A key feature of mammals is the ability to thermoregulate (maintain a
constant body temperature). For most mammals hair and perspiration do
the trick. For human (hairless apes), clothing and controlled
environments (air conditioning) are technological substitutes. Loss of
heat kills (hypothermia).
In water, body heat is lost through conduction. Warmth is conducted
directly from the skin to the water. To control this heat loss whales
adapted a subcutaneous (below the outer layer of skin) tissue called
blubber which serves two purposes: 1) a suitable insulation from the
cold (since they have insufficient hair and no clothes to do the job),
and 2) energy storage. It also helps the body fill out a streamline
form without bony bumps and protrusions which would add drag to a
swimming whale.
Way back when the terrestrial ancestors of whales first experimented
with the idea of foraging in the water, the world was much warmer. They
lived next to a broad tropical sea with a nominal temperature close
enough to their body temperature that heat loss by conduction was not a
big deal. With this convenience, whale ancestors evolved the basic
structures of an aquatic lifestlye. That was 55 to 40 million years
ago. At about 40 to 37 million years ago, the southern continents
separated from Antarctica creating a circumpolar current and an oceanic
feature called the Antarctic Convergence. All this and more cooled the
world's oceans requiring the early whales to adapt or die. One of the
adaptations was a significant insulating layer about the body: blubber.
Cheers,
Pieter Folkens
Alaska Whale Foundation
On Wednesday, March 19, 2003, at 12:00 AM, Urie Salant wrote:
> why do whales need blubber?
> yu13354@hotmail.co.il
> thanks
>
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