why whales need blubber

From: Pieter Folkens (animalbytes@earthlink.net)
Date: Wed Mar 19 2003 - 12:24:51 EST

  • Next message: Pieter Folkens: "lungs in whales"

    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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