_Heat Conservation_
As whales extended their operations into the icy waters of polar regions
or into the cold waters of the ocean depths, they had to develop means
of keeping warm. Anyone who has attempted to swim in cold water knows
how quickly one loses his body heat and becomes chilled. Whales minimize
the heat loss by accumulating a thick layer of fat just below the
surface of the skin. The fatty layer, called blubber, not only keeps the
whale warm, but it also provides for food storage. It has already been
stressed how important it is for whales to survive long periods without
eating, so it is likely that the two specializations arose together.
There are, however, extensive areas of the whale which cannot be
blanketed with fat and these are the flippers and the large tail flukes.
It has been observed that the blood going into these structures gives up
its heat not to the outside but to the veins which parallel and surround
the arteries. By this anatomical feature most of the heat which would
otherwise be lost to the water, is recaptured by the veins which deliver
the heat back into the body. Of course, this means that the tissues of
the tail flukes and flippers function at temperatures much lower than
those found within the body. Here we find that nature was using the
principal of the heat exchanger long before man discovered it or put it
to work in air conditioning.
Whales are so well insulated that they stay quite warm 24-36 hours after
death. Whalers must process the whales quickly, for otherwise, at the
elevated body temperature, decomposition proceeds most rapidly and ruins
much of the meat. It is possible that the baleen-bearing whales do not
cross the warm equatorial waters because they overheat. No one has yet
determined whether the newborn young have a sufficient layer of fat to
protect them from the cold water, and it has been suggested that whales
calve in temperate waters to prevent the babies from being chilled.
However, there are species like the narwhal and the white whale which
calve in Arctic waters.
_Buoyancy_
Another aspect to the extensive deposits of fat is that these tissues
are lighter than water and help counteract the heaviness of the whale's
body so that with the assistance of the lungs neutral buoyancy is
achieved. The fat is accumulated in between the muscle strands, and in
fact, in every available nook and cranny.
_Food Storage_
Much of this fat is drawn upon for food. Whenever a whale is existing on
its fatty tissue, acetone is one of the waste products which must be
eliminated in the breath. This pungent material makes the breath very
strong and noticeable at these times. Certainly among whales, there is
no stigma attached to being fat or having halitosis.
Ordinarily fatty tissues only accumulate when there is a surplus of food
over the needs of the animal. You might suspect that whales would need
to stockpile fat first, in order to remain warm and buoyant, and that
growth would be curtailed and accomplished last. However, studies on the
growth of whales show that the efficiency of food gathering is so high
and food so plentiful, that growth not only continues but at a
tremendous pace.