is carried to and from the blubber, the body is able to retain as much heat as possible.
While it has proved to be a very difficult task to take the normal temperature of a living whale, several attempts have set it at about 95.9 degrees Fahrenheit or 35.5 degrees Celsius. The blubber needs to be thick enough to maintain this, but thin enough to avoid over-heating (since the whale is not able to take shelter under a shady tree when it becomes hot, neither does it sweat). Their high metabolic rate (which enables them to continue swimming without rest) is a major part of maintaining their body temperature.
Blubber conserves the whale’s energy by maintaining a degree of buoyancy, so that it does not have to make continuous effort to avoid sinking to the bottom of the ocean. Blubber is fatty tissue that is less dense than the water around the whale. The proportion of blubber to body size and weight is relatively high to maintain this tissue’s ability to provide such buoyancy. A Blue Whale, for example, has been shown to yield about 50 tons of blubber to whalers that have captured and killed this massive creature.
Whales are in constant movement, and often have to travel extensive distances for the purposes of migration. Cows need to have plenty of reserves in order to nourish and care for their young (particularly during the gestation period). All of these factors indicate that the whale needs a reliable, constant source of energy. The blubber provides just such energy and is always accessible. Blubber is converted to energy, giving the animal sufficient reserves with which to migrate, breed, hunt, maintain body heat and interact with one another, even in the coldest of waters.
Sadly, whales are hunted for their blubber, which is used as food or rendered into oil for wax, cooking oil, and so on.